The peak shaving dispatch options attempt to discharge the battery during times of peak demand over a forecast period. Peak shaving dispatch considers the load, and either the available solar resource for PV systems, or the AC output for generic battery systems over the forecast period and calculates a grid power target for each time step in that period. It then charges or discharges the battery as possible given the battery's capacity and state of charge to meet the target. Use this option to reduce monthly demand charges when the rates on the Electricity Rates page include demand rates.
+
The peak shaving dispatch options attempt to discharge the battery during times of peak demand over a forecast period. Peak shaving dispatch considers the load, and either the available solar resource for PV systems, or the AC output for other systems over the forecast period and calculates a grid power target for each time step in that period. It then charges or discharges the battery as possible given the battery's capacity and state of charge to meet the target. Use this option to reduce monthly demand charges when the rates on the Electricity Rates page include demand rates.
Peak shaving discharges the battery each day to reduce that day's peak load. This results in more battery cycling than would result from a dispatch strategy that discharges the battery once a month to reduce the peak load.
For a detailed description of the behind-the-meter peak shaving dispatch algorithm, see DiOrio, N. (2017). An Overview of the Automated Dispatch Controller Algorithms in SAM. NREL/TP-6A20-68614. (PDF 770 KB)
Automated dispatch dispatches the battery in response to changes in the power price to maximize revenue from power sales. Use this option for PPA projects that involve time-of-delivery price multipliers or Merchant Plant projects.
PV smoothing
-
PV smoothing dispatches the battery for photovoltaic-battery systems to limit power ramp rates at the grid interconnection point. Use this option for projects required to meet ramp rate limits. This option is available for PV battery and Generic battery systems. It is not available for standalone batteries.
+
PV smoothing dispatches the battery for photovoltaic-battery systems to limit power ramp rates at the grid interconnection point. Use this option for projects required to meet ramp rate limits. This option is available for PV battery and Custom Generation Profile - Battery systems. It is not available for standalone batteries.
Dispatch to custom time series
Dispatch the battery according to time series charge and discharge power values you provide. Use this option when you know exactly how you want the battery to charge and discharge.
Manual dispatch
@@ -552,8 +552,8 @@
Charge Options
SAM's front-of-meter automated dispatch algorithm attempts to charge and discharge the battery to maximize revenue from power sales to the grid. It calculates a battery power target for each time step, and charges or discharges the battery to attempt to meet the target, given any constraints on battery capacity and battery state of charge, and accounting for power conversion losses. Note that in some time steps, depending on the battery's state of charge and other constraints, the battery discharge power may be less than the target.
-
You can explore the results of the automated dispatch by comparing the output variables Electricity battery power target for automated dispatch to Electricity to/from battery. Other useful output variables include Market sell rate (year 1) representing the power prices used for battery dispatch calculations, Battery state of charge, Electricity to grid from battery,and Electricity to grid from system (for PV Battery and Generic Battery configurations).
-
Automated battery dispatch responds to power prices that vary over time, which can be defined as a PPA price with time-of-delivery multipliers for PPA projects, or market prices for Merchant Plant projects. For batteries connected to a power system (PV Battery and Generic Battery configurations), battery dispatch also responds to the availability of power from the system. Battery dispatch also accounts for the cost of cycling the battery based on a prediction of how battery cycling will affect battery degradation and replacements.
+
You can explore the results of the automated dispatch by comparing the output variables Electricity battery power target for automated dispatch to Electricity to/from battery. Other useful output variables include Market sell rate (year 1) representing the power prices used for battery dispatch calculations, Battery state of charge, Electricity to grid from battery,and Electricity to grid from system (for PV Battery and Custom Generation Profile - Battery configurations).
+
Automated battery dispatch responds to power prices that vary over time, which can be defined as a PPA price with time-of-delivery multipliers for PPA projects, or market prices for Merchant Plant projects. For batteries connected to a power system (PV Battery and Custom Generation Profile - Battery configurations), battery dispatch also responds to the availability of power from the system. Battery dispatch also accounts for the cost of cycling the battery based on a prediction of how battery cycling will affect battery degradation and replacements.
The automated dispatch options determine the time horizon over which the algorithm maximizes revenue
Similar to the look ahead automated dispatch option, except use different time series data for the forecast of power available to charge the battery than that used to model the system's power output:
•For the PV Battery configuration, use a different weather file than the one on the Location and Resource page.
-
•For the Generic Battery configuration, use a different generation profile for the forecast than the generation profile on the Power Plant page.
+
•For the Custom Generation Profile - Battery configuration, use a different generation profile for the forecast than the generation profile on the Power Plant page.
Note. The custom forecast option is not available for standalone batteries, which do not dispatch in response to a generation profile of a photovoltaic array or other power generating equipment.
Frequency to update dispatch
For any of the three automated dispatch options, determines how often a new dispatch decision is made.
@@ -581,7 +581,7 @@
Charge Options
Weather file for automated dispatch
For the PV Battery configuration, the weather file to use for the custom forecast option. Click Browse to choose a weather file in the SAM CSV format.
Generation profile for automated dispatch
-
For the Generic Battery configuration, a time series generation profile (hourly or subhourly) to use for the custom forecast option. Click Edit array to import or paste a generation profile.
+
For the Custom Generation Profile - Battery configuration, a time series generation profile (hourly or subhourly) to use for the custom forecast option. Click Edit array to import or paste a generation profile.
Cycle Degradation Penalty
The cycle degradation penalty represents the future cost of replacing the battery. It allows SAM to account for the battery replacement cost in the battery dispatch decision. For any of the automated dispatch options, choose a method for estimating the cost of cycling the battery:
•Calculate automatically if you want SAM to calculate the cost.
Note. The dispatch schedule REopt calculates is based on a different representation of the photovoltaic-battery system and weather file than SAM uses for simulations.
This option has the following requirements:
•Battery bank sizing is in the Set Desired Bank Size mode.
-
•The performance model is either PV - Battery or PVWatts - Battery. Optimal sizing and dispatch is not available for the Generic - Battery, hybrid systems, or other models with storage.
+
•The performance model is either PV - Battery or PVWatts - Battery. Optimal sizing and dispatch is not available for the Custom Generation Profile - Battery, hybrid systems, or other models with storage.
•Hourly simulation time step, which is determined by the weather file time step. The sizing and dispatch does not work with subhourly simulations.
•For the Detailed PV model, the sizing and optimization does not work if more than one subarray is enabled.
For information about REopt, see:
@@ -813,7 +813,7 @@
For photovoltaic-battery systems, SAM can model a battery that is connected to either the DC or AC side of the photovoltaic inverter.
Notes.
-The DC connected option is only available with the PV Battery configuration. The Standalone and Generic Battery configurations assume that the battery is the only DC component in the system.
+The DC connected option is only available with the PV Battery configuration. The Standalone and Custom Generation Profile - Battery configurations assume that the battery is the only DC component in the system. The Power Converters conversion efficiency inputs account for electrical losses associated with any battery power converter equipment except for the photovoltaic inverter. SAM models each battery converter as a fixed conversion efficiency.
@@ -889,6 +889,20 @@
Time series losses
Choose this option to specify hourly or subhourly time series losses.
Time series losses
Click Edit array to enter or import kW loss values for each time step of the simulation.
+
Battery Availability
+
Battery availability losses can represent battery downtime for maintenance, system outages, or other times when the battery can neither charge nor discharge. The battery availability loss has the effect of reducing electricity to/from battery and battery state of charge in the time steps with availability losses.
+
To explore the effect of battery availability losses, use the following output variables
+
•Electricity to/from battery AC (kW)
+
•Battery state of charge (%)
+
•Battery availability loss (%)
+
The Electricity to [...] from battery (kW) and Electricity to battery from [...] (kW) variables may also be useful.
+
Battery availability losses affect both power and capacity. For a time step with availability loss, the loss percentage for that time step applies to both the battery power (kW) and capacity (kWh). Because the availability loss is intended to represent downtime for maintenance, the loss percentage also applies to the battery state of charge, assuming that cells are discharged to safely perform maintenance. This means that the battery will have a lower state of charge at the end of the availability loss period than at the beginning.
+
Note. If the battery state of charge (SOC) is low when the availability loss period begins, the SOC could fall below the minimum SOC from the Battery Dispatch page. For example, a battery with a 10% minimum SOC that is at its minimum charge state when a period of 50% availability begins, would have a SOC of 5% at the end of the period.
+
Edit losses
+
The Edit Losses window allows you to define loss factors as follows:
+
•Constant loss is a single loss factor that applies to the system's entire output. You can use this to model an availability factor.
+
•Time series losses apply to specific time steps.
+
SAM multiplies the battery power in each time step by the loss percentage that you specify for that time step. For a given time step, a loss of zero would result in no adjustment. A loss of 5% would reduce the power by 5%, and a loss of -5% would increase the power by 5%.
Battery Thermal
The battery thermal model calculates the battery temperature in each simulation time step. Battery temperature affects battery capacity and degradation. The model's two main heat-transfer terms are transfer between the battery and its environment, and energy generated by resistive heating inside the battery. The cell internal resistance input is under Battery Voltage.
Note. To verify that the battery thermal model is working as you expect, look at the Battery temperature output variable in the time series results to make sure it is within a reasonable range. If the temperature is higher or lower than you expect, you may need to adjust the thermal or physical properties inputs.
For photovoltaic-battery systems, SAM can model a battery that is connected to either the DC or AC side of the photovoltaic inverter.
Notes.
-The DC connected option is only available with the PV Battery configuration. The Standalone and Generic Battery configurations assume that the battery is the only DC component in the system.
+The DC connected option is only available with the PV Battery configuration. The Standalone and Custom Generation Profile - Battery configurations assume that the battery is the only DC component in the system. The Power Converters conversion efficiency inputs account for electrical losses associated with any battery power converter equipment except for the photovoltaic inverter. SAM models each battery converter as a fixed conversion efficiency.
@@ -869,6 +869,20 @@
Time series losses
Choose this option to specify hourly or subhourly time series losses.
Time series losses
Click Edit array to enter or import kW loss values for each time step of the simulation.
+
Battery Availability
+
Battery availability losses can represent battery downtime for maintenance, system outages, or other times when the battery can neither charge nor discharge. The battery availability loss has the effect of reducing electricity to/from battery and battery state of charge in the time steps with availability losses.
+
To explore the effect of battery availability losses, use the following output variables
+
•Electricity to/from battery AC (kW)
+
•Battery state of charge (%)
+
•Battery availability loss (%)
+
The Electricity to [...] from battery (kW) and Electricity to battery from [...] (kW) variables may also be useful.
+
Battery availability losses affect both power and capacity. For a time step with availability loss, the loss percentage for that time step applies to both the battery power (kW) and capacity (kWh). Because the availability loss is intended to represent downtime for maintenance, the loss percentage also applies to the battery state of charge, assuming that cells are discharged to safely perform maintenance. This means that the battery will have a lower state of charge at the end of the availability loss period than at the beginning.
+
Note. If the battery state of charge (SOC) is low when the availability loss period begins, the SOC could fall below the minimum SOC from the Battery Dispatch page. For example, a battery with a 10% minimum SOC that is at its minimum charge state when a period of 50% availability begins, would have a SOC of 5% at the end of the period.
+
Edit losses
+
The Edit Losses window allows you to define loss factors as follows:
+
•Constant loss is a single loss factor that applies to the system's entire output. You can use this to model an availability factor.
+
•Time series losses apply to specific time steps.
+
SAM multiplies the battery power in each time step by the loss percentage that you specify for that time step. For a given time step, a loss of zero would result in no adjustment. A loss of 5% would reduce the power by 5%, and a loss of -5% would increase the power by 5%.
Battery Thermal
The battery thermal model calculates the battery temperature in each simulation time step. Battery temperature affects battery capacity and degradation. The model's two main heat-transfer terms are transfer between the battery and its environment, and energy generated by resistive heating inside the battery. The cell internal resistance input is under Battery Voltage.
Note. To verify that the battery thermal model is working as you expect, look at the Battery temperature output variable in the time series results to make sure it is within a reasonable range. If the temperature is higher or lower than you expect, you may need to adjust the thermal or physical properties inputs.
To model curtailment, or forced outages or reduction in power output required by the grid operator, use the inputs on the Grid Limits page. The Grid Limits page is not available for all performance models.
-For the PV Battery model, battery dispatch is affected by the system availability losses. For the PVWatts Battery, Generic Battery, and Standalone Battery battery dispatch ignores the system availability losses.
+For the PV Battery model, battery dispatch is affected by the system availability losses. For the PVWatts Battery, Custom Generation Profile - Battery, and Standalone Battery battery dispatch ignores the system availability losses.
To edit the system availability losses, click Edit losses.
The Edit Losses window allows you to define loss factors as follows:
•Constant loss is a single loss factor that applies to the system's entire output. You can use this to model an availability factor.
A cost per kW of gross nameplate capacity to account for plant-related costs not associated with specific components of the plant.
Contingency
A percentage of the sum of the above costs to account for expected uncertainties in direct cost estimates.
-
Total Direct Capital Cost ($)
+
Total Direct Capital Cost, $
The sum of the direct capital costs, including contingency costs.
Indirect Capital Costs
An indirect cost is typically one that cannot be identified with a specific piece of equipment or installation service.
-
Engineer, Procure, Construct (% and $)
+
Engineer Procure Construct, % and $
Engineer-Procure-Construct costs, sometimes abbreviated as EPC costs, are costs associated with the design and construction of the project, which SAM calculates as the sum of a “non-fixed cost” and with a fixed cost.
-
Project, Land, Miscellaneous (% and $)
+
Project Land Miscellaneous, % and $
Project-Land-Miscellaneous costs are those associated with the purchase and preparation of land, and other indirect costs not included in the EPC category.
% of Direct Cost
A value that you type as a percentage of Total Direct Capital Cost (under Direct Capital Costs)
@@ -556,9 +556,9 @@
A value that you type as a fixed amount in dollars.
Total
A value that SAM calculates as the sum of Non-fixed Cost and Fixed Cost.
-
Total Indirect Cost ($)
+
Total Indirect Cost, $
The sum of engineer-procure-construct costs, project-land-miscellaneous costs.
-
Sales Tax (%)
+
Sales Tax
Sales tax basis, %
The percentage of total direct cost used to the calculate sales tax amount.
SAM calculates the total sales tax amount by multiplying the sales tax rate from the Financial Parameters page by the sales tax basis on the Installation Costs page:
A direct capital cost represents an expense for a specific piece of equipment or installation service that applies in year zero of the cash flow.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different direct capital cost categories does not affect the final results.
-
Plant Cost ($)
+
Plant Cost, $
A fixed dollar amount.
-
Plant cost per capacity ($/W)
+
Plant cost per capacity, $/W
A cost per Watt of nameplate capacity from the Power Plant page.
If the system includes a battery, you can specify the battery installation cost in $/kWh of battery capacity, $/kW of maximum discharge power, or both:
-
Battery cost per capacity ($/kWh DC)
+
Battery cost per capacity, $/kWh DC
Battery installation cost in $/kWh of nominal bank capacity from the Battery Cell and System page.
-
Battery cost per kW ($/kW DC)
+
Battery cost per kW, $/kW DC
Battery installation cost in $/kW of maximum charge power from the Battery Cell and System page.
-
Contingency cost (%)
+
Contingency cost, %
A percentage of the sum of the plant and battery costs to account for expected uncertainties in direct capital cost estimates.
-
Total Direct Cost ($)
+
Total Direct Cost, $
The sum of plant cost, plant cost per capacity, and contingency costs.
Indirect Capital Costs
An indirect cost is typically one that cannot be identified with a specific piece of equipment or installation service.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different indirect capital cost categories does not affect the final results.
-
Engineering and other EPC costs (% and $)
+
Engineering and other EPC costs, % and $
Costs associated with the design and construction of the project.
% of Direct Cost is a value that you type as a percentage of Total direct cost (under Direct Capital Cost). SAM displays the equivalent dollar amount.
$ is a value that you type as an amount in dollars.
-
Permitting and other EPC costs (% and $)
+
Permitting and other EPC costs, % and $
Costs associated with land purchases, permitting, and other costs.
% of Direct Cost is a value that you type as a percentage of Total direct cost (under Direct Capital Cost). SAM displays the equivalent dollar amount.
$ is a value that you type as a fixed amount in dollars.
-
Total Indirect Cost ( $)
+
Total Indirect Cost, $
The sum of indirect capital costs.
-
Sales Tax (%)
+
Sales Tax
Sales tax basis, %
The percentage of total direct cost used to the calculate sales tax amount.
SAM calculates the total sales tax amount by multiplying the sales tax rate from the Financial Parameters page by the sales tax basis on the Installation Costs page:
A direct capital cost represents an expense for a specific piece of equipment or installation service that applies in year zero of the cash flow.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different direct capital cost categories does not affect the final results.
-
Heater cost ($/kWt)
+
Heater cost, $/kWt
A cost per kW of heater thermal power for expenses related to the electric heater equipment, including equipment and labor.
-
Thermal energy storage cost ($/kWht)
+
Thermal energy storage cost, $/kWht
Cost per thermal megawatt-hour of storage capacity to account for expenses related to installation of the thermal storage system, including equipment and labor.
-
Balance of plant cost ($/kWe)
+
Balance of plant cost, $/kWe
Cost per electric kilowatt of power cycle gross capacity to account for additional costs.
-
Power cycle cost ($/kWe)
+
Power cycle cost, $/kWe
Cost per electric kilowatt of power cycle gross capacity to account for the installation of the power cycle, including equipment and labor.
-
Contingency (%)
+
Contingency, %
A percentage of the sum of the heater, thermal energy storage, and power cycle costs to account for expected uncertainties in direct cost estimates.
-
Total Direct Cost ($)
+
Total Direct Cost, $
The sum of heater, thermal energy storage, and power cycle, and contingency costs.
Indirect Capital Costs
An indirect cost is typically one that cannot be identified with a specific piece of equipment or installation service.
@@ -556,7 +556,7 @@
A cost in dollars per AC Watt of nameplate capacity.
$
A fixed dollar amount
-
Total Indirect Cost ($)
+
Total Indirect Cost, $
The sum of engineer-procure-construct costs, project-land-miscellaneous costs, and sales tax.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different direct capital cost categories does not affect the final results.
A direct capital cost represents an expense for a specific piece of equipment or installation service that applies in year zero of the cash flow.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different direct capital cost categories does not affect the final results.
-
Module ($/Wdc or $/Unit)
+
Module, $/Wdc or $/Unit
You can specify the module cost either in $/Wdc or $/unit:
•Dollars per watt multiplied by System nameplate capacity from the PV System page, or
•Dollars per unit, where the number of modules is assumed to be one.
-
Inverter ($/Wac or $/Unit)
+
Inverter, $/Wac or $/Unit
For PVWatts, the inverter cost is either dollars per watt AC or DC, or dollars per inverter:
•Dollars per watt DC multiplied by the system nameplate capacity from the PV System page, or
•Dollars per watt AC multiplied by the system nameplate capacity and divided by the DC to AC Derate Factor on the System Design page, or
@@ -550,9 +550,9 @@
A cost proportional to the battery's nominal power rating, equal to the Maximum charge power (AC) on the Battery Storage page.
Fuel Cell $/kW
A cost proportional to the fuel cell stack nameplate capacity, equal to the Cell stack nameplate on the Fuel Cell page.
-
Contingency (%)
+
Contingency, %
A percentage of the sum of the module, inverter, balance-of-system, installation labor, and installer margin and overhead costs that you can use to account for expected uncertainties in direct cost estimates.
-
Total Direct Cost ($)
+
Total Direct Cost, $
The sum of module, inverter, balance-of-system, installation labor, installer margin and overhead costs, and contingency costs.
Indirect Capital Costs
An indirect cost is typically one that cannot be identified with a specific piece of equipment or installation service.
@@ -571,7 +571,7 @@
Land Costs
SAM calculates the total land cost as the sum of Land area, Land purchase, and Land prep. and transmission. The land cost categories use the Cost $/acre category in addition to the categories for the other indirect costs.
Note. The land area input is independent of the PV array size or other input parameters. If you want to include land area costs in your analysis, be sure to specify a land area in acres that is appropriate for your system's design.
-
Sales Tax (%)
+
Sales Tax
Sales tax basis, %
The percentage of total direct cost used to the calculate sales tax amount.
SAM calculates the total sales tax amount by multiplying the sales tax rate from the Financial Parameters page by the sales tax basis on the Installation Costs page:
A direct capital cost represents an expense for a specific piece of equipment or installation service that applies in year zero of the cash flow.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different direct capital cost categories does not affect the final results.
-
Site Improvements ($/m2)
+
Site Improvements, $/m2
A cost per square meter of solar field area to account for expenses related to site preparation and other equipment not included in the solar field cost category.
-
Solar Field ($/m2)
+
Solar Field, $/m2
A cost per square meter of solar field area to account for expenses related to installation of the solar field, including labor and equipment.
-
Storage ($/kWht)
+
Storage, $/kWht
Cost per thermal megawatt-hour of storage capacity to account for expenses related to installation of the thermal storage system, including equipment and labor.
-
Fossil Backup ($/kWe)
+
Fossil Backup, $/kWe
Cost per electric megawatt of power block gross capacity to account for the installation of a fossil backup system, including equipment and labor.
-
Power Plant ($/kWe)
+
Power Plant, $/kWe
Cost per electric megawatt of power block gross capacity to account for the installation of the power block, including equipment and labor.
-
Balance of Plant ($/kWe)
+
Balance of Plant, $/kWe
Cost per electric megawatt of power block gross capacity to account for additional costs.
-
Contingency (%)
+
Contingency, %
A percentage of the sum of the site improvements, solar field, HTF system, storage, fossil backup, and power plant costs to account for expected uncertainties in direct cost estimates.
-
Total Direct Cost ($)
+
Total Direct Cost, $
The sum of improvements, solar field, HTF system, storage, fossil backup, power plant costs, and contingency costs.
Indirect Capital Costs
An indirect cost is typically one that cannot be identified with a specific piece of equipment or installation service.
A direct capital cost represents an expense for a specific piece of equipment or installation service that applies in year zero of the cash flow.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different direct capital cost categories does not affect the final results.
-
Site Improvements ($/m2)
+
Site Improvements,$/m2
A cost per square meter of solar field area to account for expenses related to site preparation and other equipment not included in the solar field cost category.
-
Solar Field ($/m2)
+
Solar Field,$/m2
A cost per square meter of solar field area to account for expenses related to installation of the solar field, including labor and equipment.
-
HTF System ($/m2)
+
HTF System, $/m2
A cost per square meter of solar field area to account for expenses related to installation of the heat transfer fluid pumps and piping, including labor and equipment.
-
Fossil Backup ($/kWe)
-
Cost per electric megawatt of power block gross capacity to account for the installation of a fossil backup system, including equipment and labor.
-
Power Plant ($/kWe)
-
Cost per electric megawatt of power block gross capacity to account for the installation of the power block, including equipment and labor.
-
Balance of Plant ($/kWe)
-
Cost per electric megawatt of power block gross capacity to account for additional costs.
-
Contingency (%)
+
Fossil Backup, $/kWe
+
For CSP systems only. Cost per electric megawatt of power block gross capacity to account for the installation of a fossil backup system, including equipment and labor.
+
Power Plant, $/kWe
+
For CSP systems only. Cost per electric megawatt of power block gross capacity to account for the installation of the power block, including equipment and labor.
+
Heat Sink, $/kWht
+
For IPH systems only. Cost per thermal kilowatt-hour of heat sink capacity for expenses related to installation of the heat sink, including labor and equipment.
+
Balance of Plant, $/kWe for CSP, $/kWt for IPH
+
Cost per electric or thermal kilowatt of power block gross capacity to account for additional costs.
+
Contingency, %
A percentage of the sum of the site improvements, solar field, HTF system, storage, fossil backup, and power plant costs to account for expected uncertainties in direct cost estimates.
-
Total Direct Cost ($)
+
Total Direct Cost, $
The sum of improvements, solar field, HTF system, storage, fossil backup, power plant costs, and contingency costs.
Indirect Capital Costs
An indirect cost is typically one that cannot be identified with a specific piece of equipment or installation service.
A direct capital cost represents an expense for a specific piece of equipment or installation service that applies in year zero of the cash flow.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different direct capital cost categories does not affect the final results.
-
Heater cost ($/kWt)
+
Heater cost, $/kWt
A cost per kW of heater thermal power for expenses related to the electric heater equipment, including equipment and labor.
-
Thermal energy storage cost ($/kWht)
+
Thermal energy storage cost, $/kWht
Cost per thermal megawatt-hour of storage capacity to account for expenses related to installation of the thermal storage system, including equipment and labor.
-
Balance of plant cost ($/kWe)
+
Balance of plant cost, $/kWe
Cost per electric kilowatt of power cycle gross capacity to account for additional costs.
-
Power cycle cost ($/kWe)
+
Power cycle cost, $/kWe
Cost per electric kilowatt of power cycle gross capacity to account for the installation of the power cycle, including equipment and labor.
-
Contingency (%)
+
Contingency, %
A percentage of the sum of the heater, thermal energy storage, and power cycle costs to account for expected uncertainties in direct cost estimates.
-
Total Direct Cost ($)
+
Total Direct Cost, $
The sum of heater, thermal energy storage, and power cycle, and contingency costs.
Indirect Capital Costs
An indirect cost is typically one that cannot be identified with a specific piece of equipment or installation service.
A direct capital cost represents an expense for a specific piece of equipment or installation service that applies in year zero of the cash flow.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different direct capital cost categories does not affect the final results.
-
Module Cost ($/Wdc or $/Unit)
+
Module Cost, $/Wdc or $/Unit
For the detailed photovoltaic model, the module cost is expressed per unit or per DC Watt:
•Dollars per DC watt multiplied by Nameplate Capacity (at reference conditions) on the System Design page, or
•Dollars per unit multiplied by Total Modules on the System Design page.
For PVWatts, the module cost is expressed per unit or per DC Watt:
•Dollars per watt multiplied by Nameplate Capacity on the PVWatts System Design page, or
•Dollars per unit, where the number of modules is assumed to be one.
-
Inverter ($/Wac or $/Unit)
+
Inverter, $/Wac or $/Unit
For the detailed photovoltaic model, the cost of inverters in the system is expressed in dollars per AC Watt or dollars per inverter:
•Dollars per AC watt multiplied by Total Inverter Capacity on the System Design page, or
•Dollars per unit multiplied by Number of Inverters in the Actual Layout column on the System Design page.
For PVWatts, the inverter cost is either dollars per watt or dollars per inverter:
•Dollars per watt multiplied by the product of DC Rating and DC to AC Derate Factor on the System Design page, or
•Dollars per unit where the number of inverters is assumed to be one.
-
Battery ($/kWh, $/kW)
+
Battery, $/kWh and $/kW
For systems with batteries, the battery installation cost is expressed in $/kWh of total battery capacity, $/kW of maximum charge/discharge power, or both. Specify the battery replacement cost separately using the $/kWh cost on the Operating Costs page.
PV Battery:
•Dollars per kilowatt-hour multiplied by Nominal bank capacity on the Battery Cell and System page.
A direct capital cost represents an expense for a specific piece of equipment or installation service that applies in year zero of the cash flow.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different direct capital cost categories does not affect the final results.
-
Collector cost ($/m2, $/Unit, or $/W)
+
Collector cost, $/m2 or $/Unit or $/W
The cost of collectors in the system. You can either include labor costs for collector installation in the collector cost, or account for it separately using the installation cost category. The total collector cost is calculated as either:
•Dollars per square meter multiplied by collector area on the SWH System page, or
•Dollars per unit, representing the total collector cost, or
•Dollars per thermal watt of collector capacity multiplied by the nameplate capacity on the SWH System page.
-
Storage cost ($/m3 or $/Unit)
+
Storage cost, $/m3 or $/Unit
The cost of the solar storage tanks. The total storage cost is either:
•Dollars per cubic meters multiplied by the storage volume on the SWH System page, or
•Dollars per unit, representing the total storage cost.
-
Balance of system ($)
+
Balance of system, $
A fixed cost that can be used to account for costs not included in the collector and storage cost categories, for example, the mounting racks and piping.
-
Installation cost ($)
+
Installation cost, $
A fixed cost that can be used to account for labor or other costs not included in the other cost categories.
-
Contingency (%)
+
Contingency, %
A percentage of the sum of the collector, storage, balance-of-system, and installation costs to account for expected uncertainties in direct cost estimates.
-
Total direct cost ($)
+
Total direct cost, $
The sum of collector, storage, balance-of-system, installation, and contingency costs.
Indirect Capital Costs
An indirect cost is typically one that cannot be identified with a specific piece of equipment or installation service.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different indirect capital cost categories does not affect the final results.
-
Engineer, Procure, Construct (% and $)
+
Engineer Procure Construct, % and $
Engineer-procure-construct costs, sometimes abbreviated as EPC costs, are costs associated with the design and construction of the project, which SAM calculates as the sum of a "non-fixed cost" and a fixed cost.
-
% of Direct Cost is a value that you type as a percentage of Total Direct Cost (under Direct Capital Cost).
+
% of Direct Cost is a value that you type as a percentage of Total Direct Cost under Direct Capital Cost).
Non-fixed Cost is the product of % of Direct Cost and Total Direct Cost.
Fixed Cost is a value that you type as a fixed amount in dollars.
The total engineer-procure-construct cost is the sum of Non-fixed Cost and Fixed Cost.
-
Project, Land, Maintenance (% and $)
+
Project Land Maintenance, % and $
Costs associated with land purchases, permitting, and other costs which SAM calculates as the sum of a "non-fixed cost" and a fixed cost.
SAM does not use the land area value shown on the solar field page for trough and tower systems in the land cost calculation.
% of Direct Cost is a value that you type as a percentage of Total Direct Cost (under Direct Capital Cost).
Non-fixed Cost is the product of % of Direct Cost and Total Direct Cost.
Fixed Cost is a value that you type as a fixed amount in dollars.
The total project-land-miscellaneous cost is the sum of Non-fixed Cost and Fixed Cost.
-
Total indirect cost ( $)
+
Total indirect cost, $
The sum of engineer-procure-construct costs, project-land-miscellaneous costs.
-
Sales tax (%)
+
Sales tax
Sales tax of, %
The sales tax rate from the Financial Parameters page.
A direct capital cost represents an expense for a specific piece of equipment or installation service that applies in year zero of the cash flow.
Note: Because SAM uses only the total installed cost value in cash flow calculations, how you distribute costs among the different direct capital cost categories does not affect the final results.
-
Site Improvements ($/m2)
+
Site Improvements, $/m2
A cost per square meter of solar field area to account for expenses related to site preparation and other equipment not included in the solar field cost category.
-
Solar Field ($/m2)
+
Solar Field, $/m2
A cost per square meter of solar field area to account for expenses related to installation of the solar field, including labor and equipment.
-
HTF System ($/m2)
+
HTF System, $/m2
A cost per square meter of solar field area to account for expenses related to installation of the heat transfer fluid pumps and piping, including labor and equipment.
-
Storage ($/kWht)
+
Storage, $/kWht
Cost per thermal megawatt-hour of storage capacity to account for expenses related to installation of the thermal storage system, including equipment and labor.
-
Fossil Backup ($/kWe)
-
Cost per electric megawatt of power block gross capacity to account for the installation of a fossil backup system, including equipment and labor.
+
Fossil Backup, $/kWe
+
For CSP Systems only. Cost per electric megawatt of power block gross capacity to account for the installation of a fossil backup system, including equipment and labor.
Note.In versions of SAM released after February 2020, fossil backup is not available for the Physical Trough model because it was not incorporated into the new dispatch controller logic at the time of the software release, so the Fossil Backup cost should be zero. If you want to use fossil backup, use version SAM 2018.11.11, available on the SAM website Download page.
-
Power Plant ($/kWe)
-
Cost per electric megawatt of power block gross capacity to account for the installation of the power block, including equipment and labor.
-
Balance of Plant ($/kWe)
-
Cost per electric megawatt of power block gross capacity to account for additional costs.
-
Contingency (%)
+
Power Plant, $/kWe
+
For CSP Systems only. Cost per electric megawatt of power block gross capacity to account for the installation of the power block, including equipment and labor.
+
Heat Sink, $/kWht
+
For IPH systems only. Cost per thermal kilowatt-hour of heat sink capacity for expenses related to installation of the heat sink, including labor and equipment.
+
Balance of Plant, $/kWe for CSP, $/kWt for IPH
+
Cost per electric megawatt of power block gross capacity or thermal heat sink capacity to account for additional costs.
+
Contingency, %
A percentage of the sum of the site improvements, solar field, HTF system, storage, fossil backup, and power plant costs to account for expected uncertainties in direct cost estimates.
-
Total Direct Cost ($)
+
Total Direct Cost, $
The sum of improvements, solar field, HTF system, storage, fossil backup, power plant costs, and contingency costs.
Indirect Capital Costs
An indirect cost is typically one that cannot be identified with a specific piece of equipment or installation service.
The custom generation profile model allows you to represent a power plant using a simple model based on capacity factor and nameplate capacity, or to import hourly or subhourly electric generation data from another simulation model or measured from an operating system.
+
The Custom Generation Profile model allows you to represent a power plant using a simple model based on capacity factor and nameplate capacity, or to import hourly or subhourly electric generation data from another simulation model or measured from an operating system.
Custom Generation Profile Model
-
You can use the custom generation profile model for the following applications:
+
You can use the Custom Generation profile model for the following applications:
•Model a thermal power plant as a baseline case for comparison with renewable alternatives.
•Use power generation profiles for any type of power system from other software with SAM's financial models.
•Use measured data from an installed plant with SAM's financial models.
Custom Generation Profile - Battery Model
-
The generic battery model combines the custom generation profile model with the battery storage model from the PV battery model. You can use the generic battery model for:
-
•A battery system that responds to an hourly or subhourly generation profile from another model or from a performance monitoring program.
-
•A standalone battery system.
-
To model a standalone battery system, set the nominal capacity factor to zero (setting the nameplate capacity to zero may cause simulation errors).
+
The Custom Generation Profile - Battery model combines the Custom Generation Profile model with the battery storage model from the PV battery model. You can use the Custom Generation Profile - Battery model for a battery system that responds to an hourly or subhourly generation profile from another model or from data measured from a real system.
Combine Cases
Versions of SAM before SAM 2021.12.02 came with the "Combine Cases" macro that you could use to automatically calculate the generation profile by adding up generation data from other cases in the SAM file. This macro has been replaced by the Generate production profiles and nameplate capacity from open cases option described below.
To model curtailment, or forced outages or reduction in power output required by the grid operator, use the inputs on the Grid Limits page. The Grid Limits page is not available for all performance models.
-For the PV Battery model, battery dispatch is affected by the system availability losses. For the PVWatts Battery, Generic Battery, and Standalone Battery battery dispatch ignores the system availability losses.
+For the PV Battery model, battery dispatch is affected by the system availability losses. For the PVWatts Battery, Custom Generation Profile - Battery, and Standalone Battery battery dispatch ignores the system availability losses.
To edit the system availability losses, click Edit losses.
The Edit Losses window allows you to define loss factors as follows:
•Constant loss is a single loss factor that applies to the system's entire output. You can use this to model an availability factor.
The degradation inputs allow you to model a decline in the system's output over time due, for example, to aging of equipment.
SAM models annual degradation differently for the different performance models:
-
•AC degradation with single year simulation for all models except detailed photovoltaic, PV battery, generic battery, fuel cell, and geothermal models.
+
•AC degradation with single year simulation for all models except detailed photovoltaic, PV battery, and fuel cell model.
•DC degradation with simulation over analysis period for the detailed photovoltaic, PV battery, and fuel cell model, where degradation applies to the DC output of the photovoltaic array. Lifetime simulations allow for modeling the effect of PV module degradation on inverter power limiting losses over time, and for battery replacements where applicable.
•For the Detailed Photovoltaic and PVWatts models, when you specify a single degradation rate rather than a table of annual degradation rates, SAM applies the degradation rate linearly. For the other performance models, it applies the degradation rate to the previous year's output, so it is effectively compounded.
-
•AC degradation with simulation over analysis period for the generic battery model, where the system generates AC power. Lifetime simulations allow for modeling battery replacements.
+
•AC degradation with simulation over analysis period for the Custom Generation Profile - Battery model, where the system generates AC power. Lifetime simulations allow for modeling battery replacements.
•The geothermal model calculates the electricity generated by the system in each month over its lifetime rather than hourly or subhourly over a single year. The degradation rate is not available for geothermal systems because the model calculates the system's electrical output from year to year.
To model curtailment, or forced outages or reduction in power output required by the grid operator, use the inputs on the Grid Limits page. The Grid Limits page is not available for all performance models.
-For the PV Battery model, battery dispatch is affected by the system availability losses. For the PVWatts Battery, Generic Battery, and Standalone Battery battery dispatch ignores the system availability losses.
+For the PV Battery model, battery dispatch is affected by the system availability losses. For the PVWatts Battery, Custom Generation Profile - Battery, and Standalone Battery battery dispatch ignores the system availability losses.
To edit the system availability losses, click Edit losses.
The Edit Losses window allows you to define loss factors as follows:
•Constant loss is a single loss factor that applies to the system's entire output. You can use this to model an availability factor.
The solar elevation angel (above the horizon) that sets the operational limit of the collector field in the morning hours. When the solar elevation angle rises above this value, the collector field will begin operation.
Solar Multiple
-
Sizing the solar field of a parabolic trough or linear Fresnel system in SAM involves determining the optimal solar field aperture area for a system at a given location. In general, increasing the solar field area increases the system's electric output, thereby reducing the project's LCOE. However, during times when there is enough solar resource, too large of a field will produce more thermal energy than the power block and other system components can handle. Also, as the solar field size increases beyond a certain point, the higher installation and operating costs outweigh the benefit of the higher output.
+
Sizing the solar field of a parabolic trough or linear Fresnel system in SAM involves determining the optimal solar field aperture area for a system at a given location. In general, increasing the solar field area increases the system's electric or thermal output, thereby reducing the project's levelized cost of energy. However, during times when there is enough solar resource, too large of a field will produce more thermal energy than the power cycle or heat sink and other system components can handle. Also, as the solar field size increases beyond a certain point, the higher installation and operating costs outweigh the benefit of the higher output.
An optimal solar field area should:
-
•Maximize the amount of time in a year that the field generates sufficient thermal energy to drive the power block at its rated capacity.
+
•Maximize the amount of time in a year that the field generates sufficient thermal energy to drive the power cycle or heat sink at its rated capacity.
•Minimize installation and operating costs.
•Use thermal energy storage and backup power equipment efficiently and cost effectively.
The problem of choosing an optimal solar field area involves analyzing the tradeoff between a larger solar field that maximizes the system's electrical output and project revenue, and a smaller field that minimizes installation and operating costs.
-
The levelized cost of energy (LCOE) is a useful metric for optimizing the solar field size because it includes the amount of electricity generated by the system, the project installation costs, and the cost of operating and maintaining the system over its life. Optimizing the solar field involves finding the solar field aperture area that results in the lowest LCOE. For systems with thermal energy storage systems, the optimization involves finding the combination of field area and storage capacity that results in the lowest LCOE.
+
The levelized cost of energy (LCOE or LCOH) is a useful metric for optimizing the solar field size because it includes the amount of electricity or heat generated by the system, the project installation costs, and the cost of operating and maintaining the system over its life. Optimizing the solar field involves finding the solar field aperture area that results in the lowest LCOE or LCOH. For systems with thermal energy storage systems, the optimization involves finding the combination of field area and storage capacity that results in the lowest LCOE or LCOH.
Option 1 and Option 2
SAM's parabolic trough and linear Fresnel models provide two options for specifying the solar field aperture area on the System Design page:
-
•Option 1: You specify the solar field area as a multiple of the power block's rated capacity (design turbine gross output), and SAM calculates the solar field aperture area in square meters required to meet power block rated capacity.
-
•Option 2: You specify the aperture area in square meters independently of the power block's rated capacity.
+
•Option 1: You specify the solar field area as a multiple of the power cycle (design turbine gross output) or heat sink rated capacity (heat sink thermal power), and SAM calculates the solar field aperture area in square meters required to achieve the rated capacity.
+
•Option 2: You specify the aperture area in square meters independently of the power cycle or heat sink rated capacity.
If your analysis involves a known solar field area, you should use Option 2 to specify the solar field aperture area.
If your analysis involves optimizing the solar field area for a specific location, or choosing an optimal combination of solar field aperture area and thermal energy storage capacity, then you should choose Option 1, and follow the procedure described below to size the field.
Solar Multiple
-
The solar multiple makes it possible to represent the solar field aperture area as a multiple of the power block rated capacity. A solar multiple of one (SM=1) represents the solar field aperture area that, when exposed to solar radiation equal to the design point DNI (or irradiation at design), generates the quantity of thermal energy required to drive the power block at its rated capacity (design gross output), accounting for thermal and optical losses.
-
Because at any given location the number of hours in a year that the actual solar resource is equal to the design point DNI is likely to be small, a solar field with SM=1 will rarely drive the power block at its rated capacity. Increasing the solar multiple (SM>1) results in a solar field that operates at its design point for more hours of the year and generates more electricity.
-
For example, consider a system with a power block design gross output rating of 111 MW and a solar multiple of one (SM=1) and no thermal storage. The following frequency distribution graph shows that the power block never generates electricity at its rated capacity, and generates less than 80% of its rated capacity for most of the time that it generates electricity:
+
Note. The description in this section refers to the power cycle of a system that generates electricity. For industrial process heat (IPH) systems, the same principles apply, but are determined by the heat sink capacity rather than the power cycle capacity.
+
The solar multiple makes it possible to represent the solar field aperture area as a multiple of the power cycle rated capacity. A solar multiple of one (SM=1) represents the solar field aperture area that, when exposed to solar radiation equal to the design point DNI (or irradiation at design), generates the quantity of thermal energy required to drive the power cycle at its rated capacity (design gross output), accounting for thermal and optical losses.
+
Because at any given location the number of hours in a year that the actual solar resource is equal to the design point DNI is likely to be small, a solar field with SM=1 will rarely drive the power cycle at its rated capacity. Increasing the solar multiple (SM>1) results in a solar field that operates at its design point for more hours of the year and generates more electricity.
+
For example, consider a system with a power cycle design gross output rating of 111 MW and a solar multiple of one (SM=1) and no thermal storage. The following frequency distribution graph shows that the power cycle never generates electricity at its rated capacity, and generates less than 80% of its rated capacity for most of the time that it generates electricity:
-
For the same system with a solar multiple chosen to minimize LCOE (in this example SM=1.5), the power block generates electricity at or slightly above its rated capacity almost 15% of the time:
+
For the same system with a solar multiple chosen to minimize LCOE (in this example SM=1.5), the power cycle generates electricity at or slightly above its rated capacity almost 15% of the time:
-
Adding thermal storage to the system changes the optimal solar multiple, and increases the amount of time that the power block operates at its rated capacity. In this example, the optimal storage capacity (full load hours of TES) is 3 hours with SM=1.75, and the power block operates at or over its rated capacity over 20% of the time:
+
Adding thermal storage to the system changes the optimal solar multiple, and increases the amount of time that the power cycle operates at its rated capacity. In this example, the optimal storage capacity (full load hours of TES) is 3 hours with SM=1.75, and the power cycle operates at or over its rated capacity over 20% of the time:
Note. For clarity, the frequency distribution graphs above exclude nighttime hours when the gross power output is zero.
Reference Weather Conditions for Field Sizing
@@ -659,13 +660,13 @@
Reference Weather Conditions for
•Ambient temperature
•Direct normal irradiance (DNI)
•Wind velocity
-
The values are necessary to establish the relationship between the field aperture area and power block rated capacity for solar multiple (SM) calculations.
+
The values are necessary to establish the relationship between the field aperture area and power cycle rated capacity for solar multiple (SM) calculations.
Note. The design values are different from the data in the weather file. SAM uses the design values to size the solar field before running a simulation. During the simulation, SAM uses data from the weather file you choose on the Location and Resource page.
The reference ambient temperature and reference wind velocity variables are used to calculate the design heat losses, and do not have a significant effect on the solar field sizing calculations. Reasonable values for those two variables are the average annual measured ambient temperature and wind velocity at the project location. For the physical trough model, the reference temperature and wind speed values are hard-coded and cannot be changed. The linear Fresnel and generic solar system models allow you to specify the reference ambient temperature value, but not the wind speed. The empirical trough model allows you to specify both the reference ambient temperature and wind speed values.
-
The reference direct normal irradiance (DNI) value, on the other hand, does have a significant impact on the solar field size calculations. For example, a system with reference conditions of 25°C, 950 W/m2, and 5 m/s (ambient temperature, DNI, and wind speed, respectively), a solar multiple of 2, and a 100 MWe power block, requires a solar field area of 871,940 m2. The same system with reference DNI of 800 W/m2 requires a solar field area of 1,055,350 m2.
+
The reference direct normal irradiance (DNI) value, on the other hand, does have a significant impact on the solar field size calculations. For example, a system with reference conditions of 25°C, 950 W/m2, and 5 m/s (ambient temperature, DNI, and wind speed, respectively), a solar multiple of 2, and a 100 MWe power cycle, requires a solar field area of 871,940 m2. The same system with reference DNI of 800 W/m2 requires a solar field area of 1,055,350 m2.
In general, the reference DNI value should be close to the maximum actual DNI on the field expected for the location. For systems with horizontal collectors and a field azimuth angle of zero in the Mohave Desert of the United States, we suggest a design irradiance value of 950 W/m2. For southern Spain, a value of 800 W/m2 is reasonable for similar systems. However, for best results, you should choose a value for your specific location using one of the methods described below.
Linear collectors (parabolic trough and linear Fresnel) typically track the sun by rotating on a single axis, which means that the direct solar radiation rarely (if ever) strikes the collector aperture at a normal angle. Consequently, the DNI incident on the solar field in any given hour will always be less than the DNI value in the resource data for that hour. The cosine-adjusted DNI value that SAM reports in simulation results is a measure of the incident DNI.
-
Using too low of a reference DNI value results in excessive "dumped" energy: Over the period of one year, the actual DNI from the weather data is frequently greater than the reference value. Therefore, the solar field sized for the low reference DNI value often produces more energy than required by the power block, and excess thermal energy is either dumped or put into storage. On the other hand, using too high of a reference DNI value results in an undersized solar field that produces sufficient thermal energy to drive the power block at its design point only during the few hours when the actual DNI is at or greater than the reference value.
+
Using too low of a reference DNI value results in excessive "dumped" energy: Over the period of one year, the actual DNI from the weather data is frequently greater than the reference value. Therefore, the solar field sized for the low reference DNI value often produces more energy than required by the power cycle, and excess thermal energy is either dumped or put into storage. On the other hand, using too high of a reference DNI value results in an undersized solar field that produces sufficient thermal energy to drive the power cycle at its design point only during the few hours when the actual DNI is at or greater than the reference value.
To choose a reference DNI value:
1.Choose a weather file on the Location and Resource page.
2.For systems with storage, specify the storage capacity and maximum storage charge rate defined on the System Design page.
•For a month when the credit exceeds the total billable amount, the bill is negative, representing a cash payment to the system owner.
Net billing with carryover to next month
•Excess generation is the sum of differences between generation and load in each time step over the month. Positive values of Electricity to/from grid (kWh) time series (hourly or subhourly) results on the Data Tables tab of the Results page show excess generation.
-
•For months with excess generation, the Net billing credit ($/mo) is credited to next month's bill.
+
•For months with excess generation, the Net billing credit ($/mo) is credited to next month's bill except when Apply earned credits to current month before rollover is enabled..
+
•If Apply earned credits to current month before rollover is enabled, the credit earned this month and any remaining credit rolled over from previous month is applied to the energy charge portion of the bill for the current month. Any credit in excess of the energy portion of the bill is credited to the next month's bill, except when the current month is at the end of the true-up period, in which case the credit expires and is not applied.
•The value of the credit is determined by the sell rate. If time-of-use or tiered rates apply, excess generation accumulates over the month by time-of-use period and tier, and SAM applies the appropriate sell rate to the monthly total excess generation for each period and tier.
•For a month when the credit from the previous month exceeds the total billable amount for the current month, the remaining amount is credited to the next month.
-
•Any credit remaining at the end of the true-up period is the Net annual true-up payments ($/mo) credited to the electricity bill for the month at the end of the period.
+
•Any credit remaining at the end of the true-up period is the Net annual true-up payments ($/mo) credited to the electricity bill for the month at the end of the period unless Accrued credits expire at the end of true-up month is enabled, in which case the remaining credit expires and is not applied.
•If time-of-use periods apply to the energy rates, when the periods for next month are different than for this month, such as going from a winter month to a summer month, SAM uses the period numbers at 12 a.m., 6 a.m., 12 p.m. and 6 p.m. for the current month to determine how to assign the credit to periods in the next month.
Buy all / sell all
•All generation is sold to the grid and all consumption is purchased from the grid. There is no excess generation.
@@ -670,6 +671,8 @@
Check Use hourly (subhourly) buy rates instead of TOU rates and click Edit array to enter or import time series buy rates $/kWh. This disables the buy rate column in the Energy Charges table.
Net billing with carryover to next month
Net billing with carryover to next month is similar to net billing, except that the dollar value of excess generation is credited to the next month's bill. Specify buy and sell rates as describe above for the Net Billing option, and choose a Month for end of true-up period.
+
Check Accrued credits expire at end of true-up period if credits expire at the end of the true-up period.
+
Check Apply earned credits to current month before rollover if credits apply to the energy portion of the current month's bill, and only credits in excess of the energy charge are credited the next month. See description in Metering and Billing Definitions above for details.
Buy all /sell all
For the buy all / sell all option, specify the buy rate(s) and sell rate(s) in the Energy Charges table and use the weekday/weekend schedules to define any time-of-use periods as described below.
Note. For front-of-meter system electricity purchases, the sell rate is disabled because all electricity sales are at the power price on the Revenue or Financial Parameters page.
To model curtailment, or forced outages or reduction in power output required by the grid operator, use the inputs on the Grid Limits page. The Grid Limits page is not available for all performance models.
-For the PV Battery model, battery dispatch is affected by the system availability losses. For the PVWatts Battery, Generic Battery, and Standalone Battery battery dispatch ignores the system availability losses.
+For the PV Battery model, battery dispatch is affected by the system availability losses. For the PVWatts Battery, Custom Generation Profile - Battery, and Standalone Battery battery dispatch ignores the system availability losses.
To edit the system availability losses, click Edit losses.
The Edit Losses window allows you to define loss factors as follows:
•Constant loss is a single loss factor that applies to the system's entire output. You can use this to model an availability factor.
•Variable operating cost, $/kWh (VOC), or operations and maintenance costs per unit of annual electricity production.
•Fixed charge rate (FCR)
•Annual electricity production, kWh (AEP)
-
The LCOE Calculator uses the following equation to calculate the LCOE:
+
The LCOE Calculator uses the following simple equation:
The fixed charge rate is the revenue per amount of investment required to cover the investment cost. For details, see pp. 22-24 of Short W et al, 1995. Manual for the Economic Evaluation of Energy Efficiency and Renewable Energy Technologies. National Renewable Energy Laboratory. NREL/TP-462-5173. (PDF 6.6 MB)
To include the effect of incentives in this simple fixed charge rate method, reduce the TTC, FOC, or VOC as appropriate. For example, you could account for a 30% investment tax credit by reducing the TCC by 30%.
The LCOH Calculator uses a similar approach to the LCOE Calculator to calculate the levelized cost of heat for a system that produces heat instead of generating electricity.
+
The LCOH Calculator uses a simple method to calculate a project's levelized cost of energy (LCOH) using only the following inputs:
+
•Capital cost, $ (TCC), or installed capital costs.
+
•Fixed annual operating cost, $ (FOC), or operations and maintenance costs.
+
•Variable operating cost, $/kWh (VOC), or operations and maintenance costs per unit of annual electricity production.
+
•Fixed charge rate (FCR)
+
•Annual electricity production, kWh (AEP)
+
The LCOH Calculator uses the following simple equation:
+
+
The fixed charge rate is the revenue per amount of investment required to cover the investment cost. For details, see pp. 22-24 of Short W et al, 1995. Manual for the Economic Evaluation of Energy Efficiency and Renewable Energy Technologies. National Renewable Energy Laboratory. NREL/TP-462-5173. (PDF 6.6 MB)
+
To include the effect of incentives in this simple fixed charge rate method, reduce the TTC, FOC, or VOC as appropriate. For example, you could account for a 30% investment tax credit by reducing the TCC by 30%.
+
This method is an alternative to the cash flow method used by SAM's other financial models. The fixed charge method is appropriate for very preliminary stages of project feasibility analysis before you have many details about the project's costs and financial structure. It also useful for large-scale studies of market trends, such as those used for the NREL Annual Technology Baseline (ATB) study.
+
Retail Electricity Rate
+
SAM's industrial process heat (IPH) models calculate the total parasitic electric load in each time step to account for electricity required for HTF pumps and collector tracker drives. The retail electricity is the cost of electricity to meet this load.
+
Electricity rate, $/kWh
+
The retail rate of electricity for purchases of electricity to meet parasitic loads.
+
SAM treats this cost as an operating cost in the LCOH calculation. The total cost of electricity is
You can enter the capital and fixed operating cost either as dollar amounts or in dollars per kilowatt of system capacity.
+
Note. For the marine energy models, enter the capital and operating costs on the Capital Costs pages. SAM calculates the total capital cost and operating cost from the values on the Capital Costs pages.
+
System capacity
+
The renewable energy system's nameplate capacity. Its value depends on the performance model you use for the simulation, and is shown here for reference when you enter costs in $/kW.
+
Enter costs in $
+
Choose this option to enter the capital cost and annual fixed operating costs as dollar amounts. Not available for marine energy models.
+
Enter costs in $/kW
+
Choose this option to enter the capital cost and annual fixed operating costs in dollars per kilowatt of system capacity. The system capacity depends on the performance model you choose. Not available for marine energy models.
+
Capital cost
+
The project's total investment cost, or installed capital costs. For the marine energy models, this is the sum of the costs on the Capital Costs pages.
+
Fixed operating cost
+
Annual operating and maintenance costs that do not vary with the amount of electricity the system generates. For the marine energy models, this is the sum of the costs on the Capital Costs pages.
+
Variable operating cost
+
Annual operating and maintenance costs in dollars per kilowatt-hour that vary with the amount of electricity the system generates.
+
Note. The LCOH calculator includes the cost of electricity to meet parasitic loads in the total operating cost.
+
Summary
+
The Summary values are the inputs to the LCOH equation shown above. SAM calculates these values from the inputs you specify. You cannot edit these values directly.
+
Fixed charge rate
+
The project fixed charge rate is an annual return as a fraction of the capital cost, or revenue per amount of investment required to cover the investment cost. It is either the value you enter under Financial Assumptions, or the value SAM calculates from the financial details you enter.
+
Capital cost
+
The total investment cost in dollars. It is either the value you entered or a value that SAM calculates based on the value you enter in dollars per kilowatt.
+
Fixed operating cost
+
The fixed annual operating cost in dollars. It is either the value you enter or a value that SAM calculates based on the value you enter in dollars per kilowatt.
+
Variable operating cost
+
The variable annual operating cost in dollars per kilowatt-hour that you enter.
+
Financial Assumptions
+
The fixed charge rate represents details of the project's financial structure. You can either enter the value directly, or enter project financial details and SAM calculates the value.
+
Enter fixed charge rate
+
Choose this option to enter the fixed charge rate.
+
Calculate fixed charge rate
+
Choose this option to have SAM calculate the fixed charge rate from a set of financial assumptions. The SAM uses the following equation to calculate the value from the capital recovery factor, project financing factor, and construction financing factor (see below for all equations):
+
+
Fixed charge rate
+
The project's fixed charge rate. Note that the value is a factor (between 0 and 1) rather than a percentage.
+
Analysis period
+
The number of years that the project will generate electricity and earn revenue.
+
Inflation rate
+
The annual inflation rate over the analysis period. To exclude inflation from the analysis, set the inflation rate to zero.
+
Internal rate of return
+
The project's annual nominal rate of return on equity requirement.
+
Project term debt
+
The size of debt as a percentage of the capital cost.
+
Nominal debt interest rate
+
The annual nominal debt interest rate. SAM assumes that the debt period is the same as the analysis period.
+
Effective tax rate
+
The total income tax rate. For a project that pays both federal and state income taxes, where the state income tax is deducted from the federal tax, you can calculate the effective tax rate as:
+
+
To exclude income tax from the analysis, set the effective tax rate to zero.
+
Depreciation schedule
+
The annual depreciation schedule. The depreciation basis equals the project's capital cost.
+
To enter a depreciation schedule, click the small blue and grey button next to the Edit button so that the button becomes active. Then click Edit to open the Edit Schedule window. In the Edit Schedule window, for Number of values, enter the number of years in the depreciation schedule, and then enter the depreciation percentage for each year in the Value table.
+
For MACRS 5-yr depreciation the table should look like this:
+
+
To exclude depreciation from the analysis, set the depreciation percentage(s) to zero.
+
Annual cost during construction
+
The annual construction cost as a percentage of the project's capital cost. If the construction period is one year or less, enter a single value. If it is more than one year, enter a schedule of annual percentages.
+
To enter a construction cost schedule, click the small blue and grey button next to the Edit button so that the button becomes active. Then click Edit to open the Edit Schedule window. For Number of values, enter the number of years in the construction period, and then enter a cost (as a percentage of the capital cost) for each year in the Value table.
+
To exclude construction financing costs from the analysis, set the annual cost during construction to 100%, and the nominal construction interest rate to zero.
+
Nominal construction interest rate
+
The annual interest rate on construction financing.
+
Capital recovery factor (CRF)
+
SAM calculates this value from the inputs you specify as described below.
+
Project financing factor (PFF)
+
Factor to account for project financing costs. SAM calculates this value from the effective tax rate and depreciation schedule, as described below.
+
A value of "NaN" (not a number) indicates that the effective tax rate is 100%. Change the tax rate to something less than 100% to correct the problem.
+
Construction financing factor (CFF)
+
Factor to account for construction financing costs. SAM calculates the value from the construction cost schedule, effective tax rate, and construction interest rate, as described below.
+
A value of zero will cause the FCR to be zero, and is caused by setting the annual cost during construction to zero. If you want to exclude construction financing (CFF = 1), you should set the annual cost during construction to 100%, and the nominal construction interest rate to zero.
+
Equations for FCR Calculation
+
When you use the Calculate fixed charge rate option, SAM uses the following equations to calculate the financing factors.
+
Nomenclature
+
c = Construction year
+
C = Construction period in years
+
CON = Construction schedule
+
DF = Project term debt fraction
+
i = Inflation rate
+
n = Analysis year
+
N = Analysis period
+
IRR = Nominal return on investment
+
NINT = Nominal debt interest rate
+
PVDEP = Present value of depreciation
+
RINT = Real debt interest rate
+
RROE = Real return on investment
+
TAX = Effective tax rate
+
WACC = Weighted average cost of capital (real)
+
+
The capital recovery factor (CRF) is a function of the weighted average cost of capital (WACC) and analysis period (N):
+
+
Where:
+
+
+
+
+
The project financing factor (PFF) is a function of the effective tax rate and depreciation schedule:
+
+
Where:
+
+
The construction financing factor (CFF) is a function of the construction cost schedule, effective tax rate, and nominal construction financing interest rate:
