PV Battery Operating costs#
Operating costs are annual expenditures on equipment and services that occur after the system is installed. You can specify separate costs based on the nameplate capacity and annual generation of the photovoltaic system and battery.
Note
The operating cost inputs are in Year 1 dollars. SAM applies the inflation rate from the Financial Parameters page to calculate the operating cost in each year of the cash flow. If you specify a non-zero escalation rate for an operating cost category, it applies both the inflation rate and escalation rate.
Note
For financial models with reserve accounts on the Financial Parameters page, you can use either the operating costs or the major equipment replacement reserve accounts for the cost of major equipment replacements.
For expenses such as component replacements that occur in particular years, you can use an annual schedule to assign costs to individual years.
PV#
The PV operating costs account for the cost of operating and maintaining the photovoltaic system, including modules, inverters, and balance-of-system components.
- Capacity
The nominal capacity of the photovoltaic array in DC kilowatts from the System Size page .
- Fixed annual cost, $/yr
A fixed annual cost that applied to each year in the project cash flow to account for photovoltaic system operating costs.
- Fixed cost by capacity, $/kWdc-yr
A fixed annual cost based on the photovoltaic system’s capacity .
- Variable cost by generation, $/MWhac
A variable annual cost based on the annual AC generation of the photovoltaic system, not including energy discharged by the battery or generated by the fuel cell.
Battery#
Battery operating costs account for the cost of operating and maintaining equipment associated with the battery, such for maintaining battery cells, control equipment, and wiring. It may also include HVAC equipment for heating and cooling the battery environment, and battery replacements.
- Capacity
The battery’s nominal storage capacity in DC kilowatt-hours from the Battery Storage page.
- Fixed annual cost, $/yr
A fixed annual cost that applied to each year in the project cash flow to account for battery operating costs.
- Fixed cost by capacity, $/kWhdc of battery storage capacity
A fixed annual cost based on the battery’s storage capacity.
- Variable cost by generation, $/MWhac of electricity discharged by the battery
A variable annual cost based on the total annual electricity discharged by the battery in AC megawatt-hours.
- Replacement cost, $/kWdc of battery storage capacity
The replacement cost in Year 1 dollars per unit of battery capacity. SAM uses the inflation rate from the Financial Parameters page to calculate the replacement cost in the replacement year.
Note
To include battery replacements costs in your analysis, be sure to choose a battery replacement option on the Battery Storage page.
Escalation Rate#
For each operating cost category, you can specify an optional annual Escalation Rate to represent an expected annual increase or decrease in operating cost above the annual inflation rate specified on the Financial Parameters page.
Specify an escalation rate of zero for an operating cost that increases annually at the rate of inflation, a positive escalation rate for a cost that increases at a higher rate than the inflation rate, or a negative escalation rate for a cost that increases at a lower rate than the inflation rate. (Set the inflation rate to the negative value of the inflation rate for a cost that does not increase with inflation.)
Land Lease costs#
For front-of-meter projects and performance models that estimate a land area, you can model land lease payments that are treated as an operating cost in the project cash flow.
Note
Land lease costs are not available for the distributed behind-the-meter financial models: Residential, Commercial, or Third Party Ownership models.
- Land area estimate, acres and ha
The calculated estimate of land area required for the project from the System Design page for the photovoltaic models, or from the Solar Field or Heliostat Field page for concentrating solar power (CSP) models.
- Annual land lease cost, $/acre or $/ha
The annual lease cost. Choose the units to specify the cost in either $/acre or $/hectare. You can specify the cost in Year 1 dollars with an optional escalation rate, or click
to specify the cost by year.- Land lease escalation rate
If you specify the land lease cost as a single value, you can specify an escalation rate to model land lease payments that increase annually. SAM applies the escalation rate in addition to the inflation rate on the Financial Parameters page.
Using Annual Schedules to Specify Operating costs in Specific Years#
SAM allows you to operating costs either as a single annual cost, or as an annual schedule or table of costs. An annual schedule makes it possible to assign costs to particular years in the analysis period. Annual schedules can be used to account for component replacement costs and other periodic costs that do not recur on a regular annual basis.
You choose whether to specify an operating cost as a single annual value or an annual schedule with the grey and blue button next to each variable. SAM uses the option indicated by the blue highlight on the button: A blue highlighted “Value” indicates a single, regularly occurring annual value. A blue highlighted “Sched” indicates that the value is specified as an annual schedule.
For example, to account for component replacement costs, you can specify the fixed annual cost category as an annual schedule, and assign the cost of replacing or rebuilding the component to particular years. For a 30-year project using a component with a seven-year life, you would assign a replacement cost to years seven, 14, and 21. Or, to account for expected improvements in the component’s reliability in the future, you could assign component replacement costs in years seven, 17, and 27. After running a simulation, you can see the replacement costs in the project cash flow in the appropriate column under Operating Expenses. SAM accounts for the operating costs in the other economic metrics including the levelized cost of energy and net present value (NPV).
Note
If you use the annual schedule option to specify equipment replacement costs, SAM does not calculate any residual or salvage value of system components based on the annual schedule. SAM calculates salvage value separately, using the salvage value you specify on the Financial Parameters page.
Dollar values in the annual schedule are in nominal or current dollars. SAM does not apply inflation and escalation rates to values in annual schedules.
The following procedure describes how to define the fixed annual cost category as an annual schedule. You can use the same procedure for any of the other operation and maintenance cost categories.
To assign component replacement costs to particular years:
In the Fixed Annual Cost category, note that the “Value” label of the grey and blue button is blue indicating that the single value mode is active for the variable.
In this case, SAM would assign an annual cost of $284 to each year in the project cash flow.
Click the button so that “Sched” label is highlighted in blue. SAM replaces the variable’s value with an Edit button.
Click Edit to open the Edit Schedule window.
In the Edit Schedule window, use the vertical scroll bar to find the year of the first replacement, and type the replacement cost in current or constant dollars for that year.
To delete a value, select it and press the Delete key on your keyboard.
Note
You must type a value for each year. If you delete a value, SAM will clear the cell, and you must type a number in the cell or SAM will consider the schedule to be invalid. Type a zero for years with no annual costs.
When you have finished editing the schedule, click Accept.
Because you must specify an operating cost category as either an annual cost or annual schedule, to assign both a recurring annual fixed cost and periodic replacement cost, you must type the recurring cost in each year of the annual schedule, and for years with replacement costs, type the sum of the recurring and replacement costs.