Dear Sasha,
On the Payment Incentives page, you can use the Production Based Incentive (PBI) inputs to model incentives such as the SREC that are paid on a $/kWh basis.
To model a PBI that decreases by 5% annually, you can enter a negative value for the PBI's escalation rate. (Be sure to specify the number of years under Term so that SAM correctly models the incentive.)
You can also use an annual schedule to specify the annual PBI explicitly. See "Specifying Year-by-Year Values for PBI Values" in the Payment Incentives Help topic for details.
You can verify SAM's calculation of the PBI amount in the project cash flow: After running simulations, on the Results page, click Base Case Cash Flow and scroll down to see the PBI rows in the cash flow table.
Best regards,
Paul.