Hi Nada,
The Specify IRR Target option requires that you specify the purchase price of electricity for freeze protection and other night-time parasitic loads on the Electricity Purchases input page instead of using the PPA price for the purchase price. This is because for the Specify IRR Target option, SAM does not know the PPA price at the beginning of the simulation, so it cannot calculate the cost of electricity purchases unless you set the purchase price.
To set the electricity purchase price:
1. Go to the Electricity Purchases page.
2. Choose Use retail electricity rate(s).
3. Under Energy Charges, set the Buy rate to the electricity purchase price. You can set this price to a retail rate, or to an estimate of the PPA price. After running a simulation to calculate the PPA price based on the target IRR, you can change the buy rate to the calculated PPA price and run another simulation to generate the final cash flow.
Best regards,
Paul.