Hello,
I'm not sure there is an error in SAM's cash flow calculation.
The "energy value" is the revenue from electricity sales, which SAM treats as taxable. So the net after-tax energy value is not $25K, but $25K * (1-0.3869) = $15K, where 0.3869 is the effective tax rate.
Did you try "Send to Excel with equations?" (It's only available in Windows, so nevermind if you're using a Mac.) You can use that for the utility IPP, commercial and residential financing options to trace through the financial model calculations.
Here are the details of how SAM calculated the $346 after-tax cash flow for year 20 in your file. First, here's the general equation:
After Tax Cash Flow = Energy Value * (1 - Effective Tax Rate)
- Operating Costs
- Total Debt Payment
+ Total PBI
+ State Tax Savings
+ Federal Tax Savings
Now, with values from your file for Year 20:
After Tax Cash Flow = $25,224 * (1 - 0.3869)
- $3,771
- $13,071
+ 0 [no PBI]
+ $316
+ $1406
= $345 [slight difference due to rounding]
Best regards,
Paul.