The payback period, real and nominal LCOE, and solar water heating outputs are described in SAM's Help system. I will explain the metrics below, but you can read more detailed descriptions in Help.
1. The payback period is the year that the cumulative payback cash flow switches from negative to positive, where:
Payback in Year Zero = Total IBI - Total CBI - Total Installed Cost
Payback in Year n>0 = After Tax Cash Flow in Year n + Debt Interest Payment in Year n × (1 - Effective Tax Rate) + Debt Repayment in Year n
After Tax Cash Flow in Year n>0 = After Tax Cost in Year n + Energy Value in Year n × (1 - Effective Tax Rate)
After Tax Cost in Year n>0 = Operating Income + State Tax Savings + Federal Tax Savings + Total PBI - Debt Total Payment
The cumulative cash flow for each year is the sum of the current year's payback cash flow and the previous year's cumulative payback cash flow.
2. The real LCOE is a constant dollar, inflation-adjusted value. The nominal LCOE is a current dollar value.
3. The annual energy saved for the solar water heating model is:
Annual Energy Saved = ( Aux Without Solar - Aux With Solar - Pump Power ) × Availability
4. I do not have a copy of the book you mention. Can you attach an image of the schematic to a reply to this forum topic?
Best regards,
Paul.
