Solar NPV calculator

Net present value from year-by-year cash flows, before tax, with no incentive. A design aid, not financial advice. Decimal commas are accepted.

System size (kW dc) System cost (USD per W) Year-1 yield (kWh per kW) Degradation (% per year) Used on site (%) Import rate (USD per kWh) Export rate (USD per kWh) Import rate escalation (% per year) O&M (USD per kW, year 1) Inflation for O&M and replacement (%) Inverter replacement (USD, today's money) Replacement year (0 = none) Discount rate (% nominal) Horizon (years, 1 to 50)

System cost (USD)-

Year-1 net saving (USD)-

NPV at discount rate (USD)-

Break-even rate (IRR)-

NPV at rate minus 2 points (USD)-

NPV at rate plus 2 points (USD)-

Real discount rate-

NPV in real terms (check, USD)-

Model: year-t saving = output x (share used x import rate + exported share x export rate); import rate escalates from year 2 and the export rate stays flat. O&M and the replacement rise with inflation. Cost at year 0, flows at year end, no tax. The real rate is (1 + nominal) / (1 + inflation) - 1. The check deflates every flow by inflation and discounts at the real rate, so it must equal the NPV.