Solar ROI Resources

Guides for reading PV Yield results and building better solar investment assumptions.

These resources explain the assumptions behind solar payback, IRR, NPV, LCOE, weather data, tariff values, and production losses. They are written for users who want to check a proposal before paying for detailed engineering or financial advice.

Start with the calculator, then use the guides below to replace generic defaults with project-specific inputs. The most important improvements usually come from using a complete installed cost, a realistic self-consumption ratio, the correct utility tariff, and conservative loss assumptions.

The guides are also useful when two proposals show different returns. Work through the relevant topic, identify which assumption changed, then rerun the calculator with the same inputs so the comparison is based on the project economics rather than presentation style.

• Global Solar ROI CalculatorInteractive calculator for PV payback, IRR, NPV, LCOE, losses, and local tariff assumptions.
• Solar ROI Data SourcesWeather APIs, geocoding, tariff defaults, installed-cost assumptions, and when to override defaults.
• Solar ROI Calculation FormulasGeneration, losses, degradation, revenue, payback, NPV, IRR, LCOE, and sensitivity formulas.
• How to Use a Solar ROI CalculatorInputs, outputs, and common mistakes when comparing PV projects.
• LCOE Explained for Solar ProjectsHow levelized cost of electricity helps compare project economics.
• IRR and NPV for Solar CashflowsWhy two profitable projects can have different financial profiles.
• PVGIS vs NASA POWER Weather DataHow irradiation data choices affect generation estimates.
• Solar Payback AssumptionsWhich assumptions move payback the most.
• Solar Losses GuideShading, soiling, thermal, wiring, inverter, and availability losses.
• Feed-in Tariff GuideHow export value changes project revenue.
• Residential Solar ChecklistQuestions to answer before trusting a rooftop solar quote.