Methodology updated October 2025
SolarHomeTech methodology
PVGIS irradiance, ECB FX rates, 2,500 kWh per person demand, EUR 1,200/kW capex, 20-year life. Every assumption is listed so you can trust the rooftop solar calculator.
- PVGIS TMY irradiance plus roof geometry drive production.
- Default demand is 2,500 kWh per person and editable in the form.
- Capex assumes EUR 1,200 per kW with a 20-year horizon.
- ECB FX rates convert EUR savings to local currency.
Data source
Irradiance and production
PVGIS typical meteorological year irradiance plus roof geometry estimate monthly and annual PV output.
- API: PVGIS pvcalc monthly and annual outputs with default 14% system losses unless the user overrides tilt/azimuth.
- Array sizing uses 1.75 m2 per kWdc inside the usable roof area you provide.
- Shading slider applies extra loss so AC kWh reflect local obstacles.
Demand
Consumption estimate
Demand defaults to 2,500 kWh per person per year and scales with your household size.
- Users can override people count; EV loads add to household demand in the analyzer.
- Self-consumption share compares modeled PV output to this demand profile.
- Results show annual coverage plus monthly balance in the main analyzer.
Capex + cash flow
Financial model
Baseline capex is EUR 1,200 per kW installed with a 20-year evaluation horizon.
- Upfront cost scales linearly with system size derived from roof inputs.
- Annual value combines self-consumption at the retail tariff and exports at the feed-in ratio you choose.
- Payback is simple cumulative cash flow without degradation or inflation for transparency.
FX + tariffs
Currency conversion
European Central Bank reference rates convert EUR values to local currency.
- Tariff datasets load the latest residential average by country; if missing we fall back to 0.30 EUR/kWh.
- Custom tariffs override the average for both self-consumed and exported energy.
- If a currency is unsupported, EUR values are displayed as-is.
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