01Irradiance
PVGIS satellite data
The Photovoltaic Geographical Information System from the EU Joint Research Centre provides site-specific irradiance for your postal code — adjusted for tilt and azimuth.
Independent solar calculator
Does your roof pencil out?
Or not?
Before you sign the installer's quote: a transparent second opinion, based on PVGIS satellite data, the HTW Berlin self-consumption model, and current feed-in tariffs. Runs in your browser. No signup, no data collection.
4 data sourcesPVGIS · HTW · Fraunhofer · BDEW
Methodology →Example run / Cumulative savings over 25 years
Single-family · 8.4 kWp · South 30° · Munich · no battery
Source: OpenSolarCheck · PVGIS · HTW Berlin · Fraunhofer ISE
What we don't collect
Your inputs stay in your browser's session storage. Nothing leaves your device — except the PVGIS irradiance call to the EU Commission.
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Cookies
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Third-party trackers
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Sign-ups
100 %
Computed in browser
Methodology
How the math is built
Three established models, applied in sequence. No heuristics, no gut-feel guesswork.
02Self-consumption
HTW Berlin model
The Quaschning/Weniger polynomial on top of the BDEW H0 standard load profile. Accounts for battery efficiency and household draw over the year.
03Economics
25-year NPV
Investment costs per Fraunhofer ISE, EEG feed-in tariff, electricity price growth 3 %/yr, module degradation 0.5 %/yr, discount rate 3 %.
Who this is for
01
Homeowner before the installer meeting
Second opinion on a quote already in hand
02
Energy advisors & installers
Credible short analysis for clients, embeddable
03
Students & researchers
Transparent, open calculation chain
FAQ
Common questions
Five steps. No signup.
Location, roof, system, consumption, battery. See payback, NPV, and CO₂ in about two minutes.