Editorial policy and corrections

Anyone who spends 500 euros on a balcony system or 15,000 euros on a roof after reading this site relies on our figures. So here is where each one comes from and what happens when one is wrong.

Responsibility

Content and calculators are the responsibility of Radif Partners. Contact: kontakt@solarrechnen.de.

Primary sources only

European Commission PVGIS (Joint Research Centre): radiation and yield at any location;
Federal Network Agency (Bundesnetzagentur): feed-in rates by period, the Market Master Data Register, SMARD market data;
gesetze-im-internet.de: EEG 2023, MaStRV, Income Tax Act, VAT Act, Civil Code and Condominium Act as in force;
German Bundestag: bills as printed papers, never press reports about them;
Eurostat and Destatis: household electricity prices, municipalities with coordinates and population;
HTW Berlin: metered load profiles of 74 households.

Retailer pages, installer blogs and other calculators are not sources, even when they rank first.

Checks before every release

Automated tests compare feed-in rates with the Federal Network Agency table and location values with direct PVGIS queries, and check the energy balance of every calculation. A deviating value stops the release.

Rhythm

A scheduled job reloads rates, prices, market data and register counts every week. All texts are reviewed at least every 12 months and whenever the law changes, at the latest when the EEG 2027 reform takes effect. Drafts are described as drafts and never calculated as law.

Handling errors

Check against the primary source.
Fix in the data file or calculator, plus a new test that catches the error in future.
New date on every page; a substantive correction is noted on the page concerned.

Independence

No money from panel makers, retailers, installers, energy suppliers or comparison portals. No product recommendations, no affiliate links.

See also How we calculate. Version: 2026-10-15.