Terms

The rules for using SolarPosition.org, its calculators and the embed card. Short, because the service is free and needs no account.

1. Operator

SolarPosition.org is operated by SolarPosition.org (the “Administrator”). Contact: [email protected]. By using the site you accept these terms; if you do not accept them, please do not use it.

2. The service

SolarPosition.org computes the position of the sun, daylight, solar panel angles, peak sun hours, off-grid sizing examples and solar forecasts for places on Earth. It is free of charge, needs no registration and is paid for by advertising (see the privacy policy). We may change, extend or pause any part of the service, for example for maintenance.

3. What you may do

Use the site and its results for any lawful purpose, private or commercial.
Quote numbers and short passages with a link to the page they come from.
Put the free embed card for a place on your own website, unchanged and with its link.

4. What you may not do

Overload the site with automated requests; cache what you fetch.
Copy the site as a whole or large parts of it, or present its pages as your own.
Try to break into, disturb or test the security of the service without our written permission.
Hide, cover or click the ads artificially, or use tools that generate invalid ad traffic.

We may block addresses that break these rules.

5. Accuracy — not engineering advice

Sun positions are computed with a high-precision algorithm (NREL SPA). Yield, sizing and forecast figures are estimates from long-term climate averages and weather models; any real year, site and installation will differ. The results are information, not professional advice. Electrical installations must be designed and built by qualified people in line with local regulations and the manufacturers' instructions.

6. Liability

The service is provided “as is” and “as available”, without warranty of any kind. To the extent the law allows, the Administrator is not liable for losses resulting from the use of the service or from decisions based on its results, nor for interruptions and errors. Nothing in these terms limits liability that cannot be limited by law, in particular for intent, gross negligence or under mandatory consumer protection rules.

7. Advertising and links

Ads are selected and delivered by Google AdSense. We do not endorse the products advertised and are not responsible for the content of advertisers' or other external websites linked from here.

8. Data sources and licences

Places: GeoNames, Creative Commons Attribution 4.0 (CC BY 4.0); the towns of 15,000 people or more, with web addresses added by SolarPosition.org.
Climate: the data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division; monthly climatology retrieved in August 2026, interpolated by SolarPosition.org.
Weather forecasts: Deutscher Wetterdienst (DWD), ICON-EU open data, Creative Commons Attribution 4.0 (CC BY 4.0); combined from several model runs and converted to solar panel output by SolarPosition.org.
Time zones: IANA time zone database, public domain.

The credits each source asks for, the links to the sources and the licence texts are listed under Data sources and licences.

Text, charts, design and code of this site © 2026 SolarPosition.org. Fonts: Big Shoulders Display, Instrument Sans and Instrument Serif under the SIL Open Font License; icons: Material Symbols (Apache License 2.0).

9. Changes and law

We may update these terms; the current version is always on this page with its date at the top. These terms are governed by the law of the country where the Administrator is established; if you are a consumer, the mandatory protections of the country where you live remain unaffected.

10. Contact

Questions, corrections and reports of errors in our data are welcome at [email protected].