Privacy
Short version: there are no accounts, no tracking cookies, and nothing you type into a calculator is stored. Of what you type, only your roof's angle and direction ever leave your browser, and only if you enter them (see below).
What is not collected
- No accounts and no sign-up, so there is no name, address or password to hold.
- No advertising, no third-party trackers and no cookies used to identify you or follow you between sites.
- The figures you enter into either calculator, mileage, prices, roof size, consumption, stay in your browser. They are worked out on your own device and never saved. Reload the page and they are gone.
What does leave your browser
Server logs
The site is hosted on Vercel, which records ordinary web server information for each request: the page asked for, the time, the browser string, and the IP address it came from. This is how any website works and it is what makes serving a page possible. Those logs are Vercel's and are kept for a limited period under their own policy.
Visitor counts
Vercel Web Analytics counts page views so I can see whether anyone is using this. It is deliberately the cookieless kind: it records which page was viewed, roughly where in the world from, and what sort of browser and device, all aggregated. It does not set a cookie, does not build a profile, and does not follow you to other sites. I cannot see individual visitors in it.
The PVGIS lookups
Two settings in the solar calculator ask PVGIS, a service of the European Commission, for figures it does not keep on this site. If you switch on I know my roof's angle and direction, the slope and direction you set are sent, together with the coordinates of the city you picked, and PVGIS returns an irradiation figure for that orientation. If you switch on Work it out hour by hour, the city's coordinates are sent, with your slope and direction if you set them, and PVGIS returns hourly solar output for that place. Nothing else goes with either request: not your consumption, not your car, not your prices. Those stay in your browser.
The requests go through this site's own server rather than from your browser, so PVGIS does not see your address. The coordinates are the city's, from a public gazetteer, not yours: nothing here asks for or uses your actual location.
Where the data on the site comes from
Everything the calculators draw on, solar yield, electricity and fuel prices, grid carbon intensity, is public data from European sources, stored in a database that holds no personal information of any kind. Each source is named on the methodology page.