This is a free calculator you can put on your own page. Your readers type a zip code, postcode or city name, and get the best fixed tilt for that location plus today's angle, worked out from latitude. It is one iframe, it loads no tracking, and it costs you nothing.
Paste this where you want the calculator to appear:
<iframe src="https://solarific.co/embed"
width="100%" height="330"
style="border:0;max-width:420px"
title="Solar panel angle calculator"
loading="lazy"></iframe>To open it on a particular place, add ?q= and the location, for example https://solarific.co/embed?q=80202 or https://solarific.co/embed?q=Bristol. That is useful when the surrounding article is about one city.
The widget is light by default, because an iframe cannot see the page around it and guessing wrong looks worse than a safe default. If your site is dark, add &theme=dark. If you would rather it follow the reader's own system setting, use &theme=auto.
<iframe src="https://solarific.co/embed?theme=dark"
width="100%" height="330"
style="border:0;max-width:420px"
title="Solar panel angle calculator"
loading="lazy"></iframe>Nothing you have to do. The widget carries a small "Calculated by Solarific" line, and that is the whole arrangement. You are free to remove it, and you are free to keep the widget if you do. We are not going to ask you to add a keyword-stuffed link, because that is the kind of thing search engines discount anyway.
The fixed tilt comes from a curve fitted to PVGIS v5.2 optimal-slope data for 52 cities between 1 and 69 degrees of latitude, accurate to about 3.4 degrees RMSE against that reference. Today's angle comes from the sun's declination for the current day of the year. Latitude cannot capture local climate, so a cloudy place and a clear place at the same latitude get the same answer; treat the number as a good starting point rather than a site survey.
The full method is on the guide page, and every city we cover has its own page with monthly figures.