I'd like to pull in my awning if my house's shadow has reached a point where the awning has no use any more. The house is almost perfectly aligned in a North-South direction, the garden with the awning is in the east.
My home automation (fhem) offers a module that gives me a variety of astronomic parameters, based on my location and altitude:
"SunAlt": -3.3, "SunAz": 309.5, "SunDec": 22.3, "SunDiameter": 31.5, "SunDistance": 151752013, "SunDistanceObserver": 151752409, "SunHrsInvisible": "08:10", "SunHrsVisible": "15:49", "SunLon": 72.7, "SunRa": "04:47", "SunRise": "05:16", "SunSet": "21:05", "SunSign": "Zwillinge", "SunSignN": 2, "SunTransit": "13:10",
Is it enough to target sun's altitude above the horizon? I would think so, but I'm not sure... Currently I'd withdraw the awning when sun's altitude goes below 54⁰.
Edit: Sorry, I seem to have written my question in a very unclear way. Here's more information:
I know my location, at least with GPS precision. Given that location, fhem's astro module gives me all kind of information about sun, moon,...
I have a patio that's to the east of my N-S aligned house. The house is a row house, so for my purpose it's long enough that only the roof is interesting for the shadow.
Sun shines onto the patio in the morning until (currently) something like 15:00. I tend to make shadow with the awning in the morning. After 15:00, the patio is in the shadow of the house and I don't need the awning any more and I would like to remove the awning automatically.
I looked at fhem's astro module exactly at the time when the shadow was far enough on the patio that I could remove the awning. I took the "Sun altitude" value (54⁰) and now the awning is removed when the sun reaches an altitude of 54⁰
This was some days ago and I think this might not be good enough: it seems as if the shadow is extending more and more until the awning is removed. Or the other way round: It seems that I have to adjust the 54⁰ to, maybe, 50⁰ now to get the right timing.