homeassistant

So there is a calculation for what time the sun is at a particular angle in the sky which will be relative to your area and factors in the time of year etc. You could use that as it will give you a very specific to your area mathematical answer to when you should close your shades. This is a good start. If you mix that with a light sensor and set minimums that will get you the rest of the way there (no sense run blocking lightning a cloudy day.) You can just use a light sensor but it will be more erratic if you don't correct for weather and seasonal light levels.

The rest is personal to how sensitive to light changes and seasonal settings you apply to it.

As far as the physical control goes - there are several commercial devices available as well as diy solutions involving motors and 3d printing on YouTube.

Light sensor threshold, and a rule to trigger the blinds. Pretty simple.

Hey, I have a Shelly window/door sensor on my bifold door. It includes a lux and temperature sensor, which i’m using to close the blinds (luxaflex/hunter douglas) if the temperature exceeds a certain level along with a high light level.

In practice where I live it is easier to close the blinds based on the current outside temperature, but the window/door sensor makes a good second check. it also prevents the blinds from operating if the door is open!

Just a few ideas for very easy math:

Start with the sunrise and sunset times. You can have them automatically for your location.

Calculate the middle between these: this is your best "noon" time (free of DST etc).

Calculate the duration between these: the longer it is, the warmer.

If your goal is just to prevent glare from direct sunlight? Maybe a purely passive diffuser is what you're looking for

It's not clear to me if you have photovoltaic panels and can use the data from them or not.