Velux/Rollershutter management based on sun exposure

Hi all,

I need some suggestions/idea how to manage my velux/rollershutter based on sun exposure/light. I would like to create a rule, to have enough light but not direct sun inside my house during the summer (to reduce the temperature as much as I can), and changing the % of opening based if the window is exposed at East/South/West, based on time during the day, sun elevation/azimuth, … And of course, the opposite during the winter.

Suncalc.org should be also my friend.

Any idea? someone already implemented something like this? Any input?

thanks for any suggestion

Andrea

Maybe better buy a light sensor to really know if sun is shining or if it is cloudy …

Oh oh, I can be of use! No more lurking in the shadows, taking notes of other peoples awesome stuff.
Now it is my time to shine!
So, erg. What I did was, I bought a xiaomi light sensor, and stuck it behind the window (first mistake).
When my wifie started complaining about too much light in her face (second mistake) I took note of the amount of light at that time and removed 10% of the lumen value.
Then, I created a rule (mind you, I use node red), where when the light sensor value is above x (light value - 10%) it closes the blinds to 50%.

Why mistakes?

  1. Because with the sensor behind the window, when the blinds are closed the sensor will never again get light on it. It’s stupid and I need to find a way to put it outside. Eventually.
  2. because it’s not only necessarily the amount of light that becomes uncomfortable. It’s also the shine. So it took me quite a bit to figure out why sometimes the lumens are nowhere near the level of the previous day, but wife is getting pissed.

So my suggestion would be, grab a xiaomi light sensor (they are zigbee) or make a light sensor with an esp8266 and tasmota. Place the sensor wherever it will stay and record a couple of days of data and map values to the amount of blind you want down.
Then you create the rule!

If lumens < 7000 then blinds to 30%
If lumens < 9000 then blinds to 50%

Etc. keep in mind that direct sun results in hugely higher lumen values than indoor lighting. I highly suggest you play around in the sun for this.
Hope this helps!

Of course! This one (Homematic HM-Sec-MDIR3) works well with Velux based on openHAB with appropriate bindings.

And, at least theoretically, with Hue Motion Sensor as well which provides an adjsutable daylight (on/off) value.