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. should be also my friend.

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

thanks for any suggestion


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.