I have searched the web for a Battery powered light sensors and didn’t find anything.
all I could find were some all-in-one sensor hubs that require constant power (e.g. Shelly Sense or Broadlink A1). is there any other option?
I know that there are DIY solutions, but I prefer not to deal with DIY.
I also know the xiaomi aqara motion sensor option, but I saw that it sends lux updates only when there is a movment detected, so it is not a good solution for me.
The more frequent you send the lux values, the shorter is battery life, though.
I get about one year of battery life with the settings above.
Sorry for late reply and welcome to the OpenHAB community! I use Hue motion sensor for light level because they are cheap ($30 usd) and respond in near real-time. Of course your will need Hue hub or zigbee dongle