This spring before launching swimming pool I decided to build an automated sun water heater which should heat the water during the sunny days.
Goal: manage water flow through sun collector when high level of sun intensity
I chose Sonoff TH10 device with temperature sensor for liquids and implant it into pipe. To pipe installed electric valve which open/closes water flow through sun collector.
Created server rule which turn on/off electric valve based on sun intensity, air temperature and water temperature.