Our Mitsubishi heat pump water heater has integration with some solar systems and weather services to attempt to time hot water production to solar peak.

We don't have solar panels but have a solar energy plan (cheap during the day, expensive during dawn/sundown, average overnight with fixed hourly schedule independent of actual production) so for us it's just programmed to follow a fixed schedule of prioritizing filling up during the solar hours and 100% forbidden from filling up during the expensive "duck curve" hours.