Smart switch for hot water system power source and run time

1

I have a hot water system connected to controller load 1 off peak. It does not have an on-peak secondary element. One thing I am attempting to do is turn on as many loads when solar is producing and reduce load when solar production drops. This has been successful with low power devices like pumps via Sonoff Pows and smart control of AC.

Has anyone done anything with smart switches to:

  1. Run hot water off solar during the day if excess power is available.
  2. Run on controller load 1 during the night if not enough runtime was achieved during the day.

Definite purpose contactors are available as both transfer switching between feeds and also low voltage switching on/off.

Does anyone have experience with these devices for such a purpose and/or have any recommendations on a particular brand/model that has both dual feed and on/off switching (and one that would be legal to have installed into a DB). A small controller with a low voltage relay could then provide the control over feed selection and power with the smarts coming from OpenHab rule engine.

Or any other suggestions for this. Are their smart circuit breakers for residential DBs that could do this job?

Based on my current solar and off peak usage I could save up to 5kWh per day or 2000 kWh of usage per year not needing to come off the grid while also using cheap off peak if solar has a bad day. So one of the solar power diverters (https://www.solarquotes.com.au/blog/solar-hot-water-diverter-comparison/) don’t make too much sense as they have a multiyear cost to repay.

2

I have limited experience with residential power options regarding solar but figured I would chime in. I am going to assume this is in North America? If not, that may be a whole different kettle of fish.

There are all sorts of commercial contactors out there with both low and high voltage control that will handle loads in the 240v and 30 to 140 amps. They also have lots of versions with multiple circuits like primary and secondary all as part of the same module. With that said… none of that is cheap, let alone affordable. I am sure that this type of kit can be installed in residential applications but I am pretty certain, though don’t know for sure, that any inspector would like to see auxiliary solar control in its own enclosures. There are no “residential” smart breakers that I am aware of. Any of that kind of control hardware is considered “industrial” or “experimental, solar, etc” and is installed as auxiliary gear. The part where that sucks is the control side and that is due to the UL certs required for it to be part of the home wiring. Of course, if it isn’t being inspected… ya know. That comes with the usual disclaimer- if you install non-certified components or controllers, its your insurance not mine.