If you switch your hot water back to Peak Usage it will simply heat the water when it goes below its set temperature.
No guarantee that it will operate when solar is available.
To do this you would need to a timer switch installed to ensure that it will operate during daylight times.
You may have seen adverts for chromagen hotwater systems, We have a 170l system (the free one) which I have set the time to only run from 11:00 to 17:00 and this suits our needs (two users).
I would suggest that you look at the kilowatt usage of your hotwater service and compare that to the amount of power you put back to the grid. Remember if your hotwater uses more than the excess power you are putting back to the grid (especially winter time) you will be paying peak rates rather than the much cheaper off peak rates.
The cost of having the connection changed, a timer installed or adding a chromagen may outway any benefit you gain anyway.
Hope this gives you some thoughts on the subject.
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