I'm surprised that there isn't a least the option to divert the power to water heating before it goes back into the grid. Or maybe there is but people preferred the feed in tariff ?
A distinction needs to be made there between financial and technical.
Technically it's dead easy simply to run the controlled load (off-peak) supply at the required times.
Financially that gets consumers in a lather however since they're exporting their solar power through one meter and simultaneously buying it back through another meter, usually at a higher price.
For those who take an objective view and crunch the numbers, that's not necessarily a bad deal since it does away with any need to be "clever" about it on your part trying to outsmart the sun.
In my own case that's precisely what I'm doing. Hot water is on Off Peak Controlled Load (OPCL) and, since it needs a maximum of 4.5 hours to fully heat the tank, the 10am - 3pm window is just fine. I've disabled it via settings on the water heater but if more hot water was then I could also use the 1am - 6am supply period but in practice I've no need to do so.
Depending on retailer, you'll be paying 50 - 60% below the standard flat rate for power through that meter so whilst it's higher than most retailers will pay for exported solar, any loss on your part won't be much and it completely removes the need to mess about watching the sun or switching things on and off etc.
That I'm clocking up two meters simultaneously, the solar export and also the OPCL import, is not a problem technically. Just means I'm paying to use my own power - but for the sake of the ~$55 a year I'm losing (and that's assuming I managed to somehow get the timing perfectly right in using my own solar and never heated from the grid) it's just not worth stuffing about trying to be clever with that one.
For those who do want a clever workaround though, well Tasmania has Tariff 93 which just happens to conveniently apply the lowest price between 10am and 4pm (as well as 9pm - 7am). Everything goes on one meter and with a timer to run the hot water during the middle of the day you can't possibly lose - it'll take your own solar power first, and import from the grid at the cheapest price second. Can't lose.
For those in SA a similar option was introduced on 1 July 2020 via the network tariffs (what retailers pay to use the network) and your retailer should be offering this to you in the near future.
You'll need a Type 4 meter, aka Smart Meter, to go with that option in SA however and the cheapest time is 10am - 3pm with the second cheap period being 1am - 6am. That'll work just fine with solar however, same as in Tas, so you put the whole lot on the one meter, timer starts the hot water up at 10am, and by default you're using your own solar first, importing from the grid at a low price second.