The main fly in the ointment is the shadow from one of my mature Ash trees. I planted 800 Ash, among over 2500 trees in my "wildlife area", but they almost all died of There is no way I'm felling a mature tree of any kind, especially Ash! This does mean I get reduced winter generation for a few hours when it's sunny.

Although I am G100 limited to 6.5kW export, the whole of the battery/charge controller system sits on the DC side of the installation (invisible to the grid). So, when it's sunny, I have seen 16kW going into the batteries. Meaning the 28kWh batteries could potentially be charged from empty in under 2 hours.

... the next year (2024) we installed heat pumps. Air to water would have been very tricky in our house, so we went with Air to Air, which many people (v.annoyingly) call "AirCon". Ours are Mitsubishi Electric. Bought 99% for heating, but means we get free cooling, should we need it, in the summer. There is no mains gas here but, over the years, we've used oil, smokeless coal, logs and wood pellets. With Octopus Intelligent Go and batteries we almost never pay over 7ppu for electric.

I would be very interested in people's opinions on green water heating solutions. Our air to air heat pumps don't provide hot water. In the summer we mostly get it from the roof Solar Thermal, but on cloudy days and winter we would need to use the electric immersion heater or the oil boiler. Has anyone used a dedicated hot water heat pump, with exterior heat exchanger panels? Our plumbing system is also very complicated, so may not be easy to integrate.

@ArborealTechie it’s not easy to even start to answer without knowing how your existing system works. Do you have a hot water tank and if so, how large is it? Is it well insulated? If there is no insulation on your hot water tank or there is no hot water tank then you are probably better with on demand hot water. If you have a high demand for hot water, it might be well worth getting renewables involved.
But if you have an electric shower your demand for hot water is probably minimal.

@peterbrown Thanks Peter. All good points. Like everything here the answer is complicated! We have an electric shower but it hasn't been used in years. We have a 200l heat store tank, with immersion heater and multiple internal heating coils. Water can be heated by electric, oil, coal (Rayburn with back boiler) and solar thermal. We use a shower with close to mains pressure from the heat store. If I get a "green" DHW solution I may need to sacrifice some of the existing flexibility.