We’ve got a solar thermal for our water too. Switched the hot water off about two months ago and haven’t had it on at all. Basically only using gas for the hob.I would get a battery, what is capacity of solar pv? You get next to nothing exporting to grid and will be months before you get paid anything. We now heat water by solar, past 3 months my gas is basically standing charge only and electricity from grid about 0.5 kWh a day.
Also got my FIT payment for May to July today: £586.