@Narwhalsh excuse me butting in, I’ve just had solar panels and a battery installed so thought you might be interested in my setup too.
12x325W panels = 3.9kwP with optimisers fitted (because shading)
3.6kW hybrid inverter
5.2kWh battery, 90% usable.
When fully charged it will run the house for at least 8 hours, usually more - up to 16 I think. Depends on temperature, as we have loft-mounted PIV units which suck electricity when the temperature is below 10 degrees (daily usage can be as much as double when it’s freezing). You would need to look at your house’s typical usage to work out what size of battery would be best for you (£ permitting - batteries are expensive). I wish I’d got the next size up (8.2kWh), but when I specified the system it wasn’t yet cold enough for the PIV things to kick in so I didn’t know about that - first year in this house.
I charge the battery at night on the cheap rate I have 00:30-04:30 (Octopus Go, as have an EV.). The past few days, the battery has been topped up from solar during the day enough that it had not run out by the time 00:30 came round again. In January (shorter days, colder, more cloud) it ran out at some point in the afternoon/evening.
As days get longer I will be able to reduce the overnight charge (not sure how soon/quickly). But I expect May-August we will be running almost entirely from solar and saved solar, plus will have some spare to put in the car. There is always some breakthrough grid draw, though, because the battery can’t supply more than 2.6kW and there is always some switching delay.
System cost £8,140. Looks like our winter bill will be little more than half what it was pre install, and summer bill should be not much more than the standing charge. A good chunk of the winter saving though is because of the split rate EV tariff, which you wouldn’t qualify for without an EV. Economy 7 would be worth looking at.