You’ve missed the boat on PV ,Teasel, the feed-in tarif dropped so much at the end of July I doubt you’ll see any new installations.
I’ve had PV for over 3 years and I’m on target for the system paying for itself in the predicted 6,5 years when a tax credit is included. The waterproofing kit leaked but has been replaced by the installer free of charge. Production is nearly double our consumption.
I’ve had solar thermal for 5 years and that’s on target for paying for itself in 11 years with no tax credits or subsidies. It thermo-syphons, has no moving parts and has required zero maintenance except cleaning the glass now and then.
Insulating our house and using more efficent appliances has reduced our energy consumption to a third of what it was. If you want to save the planet then insulate first and worry about energy production after.