When we moved in 2018 I put up a second solar PV array. It cost fr less than the original but the feed in tarrif or gov support was far lower.
Where you save is on buying in kWhs.
My system on average generates 11.08 kwh per day. More on average than we consume but of course in winter we import in summer we export. But the saved income wihout FIT is £1.11 per day at today's cost of electricity. With the FIT that rises ot £1.92
That array cost £ 5300 so the non FIT payback is 13.1 years & with the FIT 7.6 years.
However I do have a switch that diverts exported power to heat hot water & that saves gas so say another £50 pa.
At the end of 2022 I installed 4.2kWh of batteries as the payback improved driven by sales cost for power going from 16 to 26p / kWh.
That has cost £3276 and saved over 2019 kWh or £627 in 567 days. So a payback of 8 years.
I have just moved to Octopus Flux which has 3 time slots for tarrifs both of supply & export. I now will load the batteries from 02 - 05:00 hrs so that we maximise exportduring the day & hopefully at peak cost in the evening i.e. load shifitng. That should bring another £100 or so savings.
I would say you should easily get below 10 years as a payback and as energy costs increase that payback will reduce.
