We had solar panels fitted a few weeks ago, as many as would fit on our roof & garage together (giving a nominal 10.1kWh system), and a 16kWh battery.
Since 10th February, we have already generated 442kWh - at the rates from 1st April, that would be £125 worth in less than a month, during the winter.
The total system cost us around £20,000 fully installed so that is a payback time of around 160 months, but we will obviously be generating quite a bit more during the summer, so 10 years seems a reasonable estimate - provided electricity prices don't rise much more.
The battery hasn't actually been installed yet - stock is arriving on 15th April, but when it is, we will be switching to the Octopus Agile tariff for both import and export, and I suspect the payback time will then be better, as we will be getting a good rate for what we export, not just saving on what we use.