I'm in Poland and every solar installation I've looked at has a pay back time of around 5 years. The main reason is subsidized electricity — consumer prices are artificially low. If you take commercial pricing, it's closer to 2-3 years.
India is clearly different to the West in this regard; a typical installation in the UK is much smaller than 10kW, more in the 3-5kWp range, and you're looking at £6000 installed without a battery, and over £10,000 with a battery (circa 10kWh).
A 10kWp installation with a battery will easily cost you £15,000-£20,000, with an annual energy bill of ~£2000 it's easy to hit 7-10 years ROI.
To put some numbers to my specific case, my 7kWp system with 12kWh battery was ~£13,000 in summer 2025, and about 55-60% of the cost came from scaffolding and labour.
