Estimate how long a solar installation takes to pay for itself, and what it earns over its lifetime.
What drives solar payback
The single biggest factor is how much of your own production you actually use. Electricity you consume yourself replaces power you would have bought at the full retail price, while surplus you export is usually paid at a much lower rate. Shifting laundry, dishwashing and car charging into daylight hours therefore shortens payback more than adding panels does.
Panels lose a little output each year, typically around 0.5%, and an inverter usually needs replacing once in a 25-year life. This estimate keeps production flat and ignores that replacement, so treat the payback figure as an optimistic baseline and confirm the numbers with a quote for your roof.