Solar Panel Payback Calculator
Estimate what a solar installation saves each year from self-used and exported electricity, when it breaks even, and its value over twenty years.
💼 Are you a real estate agent or broker? Send this calculator to your buyers on your own branded listing page — every enquiry comes straight to your WhatsApp. Create free agent page →Solar economics turn on one number that installers rarely lead with: how much of the generation you use yourself. Electricity you consume avoids the full retail price, while electricity exported earns a much lower rate — often a quarter of it. A system with high self-consumption pays back in half the time of an identical one on an empty house.
The other thing to get right is degradation. Panels lose output slowly but steadily, so a twenty-year projection at year-one output overstates the return by several percent.
The calculation
Annual benefit = (generation × self-use share × your electricity price) + (the rest × export price). That benefit is then reduced by the degradation rate each year and accumulated until it covers the installed cost.
Worked example
A 5,000 system generating 4,500 kWh a year with 50% self-use: 2,250 kWh avoided at 0.28 is 630, and 2,250 kWh exported at 0.08 is 180 — a benefit of 810 in year one, a 16.2% return on the cost. With 0.5% annual degradation it breaks even during year seven and is worth about 15,450 over twenty years.
Self-consumption is the lever
Raising self-use from 50% to 70% on this system lifts the annual benefit from 810 to 990 — a 22% improvement with no extra panels. Running the dishwasher, washing machine and any heating or vehicle charging during daylight is free; a battery does the same thing at a cost that has to be justified on its own.
Turn a calculation into an enquiry
Buyers who run these numbers are ready to talk. Give every listing its own page with your photo, phone and WhatsApp on it — leads land straight on your phone.
Create your free property pageFrequently asked questions
How much of my generation will I actually use?
Typically 30 to 50 percent without a battery, and higher for a household at home during the day or with an electric vehicle charged in daylight. It is the single most important input, so estimate it from your own routine rather than a brochure.
Is a battery worth adding?
It raises self-consumption substantially but is a large extra cost with a shorter life than the panels. Run the panels alone first, measure your real self-use, then evaluate a battery as a separate decision with its own payback.
Do panels really degrade?
Yes, typically 0.3 to 0.7 percent a year, and most manufacturers warrant around 80 to 85 percent of original output at twenty-five years. It is gradual, but ignoring it overstates a twenty-year projection by several percent.