Rooftop Solar Estimator
System Design & SizingFind your home on the satellite map, trace your roof, and see the solar system that fits — panels, size, generation and savings.
- 100% Free
- Instant Results
- Accurate & Reliable
- Data for Your Country
- Beginner
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About this calculator
Find your home on the satellite map, trace your roof, and see the solar system that fits — panels, size, generation and savings.
What this calculator does
The Rooftop Solar Estimator is a country-aware estimator set up for United Kingdom. Enter your own figures rather than typical ones — averages hide the variation that decides whether a system pays back.
Results are calculated against assumptions for United Kingdom, including local tariffs, sun hours, typical installed costs and any incentives in force. Switching country in the header re-runs the calculation on that market's data, which is why the same inputs can produce very different answers in two countries.
Getting an accurate result
- Use twelve months of electricity bills rather than one. Consumption swings seasonally, and a single winter or summer bill will bias the answer in one direction.
- Enter your actual tariff, including standing charges and any time-of-use rates — the value of a generated kilowatt-hour is what you avoid paying, and that is rarely the headline rate.
- Be honest about shade and roof orientation. A pitched roof facing away from the sun, or with a chimney over it for part of the day, can lose a fifth of its yield.
- Check what your utility pays for exported power before assuming surplus has value; in some markets it earns close to nothing.
- Re-run the calculation with a pessimistic set of inputs as well as a realistic one. If the case still holds at the pessimistic end, it is a robust one.
What this calculator cannot tell you
Estimates here are based only on the figures you enter and the country assumptions behind them. They do not account for the condition or age of your roof, structural or wind-load limits, the state of your consumer unit and earthing, permit and grid-approval timelines, scaffolding or access costs, or shading from anything a survey would pick up. Any of those can move the real number substantially.
Use the result to decide whether to get quotes and roughly what size to ask for. Treat an installer's surveyed quotation, not this page, as the figure to make a purchase decision on.
Rooftop Solar Estimator — FAQs
Is the Rooftop Solar Estimator free to use?
Yes. Every SolarBazaar calculator is free, needs no account, and returns results instantly. Your inputs are used to produce the estimate against United Kingdom's local assumptions.
How accurate is this calculator?
It is as accurate as the inputs you give it. With real consumption figures from twelve months of bills, your actual tariff and an honest assessment of roof orientation and shade, results are typically a good planning-grade estimate. It cannot account for roof condition, structural limits, grid-approval delays or access costs, so a surveyed installer quotation will always be closer.
Does the Rooftop Solar Estimator use local data for United Kingdom?
Yes — calculations run against country-specific assumptions covering tariffs, sun hours, typical system costs and incentives for United Kingdom. Switching country in the header re-runs the same inputs against that market's data.
What information do I need before I start?
Recent electricity bills, your current tariff, and a rough idea of your roof's usable area and orientation cover most calculators on the site.
What else is in the System Design & Sizing category?
System Design & Sizing calculators on SolarBazaar cover the related questions you will hit next — the full set is linked from the calculators directory, and results carry across because they all use the same country assumptions.
Accurate. Reliable. Country-Specific.
Our calculators use real local data including tariffs, sun hours, system costs and incentives.
Disclaimer: This calculator provides estimates based on the information you provide. Actual results may vary. Please consult a solar professional for a detailed assessment.