Solar Savings Calculator
See how much you could save with solar panels on your Welsh property. Our calculator uses real generation data for Wales and current Ofgem electricity prices.
Enter your details below – takes 30 seconds and gives an indicative monthly, annual and 25-year saving figure.
Calculate your savings
How we calculate savings
Our calculator uses MCS-approved methodology and real generation data for Wales sourced from the European PVGIS database. We apply different offset factors based on roof orientation – a south-facing roof offsets around 80% of an average household's bill, falling to about 45% for a north-facing roof.
For commercial premises we apply a 5% generation premium to account for larger system sizes, optimum tilt and lack of shading.
The lifetime figure assumes 25 years of operation with a 0.4% annual panel degradation rate and a 3.5% annual electricity price inflation. These are conservative assumptions – actual savings are usually higher.
What the savings number does not include
Our calculator gives a deliberately conservative indicative figure based purely on offsetting your daytime electricity usage. The actual financial benefit of solar is usually significantly higher because:
- SEG income – you sell any unused electricity back to the grid at 5-15p per kWh under the Smart Export Guarantee
- Battery time-shifting – with a battery you can store cheap off-peak electricity and avoid expensive peak imports
- EV charging – charging your car from solar at near-zero marginal cost can save £1,500-£2,000 a year by itself
- Property value – Land Registry data suggests solar adds 4-14% to property value on a like-for-like basis
- Carbon savings – a 4kW system avoids roughly 1.2 tonnes of CO₂ per year, equivalent to taking a small car off the road
For a fully-modelled financial projection including all of the above, please book a free survey.
Frequently asked questions about solar savings
How accurate is your calculator?
Typically within ±10% of the real-world figure once a full survey has been completed. For a precise number we need to measure your roof, check for shading and confirm your annual consumption.
Why does roof orientation matter so much?
South-facing roofs receive the most direct sun during peak daytime hours. An east-west split is good because you generate over a longer day. A north-facing roof still generates – about 55-60% of south – but the maths is usually harder.
Does the calculator include battery storage?
Not directly. The calculator estimates savings from solar self-consumption. Adding a battery typically increases self-consumption from 35% to 80% and is reflected in the "daytime" usage option.
What is the typical payback period?
Most Welsh domestic systems pay for themselves within 6-9 years. Commercial systems typically pay back in 4-7 years thanks to higher daytime usage.
Should I include the cost of finance?
If you are paying cash, the simple payback calculation above is correct. If you are using 0% finance, savings start immediately. With paid finance, payback is extended by 1-2 years.
How the calculator works and what it does not show
The savings calculator on this page uses well-established irradiance figures for Wales, typical system efficiencies, and current electricity tariffs to produce a quick estimate. It is intended as a starting point for your decision, not a replacement for a proper site survey. The figures shown assume a reasonably unshaded roof of suitable orientation, standard installation, and no significant changes to your usage pattern over time.
What the calculator cannot account for is your specific situation: the exact shading on your roof from a neighbouring tree or chimney, the condition of your existing wiring, whether your meter cupboard has room for new equipment, and how your usage might change if you switch to an electric vehicle or heat pump. These factors can all materially improve or reduce the real-world performance of a system, which is why we always follow up with a free in-person or remote survey before issuing a formal quotation.
Understanding payback and lifetime savings
For most Welsh homes, a well-specified solar system pays back its installation cost within seven to ten years through a combination of reduced electricity bills and Smart Export Guarantee payments. Once paid back, every further unit of electricity generated is effectively free, and modern solar panels are warranted to deliver at least eighty percent of their original output after twenty-five years.
Adding a battery typically extends the payback period by a couple of years but significantly increases self-consumption, meaning you use more of what you generate rather than exporting it cheaply. For households with high evening usage, electric vehicles, or time-of-use tariffs, batteries often make excellent financial sense in addition to providing resilience during power cuts.
What to do once you have your estimate
If the numbers look promising, the best next step is to book a free survey. We will spend around an hour at your property looking at the roof, taking measurements, checking your consumer unit, and discussing your goals. You will receive a tailored proposal within a few working days with firm pricing and a detailed performance estimate, and there is no obligation to proceed.