How much you save from plug-in solar depends on three things: where you live, which direction your panels face, and what you pay for electricity. Use the calculator below to get a personalised estimate, then read the notes underneath to understand what the numbers mean.
When you use electricity. Plug-in solar feeds power into your home as it generates. If nobody is home during the day, much of that generation flows unused to the grid with no payment. If you work from home or have high daytime usage, you will capture more of what the panels produce.
Shading. Trees, adjacent buildings or roof overhangs can significantly reduce output if they shade your panels for part of the day. The calculator assumes an unshaded position.
Panel quality. Higher efficiency panels generate more electricity per square metre. The calculator uses average monocrystalline panel figures. Premium IBC or HJT panels will perform slightly better, particularly in low-light conditions.
Battery storage. Adding battery storage lets you use solar-generated electricity in the evening rather than losing it to the grid. Pairing a battery with a time-of-use tariff such as Octopus Go can increase your annual saving significantly compared to a panel-only setup.
Understanding the payback period
The payback period is how long it takes for your cumulative electricity savings to equal the upfront cost of the kit. After that point, you are generating free electricity for the remaining life of the system, typically 20 to 25 years for the panels and 10 to 15 years for the microinverter.
A payback period of three to five years for a panel-only system is normal for a well-positioned UK installation. If the calculator shows a longer payback than this, check your panel orientation. An east-facing panel in the north of England is a very different financial proposition to a south-facing panel in the south.
Ready to buy?
If the numbers look worthwhile for your situation, our Best Kits of 2026 page covers the most popular UK systems with honest reviews and current pricing. If you have more questions, the FAQ covers the most common ones in plain English.