About Solar Reckoner

Solar Reckoner is an independent calculator for people in Great Britain weighing up a plug-in solar kit. It aims to give a straight, checkable answer for one home, not a national average.

How it's funded

The calculator is free. Some links to kits may be affiliate links: if you buy through one, the seller pays us a commission at no cost to you. Every such link is labelled "Affiliate link". Kits are ranked only by how fast they pay back for the home you describe, and a seller that pays nothing ranks exactly as it would otherwise.

How kits get listed

Every plug-in kit must be listed as compliant on ENA's device register (Connect Direct, formerly the Type Test Register) before it goes on sale, and a kit appears here only if its seller prints that register reference. Prices are read on the seller's own site and dated, and we never restate a price we haven't re-read. We give a payback only when a kit's price includes a mount for where your panels would go.

Where the numbers come from

Sunshine and the panel model come from the EU's PVGIS tool, and household use from the University of Edinburgh's IDEAL study of 255 UK homes. Prices come from Ofgem. The method page sets out every formula and source, with our checks against PVGIS.

Not advice

The results are estimates for a typical year. They are not financial or electrical advice. Before buying, ask the seller for the kit's ENA reference and check that your socket, wiring and building allow it.