Short answer: solar panels can be worthwhile when your roof is reasonably unshaded, you expect to remain in the property for several years, and the quotation is based on realistic generation and electricity-use assumptions.

What makes solar worthwhile?

Solar saves money in two ways: you buy less electricity from the grid and you may be paid for surplus electricity exported under a Smart Export Guarantee tariff. The value depends more on your home and usage pattern than on a salesperson’s headline percentage.

• Roof: an unshaded south-facing roof is ideal, but east- and west-facing roofs can still work well.
• Daytime use: savings improve when you can use washing machines, dishwashers, EV charging or other loads while the panels are generating.
• Time in the home: the longer you remain, the more likely you are to recover the upfront cost.
• System price: compare at least three like-for-like quotations.
• Export tariff: rates vary, so check current terms rather than relying on an installer’s assumed rate.

Typical UK figures

Energy Saving Trust’s April 2026 guidance puts a typical 3.5 kWp domestic system at about £6,100. Its July 2026 calculations suggest typical payback periods of roughly 9 years in London, 10–11 years in Manchester and 11–12 years in Stirling, depending on household usage. These are illustrations, not promises.

When solar may be a poor fit

• Heavy or unavoidable shading substantially reduces useful generation.
• The roof needs replacement soon, making later removal and refitting likely.
• The proposal is oversized for your usage and offers a weak export rate.
• The financial case depends on unrealistic energy-price inflation.
• You may move before the likely payback period and have not considered resale.

Questions to ask before signing

1. What annual generation is predicted, and what shading allowance has been used?
2. What percentage of generation am I expected to use at home?
3. Which electricity and export rates are used in the calculation?
4. Are scaffolding, grid application, monitoring and warranties included?
5. Is the installer MCS certified and covered by an approved consumer code?

Frequently asked questions

Do panels work in cloudy weather?

Yes. They generate from daylight, although output is lower than in strong direct sunlight.

Do I need a battery?

No. A battery can increase self-use, but its extra cost, efficiency losses and shorter lifespan must be tested separately.

Independent sources

Energy Saving Trust: solar panels · Ofgem: Smart Export Guarantee