Definition & identification

How do solar panels work?

From sunlight to your sockets — and how surplus power turns into income.

The short answer

Solar panels convert daylight into direct current (DC) electricity; an inverter turns that into the alternating current (AC) your home uses. Your home uses that power first; any surplus either charges a battery for later or is exported to the grid, where the Smart Export Guarantee (SEG) pays you for each unit. Panels generate whenever there's daylight — not only in direct sun — though output is highest on bright days.

Understanding the flow — generate, self-use, store, export — is the key to understanding both the savings and the income side of solar.

The components

Generate, use, store, export

  1. Generate: panels produce DC electricity in daylight.
  2. Convert: the inverter makes it usable AC.
  3. Self-use: your home draws from solar first, cutting imported power.
  4. Store: a battery (if fitted) banks surplus for the evening.
  5. Export: anything left flows to the grid and is paid via SEG.

What the Smart Export Guarantee is

The SEG obliges larger energy suppliers to pay you for surplus solar power you export. Rates vary by supplier and tariff, so the export side of your return depends on which SEG tariff you're on. To register for SEG, your system normally needs to be installed and certified by an MCS-certified installer.

Why MCS matters: an MCS certificate isn't just a quality mark — it's normally required to register for the Smart Export Guarantee, so a non-MCS install can cut you off from the export income entirely.

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Frequently asked questions

Do solar panels work on cloudy days?

Yes — they generate from daylight, not only direct sun, though output is lower on dull days and highest on bright ones.

What is the Smart Export Guarantee?

The SEG is a scheme under which larger energy suppliers pay you for surplus solar power you export to the grid. Rates vary by supplier and tariff.

Do I need a battery for solar to work?

No. Solar works without a battery — surplus is simply exported. A battery lets you store daytime generation for evening use, increasing self-use at extra cost.

Sources & further reading

Figures on this page are typical UK ranges drawn from published sources and depend on your specific home. They are guidance, not a quotation or guaranteed saving.