Solar panels explained How do solar panels work?
Daylight hitting the silicon cells in a panel knocks electrons loose, creating a direct current. An inverter turns that into the alternating current your home uses. Your house takes what it needs first, and the rest goes to the grid. Here's the whole path, step by step.
From daylight to your sockets
- Daylight reaches the cells. Each panel is made of silicon cells. Light energises them and produces direct current (DC) electricity. They work on cloudy days too, just less.
- Cables carry DC to the inverter. Panels are wired together and cabled through the roof to the inverter, usually in the loft or near your fuse board.
- The inverter converts it. It turns DC into the alternating current (AC) your home runs on, at the right voltage and frequency.
- A generation meter records it. It counts every unit the panels produce, which you can read without tools or ladders.
- Your fuse board shares it out. Electricity always goes to whatever's running in the house first.
- Spare electricity is exported. Anything you're not using flows out to the grid through your meter, which records it. With a battery, it charges first.
What solar panels are made of
| Part | What it does |
|---|---|
| Silicon cells | Turn light into electricity. Nearly all home panels use monocrystalline silicon. |
| Glass front | Protects the cells and lets light through. |
| Aluminium frame | Gives strength and lets the panel be clamped to rails. |
| Backsheet or rear glass | Seals the back. Some panels use glass on both sides. |
| Junction box and cables | On the back, connecting the panel to the next one. |
A typical 2026 home panel is about 1.76 m by 1.13 m, weighs around 21 kg and produces 450 to 485 watts in test conditions.
The rest of the system
- Mounting rails and roof hooks fix the panels above your tiles, attached to the rafters.
- Inverter: a single "string" inverter for the whole system, or microinverters or optimisers on each panel if the roof is shaded or split. See optimisers and microinverters.
- Isolator switches let the system be safely switched off.
- Generation meter and app show what you're producing.
- Export meter: usually your smart meter, which records exports so you can be paid for them.
- Battery, if you have one, stores spare power for later.
Why panels switch off in a power cut
Grid-connected systems must include "loss of mains" protection. When the grid goes down, the inverter shuts off within moments, so your panels can't send electricity into cables that engineers think are dead. So a standard system doesn't power your home in a power cut, even on a sunny day.
Some battery systems can keep chosen circuits running in a power cut, with the right equipment and setup. If that matters to you, ask at your consultation.
How much electricity they make
Each kilowatt peak of panels made about 805 to 970 kWh a year across the UK in 2024 and 2025, according to government figures; 2024 was a dull year and 2025 a sunny one. A typical 4 kWp home system makes roughly 3,200 to 3,900 kWh a year, more than a typical household's yearly use of 2,500 kWh, though much of it comes in summer and at midday.
Questions people ask
How do solar panels work on a house?
The panels turn daylight into DC electricity, an inverter converts it to AC, and your fuse board sends it to whatever's running. Spare electricity goes to a battery if you have one, then to the grid.
Do solar panels work without sun?
They work on daylight, including cloudy days, but not at night. Output drops in dull weather and winter.
Why don't solar panels work in a power cut?
For safety. The inverter must switch off when the grid fails, so it can't feed cables engineers are working on. Some batteries can provide backup with extra equipment.
What are solar panels made of?
Mostly silicon cells under glass, in an aluminium frame, with a sealed back and a junction box.
Do I use my solar power first?
Yes. Your home always uses the panels' power first; only the surplus is exported.
Read next
Sources
Figures and rules on this page were checked on 11 October 2026. Schemes, tariffs and prices change, so check the latest before you decide.
- Energy Saving Trust: Solar panels, costs, savings and benefits, updated 1 October 2026
- Energy Saving Trust: Solar power fact check, updated 13 August 2026
- MCS: MIS 3002 Solar PV installation standard, issue 1.0, January 2025
- Energy Networks Association: G98 single premises summary guide, checked 11 October 2026
- Trina Solar: Vertex S+ NEG9R.28 datasheet, 2026
- AIKO: Neostar 2P54 datasheet, checked 11 October 2026
- DESNZ: Digest of UK Energy Statistics 2026, chapter 6 (renewables), 2026
- Ofgem: Review of typical domestic consumption values, decision, 27 May 2026
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