Solar panels work by turning sunlight into electricity using special cells made of silicon, and a typical home system can generate around 2,650 kWh per year (Energy Saving Trust, 2026). This is enough to power a family home for months, and it’s clean energy that doesn’t harm the planet.
- Solar panels use silicon cells to convert sunlight into electricity.
- A typical home system generates around 2,650 kWh per year (Energy Saving Trust).
- An inverter changes DC electricity from panels into AC for your home.
The key idea is simple: sunlight hits the panel, and the panel makes electricity. But how does it actually happen? The answer depends on the materials inside the panel and the way they interact with light. This works for any home with a roof that gets direct sunlight, but it won’t work at night or on very cloudy days without battery storage.
Sunlight hits the silicon cells
Solar panels are made of many small cells, each containing two layers of silicon. When sunlight particles called photons hit the silicon, they knock electrons loose from their atoms (GOV.UK, 2026). The layers are treated so one layer has extra electrons and the other has fewer, creating an electric field. This field pushes the loose electrons to flow in one direction, generating a direct current (DC) of electricity. Think of it like a push that makes tiny particles move in a line.
The inverter turns DC into usable AC power
The electricity from the panels is direct current (DC), but your home needs alternating current (AC) to run lights, TVs, and fridges. A device called an inverter changes DC to AC (Energy Saving Trust, 2026). It’s like a translator that makes the electricity speak the right language for your house. Most inverters are about 97% efficient, so very little energy is lost in the conversion. The AC power then flows through your fuse box to power your appliances.
Extra electricity goes to the grid or a battery
On sunny days, your panels might make more power than you need. That extra electricity can be sent to the National Grid through a scheme called the Smart Export Guarantee, which pays you for it (Ofgem, 2026). Alternatively, you can store it in a home battery for use at night or when clouds block the sun. This makes solar panels a smart way to use free sunlight to power your home and even earn money.
A worked example
A typical 3.5 kWp solar panel system on a 1930s semi-detached house in Manchester costs around £7,000 after the 0% VAT saving (which runs until March 2027). This system generates roughly 2,650 kWh per year according to the Energy Saving Trust, saving a family about £640 annually on electricity bills at current average rates of 24.5p per kWh. With the Smart Export Guarantee (SEG) paying around 15p per kWh for surplus power exported to the grid, you could earn an extra £120 each year. The total yearly benefit of £760 means the system pays for itself in just over nine years. Over a 25-year lifespan (panels typically last 25–30 years), the total savings and SEG income reach roughly £19,000, making it one of the most reliable home energy upgrades available.
| Item | Figure |
|---|---|
| Upfront cost after grants | £7,000 |
| Yearly savings | £760 |
| Payback period | 9.2 years |
| 25-year lifetime savings | £19,000 |
What homeowners often get wrong
The most common mistake is thinking solar panels need direct scorching sunshine to work, when they actually generate electricity from daylight even on cloudy UK days. Here are three frequent errors that cost homeowners money or miss out on savings.
- Believing panels stop working in winter Many assume winter means zero generation, but a typical system still produces about 20–25% of its annual output from October to March. You will still cut your winter electricity bills by roughly £100–£150.
- Ignoring the Smart Export Guarantee (SEG) Some homeowners never bother signing up for SEG payments because they think it is not worth the effort. Missing this means losing £100–£200 per year in income from surplus electricity sent to the grid, which adds up to thousands over the system’s lifetime.
- Thinking batteries are essential from day one A common belief is that you must install a battery at the same time as panels, but this can add £4,000–£6,000 upfront. You can add a battery later when prices drop, and still benefit from the panels and SEG payments immediately.
Quick reference
- Solar panels generate electricity from daylight, not direct sunlight, so they work on cloudy UK days but produce less power.
- A 3.5 kWp system costs roughly £7,000 after 0% VAT and saves around £640 per year on electricity bills.
- The Smart Export Guarantee pays you for surplus power sent to the grid at rates around 15p per kWh.
- Panels typically last 25–30 years with minimal maintenance, requiring only occasional cleaning and an inverter replacement after 10–15 years.
- You do not need planning permission for most homes, but listed buildings or conservation areas require checking with your local council first.
Frequently Asked Questions
Solar panels work by using sunlight to knock electrons loose in silicon cells, creating electricity. A typical home system can generate around 2,650 kWh per year (Energy Saving Trust, 2026).
Solar panels are made of many small cells containing two layers of silicon. One layer has extra electrons and the other has fewer, creating an electric field (GOV.UK, 2026).
No, solar panels do not work at night because they need sunlight to generate electricity. Without battery storage, they also produce less power on very cloudy days.
