Solar panels convert sunlight into direct current electricity using photovoltaic cells
Solar panels generate electricity through a process called the photovoltaic effect. Photovoltaic (PV) cells are made from semiconductor materials, usually silicon, which absorb particles of sunlight called photons. When photons hit the cell, they knock electrons loose from their atoms, creating a flow of direct current (DC) electricity.
Solar panels convert sunlight into DC electricity via photovoltaic cells. A typical 3.5 kWp UK system generates 2,800–3,000 kWh yearly. An inverter changes DC to AC for home use, and surplus is exported to the grid under the Smart Export Guarantee.
- Photovoltaic cells absorb photons to create DC electricity.
- A 3.5 kWp UK system generates 2,800–3,000 kWh yearly.
- An inverter converts DC to 230V AC household power.
- Your home uses solar power first, then exports surplus.
- Export surplus earns payments under the Smart Export Guarantee.
- Solar panels convert sunlight into direct current electricity using photovoltaic cells
- An inverter converts the DC electricity into alternating current so your home can use it
- Your home uses the AC electricity first, then exports any surplus to the grid
- Quick numbers typical costs, savings, and payback for a UK home in 2026
- How solar panels actually save you money every month
- The Smart Export Guarantee pays you for electricity you send to the grid
- You must use an MCS-certified installer to qualify for SEG and government schemes
- How solar panels work on cloudy days and in winter
The amount of electricity a panel generates depends on the intensity of sunlight and the efficiency of the cells. Typical household panels have an efficiency of 15–22%. A standard 3.5 kWp (kilowatt-peak) system in the UK can generate around 2,800–3,000 kWh per year, according to the Energy Saving Trust (Energy Saving Trust, 2026).
An inverter converts the DC electricity into alternating current so your home can use it
Household appliances and the UK grid operate on alternating current (AC), not DC. The inverter, usually installed in the loft or near the meter, transforms the DC output from the panels into usable 230V AC electricity. Without an inverter, the electricity from your solar panels would be incompatible with your home wiring.
Micro-inverters can be fitted to each panel for better performance in partial shade, but they cost more than a single string inverter. The Microgeneration Certification Scheme (MCS) sets installation standards for inverters and panels (MCS, 2026).
Your home uses the AC electricity first, then exports any surplus to the grid
During daylight hours, the inverter feeds AC power directly to your home’s consumer unit (fuse box). Appliances and lights use this solar-generated power before drawing from the grid, reducing your electricity bill. Any electricity not used is automatically exported to the National Grid.
You can earn payments for exported electricity under the Smart Export Guarantee (SEG). Ofgem requires larger energy suppliers to pay you for every kWh you export (Ofgem, 2026).
Quick numbers typical costs, savings, and payback for a UK home in 2026
| Metric | Value | Source |
|---|---|---|
| Average system size | 3.5 kWp | Energy Saving Trust |
| Typical installed cost | £6,000–£8,000 | Energy Saving Trust (2026) |
| Annual electricity generated | ~2,800 kWh | Energy Saving Trust |
| Annual bill savings | £500–£700 | Energy Saving Trust |
| SEG export income (typical) | £80–£150 | Ofgem tariff data |
| Total annual benefit | £580–£850 | Calculated from EST figures |
| Payback period | 10–15 years | Energy Saving Trust (2026) |
How solar panels actually save you money every month
You use the free solar electricity first, reducing the amount you buy from your supplier at current unit rates. The more of your generation you use on-site, the greater your savings. Typical self-consumption is 30–50% without a battery.
Adding a battery can increase self-consumption to 60–80%, but adds £2,000–£5,000 to the upfront cost (Energy Saving Trust, 2026). The payback period for a battery alone depends on how much extra solar electricity you use and the battery’s lifespan, which is typically 10–15 years.
solar battery storage cost and savings guide
The Smart Export Guarantee pays you for electricity you send to the grid
The SEG requires larger energy suppliers to pay you for every kWh of electricity you export. You must have an MCS-certified installation to qualify for SEG payments. Export rates vary by supplier. In 2026, typical rates range from 3p to 15p per kWh, depending on the tariff (Ofgem, 2026).
To maximise your SEG income, compare tariffs from different suppliers. Some offer fixed rates, others offer variable rates linked to wholesale electricity prices. The average UK home exports about 50% of its solar generation.
You must use an MCS-certified installer to qualify for SEG and government schemes
The Microgeneration Certification Scheme ensures your installation meets industry standards for quality and safety. Only systems installed by MCS-certified companies are eligible for SEG payments and any future government grants. The Boiler Upgrade Scheme does not cover solar panels, but local council schemes may offer support.
You can verify an installer on the MCS website and check TrustMark for consumer protection (GOV.UK, 2026). Always ask for an MCS certificate before paying a deposit.
how to choose a solar panel installer
How solar panels work on cloudy days and in winter
Solar panels still generate electricity from diffuse sunlight on overcast days, though output drops to 10–25% of peak summer levels. In winter, shorter daylight hours and lower sun angle mean generation can be 80–90% lower than in summer, but it is never zero.
A 3.5 kWp system in the UK can still produce 100–200 kWh in a typical December, according to Energy Saving Trust data (Energy Saving Trust, 2026). This is enough to power lights, a fridge, and other low-energy appliances for much of the day. Panels are also more efficient in cooler temperatures, so they perform better on a cold sunny day than a hot one.
Frequently Asked Questions
Solar panels use the photovoltaic effect: photons from sunlight knock electrons loose in silicon cells, creating a flow of DC electricity. The Energy Saving Trust states a 3.5 kWp system in the UK produces around 2,800–3,000 kWh per year.
An inverter converts the DC electricity from solar panels into 230V AC electricity that your home appliances and the UK grid can use. The Microgeneration Certification Scheme (MCS) sets installation standards for inverters.
Yes, after the inverter converts it to AC, the electricity powers your home first before drawing from the grid. Any surplus is automatically exported to the National Grid, and you can earn payments under the Smart Export Guarantee (Ofgem, 2026).
A typical 3.5 kWp system in the UK generates 2,800–3,000 kWh per year, according to the Energy Saving Trust. Actual output depends on panel efficiency (15–22%) and sunlight intensity.
The Smart Export Guarantee (SEG) requires larger UK energy suppliers to pay you for every kWh of surplus solar electricity you export to the grid. Ofgem oversees the scheme, and rates vary by supplier.
Yes, solar panels still generate electricity on cloudy days because they use diffuse sunlight, though output drops. Micro-inverters can improve performance in partial shade, but they cost more than string inverters.
