How Do Solar Panels Work? A Simple Guide

The Basics: Sunlight Becomes Electricity

Solar panels work through a process called the photovoltaic (PV) effect. When sunlight hits the silicon cells inside each panel, it knocks electrons loose, creating a flow of electricity. This is direct current (DC) electricity — the same type stored in batteries.

Your home uses alternating current (AC) electricity, so a device called an inverter converts the DC output from your panels into usable AC power. This happens automatically, instantly, and continuously while your panels are generating.

The Key Components of a Solar System

Solar Panels

Most residential panels contain 60 or 72 monocrystalline silicon cells. Modern panels from brands like JA Solar and Trina Solar achieve efficiencies of 20–22%, meaning they convert roughly a fifth of all sunlight hitting them into electricity. A typical 4kW system — the most popular choice for a 3-bedroom home — requires 10–12 panels.

The Inverter

The inverter is the brain of your solar system. It converts DC electricity from panels into AC for your home, monitors performance, and communicates with your smart meter. SolarEdge and GivEnergy make the most popular models for UK homes.

Generation Meter

A generation meter records how much electricity your panels produce. This data is used for Smart Export Guarantee (SEG) payments — the scheme that pays you for surplus energy you export to the grid.

Battery Storage (Optional)

Without a battery, surplus electricity is exported to the grid. Add a battery and that surplus is stored instead, ready for use in the evenings or overnight. Most households only self-consume around 30% of their solar generation without a battery — adding storage typically pushes this above 80%.

When Do Panels Generate Most?

Peak generation occurs on sunny summer days between 10am and 3pm. However, panels generate electricity in all daylight conditions — including on cloudy days. The UK averages around 1,100–1,400 kWh of solar irradiance per square metre per year, which is more than enough to make solar financially worthwhile.

A typical south-facing 4kW system in the Midlands generates approximately 3,400–3,800 kWh per year — enough to cover most of a household's electricity needs during daylight hours.

What Happens to Surplus Energy?

During peak generation (sunny afternoons), your panels often produce more than your home needs. This surplus follows one of two paths:

• Without battery: Surplus is automatically exported to the National Grid. With a SEG tariff, you're paid 4–15p per kWh exported.
• With battery: Surplus charges your battery first. Only once the battery is full does energy export to the grid.

Does My Roof Need to Face South?

South-facing roofs generate maximum output, but east, west, and even north-facing roofs can host productive solar systems. East-west splits are increasingly popular for commercial properties as they generate more evenly across the day. Our surveyors use specialist software to model your specific roof's generation potential before recommending a system.

Key Takeaways

• Solar panels convert sunlight to DC electricity via the photovoltaic effect
• An inverter converts DC to AC for home use
• A 4kW system generates roughly 3,400–3,800 kWh/year in the Midlands
• Surplus electricity is exported or stored in a battery
• Panels work in all daylight conditions, not just bright sunshine