Last reviewed: June 2026 | Source: Ofgem and the Microgeneration Certification Scheme
TL;DR- A typical 4 kilowatt-peak solar system in the UK generates roughly 3,400 to 4,200 kilowatt-hours a year.
- South-facing roofs at a pitch of around 30 to 35 degrees give the best output.
- Shading, dirt and high temperatures all reduce panel performance.
- The Smart Export Guarantee pays households for electricity they export to the grid.
- MCS certification of the installation is usually required to access export payments.
Key Facts
●Typical system size: Around 4 kilowatts-peak (kWp) for a home
●Typical annual output: Roughly 3,400 to 4,200 kWh per year
●Best orientation: South-facing
●Optimal pitch: Around 30 to 35 degrees
●Export scheme: Smart Export Guarantee (SEG)
●Certification: Microgeneration Certification Scheme (MCS)
Solar panels have become a common sight on UK roofs, but how much electricity they actually generate, and what a household can earn from exporting surplus power, depends on several factors. With the older Feed-in Tariff closed to new applicants, the Smart Export Guarantee is now the main route to payment for exported electricity. This guide explains typical output, what affects performance, how the Smart Export Guarantee works, the role of MCS certification and the typical payback period.
How much electricity solar panels generate
A typical domestic solar system of around 4 kilowatts-peak generates roughly 3,400 to 4,200 kilowatt-hours of electricity a year in the UK, depending on location and conditions. The kilowatt-peak figure describes the system's capacity under standard test conditions, while the annual output reflects real-world performance over a year.
Output is higher in the south of the UK and in summer, when days are longer and the sun is stronger, and lower in winter and in the north. Even so, panels generate electricity across the year, not just in summer, because they respond to daylight rather than only direct sun.
The amount a household actually benefits from depends not only on total generation but on how much of it is used in the home rather than exported. Using electricity while the panels are generating, for example by running appliances during the day, increases the value of the system.
What affects panel performance
Orientation and pitch are among the most important factors: a south-facing roof at a pitch of around 30 to 35 degrees gives the best output in the UK, while east or west-facing roofs generate less, and north-facing roofs are generally unsuitable. The angle and direction determine how much sunlight the panels capture across the day and year.
Shading from trees, chimneys or neighbouring buildings reduces output, sometimes significantly, because even partial shade on some panel types can cut generation. Dirt, leaves and bird droppings, known as soiling, also reduce performance, so occasional cleaning can help, though rain removes much of it naturally.
Temperature has a counter-intuitive effect: very hot panels are slightly less efficient than cooler ones, so the highest output is not necessarily on the hottest day but on a bright, cooler day. Panel quality and the age of the system also matter, as output declines gradually over many years.
The Smart Export Guarantee
The Smart Export Guarantee, or SEG, requires larger electricity suppliers to offer payments to households that generate their own electricity and export the surplus to the grid. It replaced the older Feed-in Tariff for new installations, and the rate paid for exported electricity is set by each supplier rather than fixed by government.
Because suppliers set their own SEG rates, the amount paid per exported kilowatt-hour varies between them, and households can choose an SEG tariff that suits them. A smart meter or other suitable metering is usually needed to measure the electricity actually exported, so payments reflect real export.
The SEG pays only for electricity exported to the grid, not for electricity generated and used in the home. This is why maximising self-consumption, by using power while the panels generate, is valuable: it avoids buying electricity at the higher import rate, while export earns the lower SEG rate.
MCS certification
The Microgeneration Certification Scheme, or MCS, certifies small-scale renewable installations and the businesses that install them. An MCS-certified installation is generally required to access the Smart Export Guarantee, so certification matters for households that want to be paid for exported electricity.
MCS certification provides assurance that the installation meets recognised standards and that the installer is accredited. Using an MCS-certified installer is therefore important both for quality and for eligibility for export payments, and homeowners should check certification before commissioning an installation.
Beyond eligibility for the SEG, MCS certification can be relevant for warranties and for demonstrating the system's specification. Keeping the certification documents safe is sensible, as they may be needed when applying for export payments or if the property is later sold.
Typical payback periods
The payback period for a domestic solar system, the time taken for the savings and export income to cover the installation cost, is often estimated at around eight to twelve years, though this varies widely with the system cost, electricity prices, how much generation is used in the home and the export rate.
Higher electricity prices shorten the payback because the savings from self-generated electricity are worth more, while a high proportion of self-consumption also improves the return. Conversely, a household that exports most of its generation at a low SEG rate sees a longer payback.
Because panels typically continue generating for many years beyond the payback period, the system can produce savings well after it has paid for itself, though output declines slowly over time. The actual return depends on individual circumstances, so households should base estimates on their own usage, costs and quotes.
Getting the most from a solar system
Maximising self-consumption is the single most effective way to improve the value of a solar system, because using electricity while it is being generated avoids buying it at the higher import rate. Running appliances such as washing machines and dishwashers during daylight hours helps achieve this.
Some households add battery storage to store surplus generation for use in the evening, increasing self-consumption further, though batteries add cost and the economics depend on usage and prices. Whether a battery improves the overall return depends on the household's pattern of use.
Choosing a competitive Smart Export Guarantee tariff, keeping panels free of heavy soiling and ensuring the system is well maintained all help preserve performance. Comparing SEG rates between suppliers and reviewing usage patterns allows a household to make the most of what its panels generate.
Frequently Asked Questions
How much electricity does a typical UK solar system generate?
A typical domestic system of around 4 kilowatts-peak generates roughly 3,400 to 4,200 kilowatt-hours of electricity a year in the UK, depending on location and conditions, with higher output in the south and in summer. Panels generate across the year because they respond to daylight rather than only direct sun. How much a household benefits depends on how much of that generation is used in the home rather than exported.
What affects how much my solar panels produce?
Orientation and pitch are key: a south-facing roof at around 30 to 35 degrees gives the best output in the UK, while east or west-facing roofs generate less and north-facing roofs are generally unsuitable. Shading from trees or buildings reduces output, as does soiling from dirt and leaves, while very hot panels are slightly less efficient than cooler ones. Panel quality and the age of the system also affect performance.
What is the Smart Export Guarantee?
The Smart Export Guarantee, or SEG, requires larger electricity suppliers to offer payments to households that generate their own electricity and export the surplus to the grid. It replaced the older Feed-in Tariff for new installations, and each supplier sets its own export rate, so the amount paid per exported kilowatt-hour varies. A smart meter or other suitable metering is usually needed, and the SEG pays only for electricity exported, not for power used in the home.
How long do solar panels take to pay for themselves?
The payback period is often estimated at around eight to twelve years, but it varies widely with the system cost, electricity prices, how much generation is used in the home and the export rate. Higher electricity prices and a high proportion of self-consumption shorten the payback, while exporting most generation at a low rate lengthens it. Panels typically keep generating for many years beyond payback, though output declines slowly over time.
