Estimate your payback period, annual savings, and 25-year ROI before getting a quote.
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This gives a solid ballpark estimate. Real quotes vary by roof orientation, shading, panel brand, and installer pricing. Use this to understand the range before getting 2–3 real quotes.
A typical UK home uses ~3,500 kWh/year and needs a 3–4 kW system. A US home uses ~10,500 kWh/year and typically needs 6–10 kW. Divide your annual usage by (sun hours × 365) to get your target system size.
Most panels come with a 25-year performance warranty and last 30+ years. Output degrades ~0.5% per year. Our model assumes constant output for simplicity.
In the UK, the Smart Export Guarantee (SEG) pays you for exported electricity. In the US, the federal ITC gives a 30% tax credit on the full installed cost through 2032. In Australia, Small-scale Technology Certificates (STCs) give upfront discounts.
Yes — adding a battery (typically £3,000–£10,000 / $5,000–$15,000) extends payback by 2–4 years but increases self-consumption and protects against outages. Re-run the calculator with the battery cost added to get a combined ROI.
The Solar Panel Savings Calculator estimates how much money a solar panel installation could save you over time, how quickly the system pays for itself, and what your return on investment looks like over a 25-year system lifetime. Enter your system size in kilowatts (kW), the installation cost, your electricity tariff rate, your estimated annual energy consumption, and how much self-generated electricity you expect to use on-site (self-consumption rate). The calculator then works out your annual savings, payback period in years, and cumulative savings across the system's lifetime — giving you the key figures you need to decide whether solar is worthwhile before committing to installation quotes.
Solar panel economics depend on several interrelated factors. The most important are system size, local sunlight hours, self-consumption rate, and electricity price. A typical UK home might install a 3–4 kWp system that generates 2,700–3,600 kWh per year. If your household uses most of that electricity directly (a high self-consumption rate, achievable by running appliances during daylight hours or adding battery storage), you reduce the amount of expensive grid electricity you buy. Any surplus electricity you export to the grid earns export payments under the Smart Export Guarantee (SEG) in the UK. The calculator accounts for all of these income streams to give you an accurate net savings figure.
Over a 25-year period — the standard warranty duration for quality solar panels — a well-sized system on a UK home can save between £10,000 and £25,000 depending on system size, energy prices, and usage patterns. While electricity prices fluctuate, the long-term trend has been upward, meaning the financial case for solar tends to improve over time. The calculator lets you run scenario analysis by adjusting the electricity price to see how savings change if energy costs rise or fall. This sensitivity analysis is valuable when assessing the risk and reward of the investment before getting firm quotes from installers.
The typical payback period for a UK solar installation is 8–14 years, depending on system size, your electricity tariff, how much of the generated power you use directly, and whether you add battery storage. Systems installed at current (2024–25) electricity prices often pay back faster than installations from five years ago because unit rates have risen significantly.
The Smart Export Guarantee is a UK government scheme that requires electricity suppliers with over 150,000 customers to offer a tariff for electricity you export to the grid. Rates vary between suppliers, typically ranging from 4p to 15p per kWh exported. The calculator can include export income once you know the rate you would be offered.
Self-consumption is the percentage of your solar generation that you use directly rather than export. Without battery storage, a typical household achieves 30–50% self-consumption. With a home battery, this can rise to 70–90%. Using appliances (dishwasher, washing machine, EV charging) during daylight hours also boosts self-consumption without any additional hardware.
Yes. Solar panels generate electricity from daylight, not direct sunshine. They still produce power on overcast days, though at reduced output — typically 10–25% of their peak capacity on heavily overcast days. UK systems are designed around average annual irradiation figures that account for the country's mixed weather.
Quality solar panels are typically warranted for 25 years, with most manufacturers guaranteeing at least 80% of original output at year 25. In practice, panels often continue generating electricity beyond 30 years, making them a durable long-term investment.