Last updated: 13 March 2025

Solar Panel Calculator UK: Calculate Costs, Savings & Output

Q: How do you calculate how many solar panels you need?

GreenMatch’s solar panel calculator estimates the number of panels needed by taking into account your annual energy consumption, available roof space, and the wattage of typical solar panels.

Q: How do you calculate the payback time of solar panels?

The solar panel payback time is calculated by dividing the total installation cost by the annual savings on your energy bill. We also factor in potential increases in electricity rates to provide a more accurate estimate.

Q: How do you calculate how much solar energy you will generate?

To estimate solar panel energy generation, consider the wattage of your solar panels and the average daily sunlight hours in your location. Multiply the panel wattage by the number of sunlight hours to get daily energy output in watt-hours.

Written by

Alejandro Staton Varela

Last updated

13 March 2025

Calculating solar panel costs, savings, and energy output can be a bit complex, considering several variables. That's why we've created our solar panel calculator, a user-friendly tool designed to help you quickly estimate what solar panel system is right for you, its cost, and how much you can save by installing solar panels on your home.

Just enter a few details about your property and energy consumption, and you'll receive tailored results that make the process simple and straightforward.

Our solar panel calculator can give you a great overview of solar panel costs and savings in the UK. However, the cost and savings of solar panels will be affected by potential extras and installation costs, which vary by installer.

How does the GreenMatch solar calculator work?

Our solar panel calculator will need your location, roof details, energy consumption, system preferences, financial information, and additional factors to estimate solar panel size, cost, and savings. Here’s how it calculates each metric:

Number of solar panels needed: The solar calculator considers your available roof space and energy consumption to determine the optimal number of panels. It factors in standard panel dimensions and efficiency ratings to maximise energy production within your available area.
Annual solar energy output: Using your location's sunlight measurement data and the proposed system size, the solar panel kWh calculator estimates your yearly kilowatt-hours (kWh) production. It accounts for factors like panel efficiency, roof orientation, and typical weather patterns.
Total cost of installation: The solar cost calculator estimates installation costs based on current market prices for panels, inverters, and other components. It also affects average labour costs for your area and system size.
Savings on your energy bill: The calculator projects your potential annual savings by comparing your current energy consumption and costs with the estimated solar energy production. It considers factors like electricity rates and any applicable feed-in tariffs.
Payback period: The calculator determines how long it will take for your energy savings to offset the initial installation costs. It takes into account projected energy price increases and panel degradation over time.

If, after using our solar panel calculator, you’re still wondering how many solar panels you need or if solar panels are worth it, we highly recommend speaking to a solar specialist who can give you tailored advice.

Frequently asked questions

How do you calculate how many solar panels you need?

How do you calculate the payback time of solar panels?

How do you calculate how much solar energy you will generate?

Written by Alejandro Staton Varela, Writer

Alejandro is a copywriter at GreenMatch and is passionate about European environmental policy and renewable energy. He has conducted research on the European Green Deal’s impact on EU energy policy and climate adaptation, and he is committed to using his writing skills to promote sustainable policies.