Solar Savings Calculator

Use our free solar savings calculator to estimate how much a solar panel system could save you each year. Adjust the system size, your region, electricity tariff, and self-consumption rate to see personalised results instantly. The calculator uses real UK sunshine data and current electricity prices to give you an accurate picture of your potential savings and payback period.

How We Calculate Your Savings

Our calculator uses the same methodology as every postcode page on SolarCheck.uk. Here is how each figure is derived:

• Annual generation is calculated as system size (kW) x sun hours x 0.7. The 0.7 factor accounts for real-world losses including inverter efficiency, shading, temperature derating, and panel degradation.
• Self-consumed electricity offsets what you would otherwise buy from the grid at your current tariff rate. This is typically the largest component of your savings.
• Exported electricity earns income through the Smart Export Guarantee (SEG) at an average rate of 12p/kWh. Actual SEG rates vary by supplier — some offer up to 15p/kWh.
• Payback period is simply the total system cost divided by your annual savings. Most UK homes see payback within 6 to 9 years.
• 25-year profit sums up savings over 25 years (the typical panel warranty period), applying 0.5% annual panel degradation, then subtracts the upfront system cost.
• CO2 savings are based on the UK grid carbon intensity of approximately 200g CO2 per kWh.

Tips to Maximise Your Savings

• Increase self-consumption by running high-draw appliances (dishwasher, washing machine, EV charger) during daylight hours when your panels are generating.
• Add battery storage to capture surplus daytime generation for evening use. This can push self-consumption from 50% to 80% or more.
• Choose the right system size — a larger system generates more electricity but has diminishing returns if you cannot use or store the extra power.
• Compare SEG tariffs across suppliers. Octopus, Tesla, and others frequently offer rates above the 12p average.