Solar Panel Lease vs Buy Calculator

How this calculator works

This calculator works in ranges rather than single figures, because real quotes, yields and tariffs genuinely vary that much. It starts from typical UK price, output and savings ranges drawn from published 2026 industry guides and official scheme documentation, then scales them by the quantities you enter and adjusts them for each choice you make below. The result is a low-to-high band that a realistic outcome is likely to fall within, not a promise of the figure you will achieve.

Buying a 4 kWp system outright costs roughly to upfront plus modest maintenance, a 25 year all-in cost of around to . Solar subscription and lease plans typically charge to a month for a similar system, which compounds to roughly to over 25 years, so ownership is usually significantly cheaper in total, and the owner rather than the provider keeps all the savings and export income from day one.

System size

Solar systems are sized in kilowatts peak (kWp), the output of the panels under standard test conditions. A 4 kWp system of around 10 modern panels is the most common choice for a UK three bedroom home, while larger households, or homes with an electric vehicle or heat pump, often go to 6 kWp or more. Bigger systems cost less per kWp because fixed costs such as scaffolding, the inverter and installer overheads are spread across more panels, and the calculator reflects that economy of scale.

Where you live

Installation labour is not priced uniformly across the UK. Published guides put London and South East installation costs roughly 15 to 25 percent above the national average, reflecting labour rates, access and parking. Hardware prices are broadly national, so the difference is mostly in the fitting.

What else affects the figures

Leases and subscriptions exist because they remove the upfront cost: the provider installs and maintains the system, and you pay monthly, ideally less than the bill savings. The detail deserves scrutiny, since contracts commonly run 20 to 25 years, may include annual payment escalators, can complicate selling the house because the buyer must take on the agreement, and may leave export income with the provider. If avoiding upfront cost is the goal, it is worth comparing a lease against financing ownership instead, through 0 percent or low-interest green home improvement loans, where the loan repayments buy you an asset rather than a service.

Certification, planning and grid connection

Most home solar installations fall under permitted development and need no planning permission, provided panels do not protrude more than 200 millimetres from the roof plane, though listed buildings and flats have tighter rules and conservation areas restrict panels on walls fronting the highway, so check with your local planning authority if any apply. Use an MCS-certified installer: certification is required to register for Smart Export Guarantee payments and is the industry marker of a compliant installation. Your installer must also notify or seek approval from the district network operator, automatically for systems up to 3.68 kW per phase under G98 and by prior application under G99 above that. Residential solar and battery installations carry 0 percent VAT until 31 March 2027, after which the rate is due to revert to 5 percent.