How do I read the payback period shown by the calculator?

The payback period is the number of years it takes for your cumulative savings on energy and fuel to equal your upfront or financed costs. Once this point is reached, all further savings are pure profit.

What is the export rate and how does it affect my savings?

The export rate (Smart Export Guarantee in the UK) is the price your energy supplier pays you for surplus solar electricity you send back to the grid. A higher export rate increases your annual income from solar and shortens the payback period.

Do I need battery storage for solar panels to be worthwhile?

Battery storage is optional. Without a battery, any solar electricity you generate but do not use immediately is exported to the grid at the export rate. A battery lets you store that surplus for evening use, which is usually more valuable than the export rate. The calculator lets you model both scenarios.

Can I use solar panels to charge my electric vehicle?

Yes. Charging your EV from solar-generated electricity during the day is one of the most cost-effective ways to reduce running costs. The calculator factors in your EV's annual mileage and efficiency alongside your solar system to show combined savings.

What costs does the calculator take into account?

The calculator combines your current electricity and fuel bills, any vehicle finance payments, and the cost of a solar system (upfront or monthly) and an electric vehicle (purchase, lease, or finance). It produces a side-by-side annual and long-term comparison.

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How to Use This Calculator

Follow these steps to get accurate cost comparisons

Current Costs: Enter your current electricity and fuel costs, plus any vehicle finance payments. You can input either your monthly/annual bills or calculate from usage.

Solar System: Configure your proposed solar panel system including number of panels, payment method (upfront or monthly), and battery storage capacity in kWh.

Electric Vehicle: Add details about your planned EV including purchase/lease/finance costs, annual mileage, and efficiency.

Calculate: Click "Calculate Savings" to see detailed cost comparisons, payback periods, and long-term savings including post-payoff benefits.

Solar Panel & Electric Vehicle Calculator

Compare costs and calculate savings from solar panels and electric vehicles

Electricity Costs

Enter usage instead of cost

Annual instead of monthly

Monthly Electricity Bill (£)

Electricity Rate (£ per kWh)

Current Vehicle & Fuel

Current Vehicle Status

Calculate from mileage

Annual instead of monthly

Monthly Fuel Cost (£)

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Understanding Solar Panel and EV Economics

How This Calculator Works

This calculator compares your current energy and transport costs with the potential savings from solar panel installation and electric vehicle adoption. It considers both upfront costs and ongoing savings to provide a comprehensive financial picture, including the benefits of battery storage for overnight EV charging.

Solar Panel Considerations

Solar panel systems in the UK typically generate 850-1000 kWh per kW of installed capacity annually. The calculator considers self-consumption rates, excess generation exported to the grid, and the Smart Export Guarantee payments you can receive for surplus electricity.

Average UK household uses 2,700-4,100 kWh annually
4kW system (10-12 panels) typically covers 70-80% of usage
Installation costs vary from £4,000-£10,000 depending on size
Battery storage adds £3,000-£8,000 but increases self-consumption to 90%
Smart Export Guarantee rates typically 3-15p per kWh exported

Electric Vehicle Integration

Electric vehicles work particularly well with solar panels and battery storage. The calculator accounts for increased electricity usage from EV charging but also considers how solar generation and battery storage can significantly reduce charging costs, especially when charging overnight with stored solar energy.

Average EV efficiency: 3.5-4.5 miles per kWh
Home charging typically costs 7-10p per mile without solar
Solar charging can reduce costs to 2-4p per mile
Battery storage enables cheap overnight EV charging from stored solar
Time-of-use tariffs can further reduce charging costs

Battery Storage Benefits

Battery storage significantly enhances the benefits of combining solar panels with electric vehicles:

Increases solar self-consumption from 70% to 90%
Enables EV charging from stored solar energy overnight
Provides backup power during outages
Allows participation in grid balancing services
Maximizes savings by storing cheap/free solar energy

Additional Financial Benefits

Beyond the direct savings calculated, consider these additional financial advantages:

Protection from rising energy and fuel prices
Increased property value from solar installation
Potential government grants and incentives
Reduced maintenance costs for EVs vs petrol cars
Lower insurance costs for some EV models
Potential income from grid services with smart systems

Important Note

This calculator provides estimates based on average UK conditions and costs. Actual savings will vary based on your location, usage patterns, system specifications, energy prices, and driving habits. The calculator assumes optimal system sizing and considers grid export payments at current Smart Export Guarantee rates. Consider getting quotes from certified installers for accurate cost assessments.