What size system do I need?

Answer a few quick questions for a guide to the solar, battery or heat pump size that could suit your home. It takes about a minute.

A guide only, based on typical UK figures. It is not a quote or a survey. An MCS-certified installer will size your system properly after assessing your home.

How we work this out

We believe in showing our working.

  • Electricity use

    We start from Ofgem’s typical household figure of 2,500 kWh a year, with lower and higher bands, plus an allowance if you’re planning an electric car or heat pump.

  • Solar generation

    We assume around 900 kWh a year per kW of panels on a south-facing roof, reduced for east, west and north-facing roofs.

  • Roof space

    We cap the number of panels by the roof size you choose, using a typical 430 W panel.

  • Export and savings

    We estimate how much solar you use at home (more with a battery or if someone’s in during the day) and value it at your electricity price. The rest is valued at your export rate. Both are yours to adjust.

  • Heat pumps

    We start from typical sizes by number of bedrooms and adjust for your type of home and insulation. A heat loss survey gives the real answer.