Make your roof part of the plan

Solar panel savings calculator

Explore a solar proposal using the system size, generation and costs you choose. Change the assumptions to see what makes the biggest difference.

No email requiredYour numbers, visible assumptionsResults stay in your browser

Make it your scenario

The starting values are examples. Replace them with your bills or installation proposal.

Proposed solar size · kWp

Panel capacity, not annual generation. Use the system size on a proposal.

Annual generation per kWp · kWh

An illustrative starting value. Replace it with the survey estimate for your roof.

Generation used directly at home · %

Before adding a battery. The rest is assumed to be exported.

Electricity import rate · p/kWh

What you avoid paying for each unit used directly.

Electricity export rate · p/kWh

Example only. Enter a tariff available to your installation.

Full installed cost · £

Include scaffolding, inverter, electrical work and VAT where applicable.

Put the result in context

Understand the full solar installation

Read the guide ↗

The working, made visible

How this tool works

Generation = system size × annual yield. First-year value = electricity used at home × import rate + electricity exported × export rate. Simple payback = installed cost ÷ first-year value.

What to allow for

This models solar without a battery. It excludes finance, maintenance, replacement equipment, degradation and future tariff changes. Export availability, shading, roof area and system suitability need a site assessment. Default numbers are examples, not live market prices.

Energy Saving Trust: solar panels ↗