Solar calculator

Shape a system.
See every assumption.

Explore how usage, roof direction, battery storage and an EV change an indicative home system. This is an educational model—not a roof survey or installer quote.

Shape an illustrative system

£120a month
Main roof direction
Illustrative system

15

panels

6.6 kWp

array size

7 kWh

storage

6,138 kWh

estimated generation

£1,359

estimated annual benefit

£11,800–£14,600

indicative cost

Uses standard assumptions for panel output, self-consumption, import cost and export income. A roof survey and installer quote are still required.

Continue my estimate

Method

One model from first click to saved estimate.

The quick calculator and full postcode estimate share the same core maths. The full journey adds local solar resource and stores the result for quote comparison.

  1. 01

    Estimate demand

    Monthly spend is divided by an assumed 25p/kWh import rate. EV and heat-pump demand can then be added.

  2. 02

    Size the array

    The model selects enough 440 W panels to broadly match demand, within its domestic sizing limits.

  3. 03

    Model generation

    Regional solar resource is adjusted for roof direction and reported shading. The full estimate uses postcode-level data when available.

  4. 04

    Value the energy

    Solar used at home avoids imported electricity; surplus is valued at an assumed 12p/kWh export rate.

Important limits

Useful for orientation. Not for engineering sign-off.

The model does not inspect roof dimensions, structural condition, cable routes, DNO requirements or equipment compatibility. Tariffs and actual household behaviour can materially change the outcome.

Add my postcode and roof