Commercial solar ROI calculator UK

Model indicative generation, on-site consumption value, export, operating allowance and simple payback for a commercial solar project.

WHAT THIS CALCULATOR TELLS YOU

Commercial solar economics are usually strongest when a business can consume a high proportion of generation on site. Half-hourly demand, roof/site constraints, grid connection and the actual project cost are more useful than a generic “business solar saving” claim.

Method reviewed: September 2026Assumptions are visibleIllustration, not a quotation

Outputs are simplified illustrations using the values you enter. They are not a prediction or guarantee of generation, savings, battery performance, charging cost or investment return.

HOW THE CALCULATION WORKS

Transparent methodology

Generation

Array size × your entered annual yield assumption.

Annual value

Avoided import cost for on-site solar + entered export value − O&M allowance.

Simple payback

Indicative project cost ÷ net annual value.

HOW TO INTERPRET IT

Use the result as a scenario.

A warehouse and an office can use the same annual amount of electricity but have very different solar economics if their daytime demand profiles, roof areas or import prices differ.

For a real project, replace planning assumptions with site-specific design data, current tariffs, actual equipment specifications and a formal quotation.

CALCULATOR QUESTIONS

What the tool can — and cannot — tell you

Why is half-hourly data useful?

It shows when electricity is actually being consumed, helping a designer model realistic solar self-consumption rather than relying only on annual totals.

Does simple payback include finance or tax?

No. Those are project- and business-specific and should be modelled separately.

What else affects commercial feasibility?

Roof structure, landlord/tenant arrangements, connection constraints, export limits, operating hours, future load and equipment specification can all matter.