# What size solar system does your business need?

A commercial solar system is sized around how much electricity you use and when, not just your available roof. The aim is to maximise self-consumption — using as much of the generation on site as possible — because that is where the savings come from. Bigger isn’t automatically better.

## Sized to your demand, not just your roof

The best system matches your usage pattern so most of the generation is consumed on site. An oversized array that exports a lot of cheap surplus earns far less than one tuned to your actual daytime demand.

## Roof and site set the ceiling

Available area, orientation, shading and roof condition cap how much you can install. A good design balances those constraints against your load to find the sweet spot.

## Battery storage changes the maths

Adding a battery lets you use more of a larger system by storing daytime surplus for the evening — so storage can justify a bigger array than solar alone.

## Frequently asked questions

**Should we fill the whole roof with panels?**

Not necessarily. The most cost-effective system is sized to your demand so you use most of the generation. If you add battery storage, a larger array can make sense. We model this for your site.

**How do you work out the right size?**

From your consumption data, tariff, roof and goals. That lets us design a system that maximises self-consumption and return, which we set out in a free proposal.

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Source: [What size solar system does your business need?](https://ppafunding.com/guides/what-size-solar-system-does-my-business-need) · Author: PPA Funding team · Updated: 2026-07-30

PPA Funding is an independent introducer operated by DVC Group Ltd (Companies House 10462808), Shrewsbury — not the funder, the installer or the maintenance provider. The service is free to use; a commission may be earned from a partner at no extra cost. Content is educational and is not financial or tax advice.