By the PPA Funding team Last updated
As a rough guide, commercial solar needs around six to eight square metres of usable roof per kilowatt installed, so a large warehouse roof can host a very sizeable system. What matters most is not just area but orientation, shading, and the roof’s condition and structure.
Area is only part of it
Usable area sets the ceiling on system size, but a good design also considers roof pitch and orientation, shading from plant or nearby buildings, and how the roof is constructed. South-facing is ideal, though east-west layouts work well for spreading generation across the day.
Roof condition and structure
The roof needs to be sound and able to carry the additional load. We assess condition and structure as part of the design, and where works are needed they can often be included in the funding.
Limited roof? Consider battery or ground-mount
If your roof is small or unsuitable, a standalone battery can still cut costs, and some sites suit a ground-mounted array on spare land. We recommend the best route for your specific site.
This guide is general information, not financial or tax advice. Your circumstances determine what applies — please confirm with your accountant or advisor. Get a tailored proposal →
Frequently asked questions
My roof faces east-west, not south — is that a problem?
Not at all. East-west arrays spread generation across the morning and afternoon, which often matches business demand well. South-facing simply peaks at midday. We design to your roof and load.
What if my roof needs repairs first?
Roof works can frequently be folded into the project and funding, so the roof and system are handled together. We assess this as part of your free proposal.
Related guides
- DNO approval and G99 for commercial solar explained
- Commercial solar maintenance: what’s actually involved?
- How long do commercial solar panels last?
See our funding options, commercial solar and solar by industry pages.