Commercial Solar Panels — How Much Roof Space Do You Need?

HPC Renewable Energy
Nov 25
2 min read

Introduction

Commercial solar panels are rapidly becoming one of the best investments UK businesses can make. But one of the most common questions we hear is:

“How much roof space do we need for commercial solar panels?”

This guide explains how much space is required, what affects capacity, and how to estimate what your building can support.

How Much Roof Space Do Solar Panels Need?

Most modern commercial solar panels are 500–600W and measure around 2.2m x 1.1m, requiring roughly 2.5m² per panel.

Quick Reference: Roof Space Requirements

System Size	Panels Needed	Space Required
10 kW	~18 panels	~45 m²
30 kW	~55 panels	~140 m²
50 kW	~90 panels	~225 m²
100 kW	~180 panels	~450 m²
250 kW	~450 panels	~1,100 m²
1 MW	~1,800 panels	~4,500 m²

(Estimates depend on orientation, shading & roof layout)

Key Factors That Affect Roof Space

1. Roof Shape & Usable Area

Obstacles like:

Skylights
Vents
AC units
Parapets

…reduce usable mounting space.

2. Panel Efficiency

Higher-efficiency panels = more power from fewer panels.Premium modules (e.g., 22–23% efficiency) are great where space is limited.

3. Orientation & Pitch

South-facing roofs are ideal.
East/West roofs still work well for businesses with long operating hours.
Flat roofs allow adjustable mounting.

4. Structural Load

A structural survey ensures the roof can handle:

Panel weight
Racking
Wind lift
Snow load

How to Estimate Your Roof’s Solar Potential

Step-by-step:

Measure the roof dimensions
Calculate total area
Subtract unusable space (10–30%)
Divide the remaining area by ~2.5m² per panel
Multiply panel count by 500–600W

We can do this calculation for you and produce a full feasibility report.

Case Study Example

A warehouse with 1,000 m² of usable roof space can typically support 180–220 panels, giving a system size of 100–130 kW.

This can save £15,000–£30,000 per year depending on energy usage.

Conclusion

Roof size plays a major role in determining commercial solar potential, but even smaller roofs can deliver strong savings with modern high-efficiency panels.