Why Your Solar PV System Is Underperforming (And What You Can Do About It)

Why Your Solar PV System Is Underperforming (And What You Can Do About It)

Introduction

Many solar PV systems I inspect are producing far less than expected—and the owner often has no idea.

In some cases, systems are generating 30–40% less than predicted.

The Symptoms

• Lower than expected generation

• Poor return on investment

• System appears to be working “normally”

• No visible faults

The Root Cause

Underperformance is usually caused by:

• Shading (often underestimated at install stage)

• Incorrect system design

• String configuration issues

• Inverter limitations

Technical Breakdown

In one recent case:

• Estimated generation: ~3,500 kWh/year

• Actual generation: ~2,000 kWh/year

That’s a ~43% performance loss.

Common causes:

• Trees not accounted for

• Incorrect orientation assumptions

• Poor panel layout

The Fix

• Full system performance analysis

• Identified shading impact

• Advised on system expansion and optimisation

The Result

• Clear understanding of system limitations

• Plan to improve generation

• Better long-term performance

Could This Be Happening to You?

• Your system isn’t meeting expectations

• Your FIT/export income is lower than predicted

• You’re considering adding more panels

Need Help?

I provide solar PV diagnostics, performance assessments, and upgrade advice across the Northeast including Durham, Teesside, North Yorkshire and Cumbria.