Many homeowners assume that if their solar inverter is on and generating power, everything is fine.
In reality, some of the worst-performing solar systems are the ones that are quietly underperforming — without obvious faults or error messages.
Signs Your Solar System May Be Underperforming
Common warning signs include:
Lower-than-expected generation year on year
Big differences between similar nearby systems
Export payments lower than anticipated
Inverter running but output feels “flat”
No panel-level monitoring data
Underperformance is often gradual, making it easy to miss.
Why Underperformance Often Goes Unnoticed
Most systems are only checked at installation. After that:
Monitoring apps aren’t reviewed
Seasonal performance isn’t compared
Minor faults aren’t flagged
Shading changes over time
A small design or configuration issue can quietly reduce output for decades.
The Cost of Long-Term Underperformance
Even a 10–15% reduction in annual output can add up to thousands of pounds in lost generation over a system’s lifetime.
That’s why performance monitoring and proper commissioning matter just as much as installation.
What Homeowners Can Do
If you suspect underperformance:
Review your monitoring data
Compare generation against system size
Check for shading changes
Seek a professional system health check
In many cases, performance can be improved without replacing the entire system.
