A well designed and installed solar PV system should deliver reliable, consistent energy for decades. However, many homeowners notice a drop in output over time and are unsure why. Understanding the most common causes of solar panel performance loss can help you protect your investment, maintain high solar panel efficiency and maximise long term savings.
Below, we explain the key factors that can reduce performance and what homeowners across Essex, Kent and Suffolk can do to prevent them.
Dirt, Debris and Bird Droppings
One of the most common and overlooked causes of reduced solar panel performance is surface contamination. Dust, pollen, moss, salt residue (particularly in coastal areas) and bird droppings can block sunlight from reaching the photovoltaic (PV) cells.
Even partial shading on a solar panel can significantly reduce output, up to 15% in some cases. Older systems without panel level optimisation suffer the highest output effects from dirt and debris. Reduced sunlight absorption, lower overall system yield and gradual decline in annual performance all affect a panel’s efficiency over time.
Solution:
Regular professional cleaning and visual inspections help maintain optimal solar panel efficiency, particularly after dry summers or stormy winters.
Shading from Trees, Buildings or New Obstructions
Solar panels rely on unobstructed sunlight. Trees grow, extensions are built and neighbouring developments change rooflines. Even small amounts of shade at certain times of day can significantly reduce the output of an entire solar PV system.
This issue is particularly common in suburban areas where mature trees are prevalent. Shading causes disproportionate energy losses and reduced reliability during peak generation hours.
Solution:
A professional shading assessment can identify problem areas. In some cases, trimming trees back or upgrading your system to include power optimisers can significantly improve your solar panel performance.
Inverter or Electrical Component Degradation
While solar panels themselves are highly durable and have long lifespans, inverters and electrical connections typically have shorter lifetimes. A failing inverter can cause intermittent generation or complete loss of output, often without notice or signs.
Impact on reliability:
- Inconsistent generation
- Lower system uptime
- Reduced export and self-consumption
Solution:
Routine system health checks and monitoring ensure faults are detected early, reducing downtime of your system and protecting the long term reliability and efficiency of your solar PV system.
Natural Panel Degradation Over Time
All solar panels experience gradual degradation, with most high quality panels losing around 0.3-0.5% efficiency annually. However, poor quality installations or inferior products can degrade faster.
Impact on efficiency:
- Slight year on year reduction in output
- More noticeable losses after 10-15 years
Solution:
Choosing reputable installers who use premium components is critical. SolarTherm UK designs systems for long term solar panel reliability, we only install products that we have tried and tested over the last 15 years with strong warranties and measurable results. Simply put, if we wouldn’t install it in our homes, we won’t be installing it in yours.
Poor Original System Design or Installation
Incorrect panel orientation, sub-optimal tilt angles or mismatched system components can cause performance losses from day one. Unfortunately, this is still common with rushed or low cost installations, especially those that aren’t MCS accredited.
A poorly designed or installed system can cause your system to underperform, resulting in missed generation and a slower return on investment.
Solution:
Choosing an MCS accredited installer is the first step. If your system has already been installed a professional performance review can identify design limitations and recommend upgrades to improve solar panel efficiency.
Weather Related Wear and Environmental Factors
Homes in Essex, Kent and Suffolk are exposed to wind, rain, frost and temperature fluctuations. Over time, these conditions can loosen fixings, degrade cabling or cause micro-cracks in panels, especially if not installed correctly.
Over time these can result in gradual efficiency losses above the level of natural degradation and can lead to a higher risk of faults and repairs.
Solution:
High quality mounting systems and periodic inspections ensure your solar panel system remains secure and weather resilient.
How to Protect Your Solar Panel Performance
Maintaining strong solar panel performance is not about reacting to problems that occur, it’s about preventing problems from happening. Regular servicing, monitoring and professional support ensures your system continues to operate efficiently for decades.
At SolarTherm UK, we support homeowners across Essex, Kent and Suffolk with expert installation, performance checks and system optimisation to protect efficiency and maximise savings. If you are concerned about declining output or want to ensure your solar PV system is performing at its best, our team is here to help.
For installation enquiries or to start your solar journey, contact SolarTherm UK today for a free, no obligation quote and design, tailored to your property, usage and future energy needs. No hard sell, just honest, expert advice.
Your home. Your energy. Your future.
