Tests on a domestic solar system that was installed and connected 20 years ago reveal that it still has a 95% generation rate from its initial installation.
The 2.16kW array is south facing on an oak frame with 36, Solarex 60Wp, polycrystalline modules, and an SMA PV WR-1800 inverter – the first SMA inverter installed in the UK.
After 20 years, Wind & Sun who installed the system, performed a range of tests on the solar panels and a comparison in performance was made against the original panel flash test data when it left the factory.
The system was predicted to decline in efficiency by 20% from the panel’s original performance over 20 years. However, the first panel test revealed there had only been a 5% decline.
When the entire array was tested, accounting for shading of nearby overgrown trees and debris build up, the panels still performed at 80% of the systems original output.
The system has generated 33MWh with no faults for the last 20 years, although an inverter upgrade of the Sunny Boy SB-2500 was fitted in 2008.
The solar system was grid connected 27 July 1994 after the local grid company, EMBD, approved the idea and is the first UK demonstration of harnessing solar energy to supply the national grid.
Rooftop solar installations are now common across the UK and since 1994 solar installation costs have plummeted, and payback time is now around 5 years.
In 1994 the system cost was £6,900 per kW with a module cost price of £4.40 per watt – totalling a 200 year payback time.
Steve Wade, Wind & Sun’s managing director said: “The progress we have made in the last 20 years has been exceptional and it is amazing to see more and more solar systems appearing everywhere thanks to the vision of some pioneering individuals. We expect that this system could be producing for at least another 20 years. Solar is now firmly established as a mainstream energy source and we can now look forward with confidence to a sustainable future."
This article has been adapted from an article published in Solar Power Portal.