Solar panel review
Updated 16/09/2025
We have installed a significant number of solar panels domestically and commercially since 2009. To our knowledge we have only had four panels fail. One solar panel failed due to a manufacturing defect and was replaced under warranty. Another panel failed due to mechanical damage rather than a manufacturing fault. The final two panels failed due to faults with the internal electronics – one of the blocking diodes.
Low pitched roof
Pools of water on the glass make the glass turn white and over time causes a reduction in performance. Also water pooling encourages algae growth, which would require regular cleaning. Therefore many manufacturers recommend a minimum installation angle of 10 degrees to allow dust to be washed off by the rain.
Panasonic used to offer solar panels where the frames had cut-outs to allow water to drain off more easily but these are no longer available.
Short of roof space
Chose a panel that is more efficient such as:
When comparing solar panels look at module efficiency, since cell efficiency doesn’t give you the full picture.
Higher output solar panels such as 510W panels are not necessarily more efficient – watts per m² is the important measure (module efficiency %).
Solar panels come in different shapes, so sometimes the highest the most efficient panel is not always the best solution.
Value for money
In 2009 we only installed European manufactured solar panels such as Sharp, REC and Q-Cells. Things have changed dramatically and China now produce very high quality products.
The largest 10 solar panel manufacturers in the world now all come from China. Here are the top 7 in 2025:
- 1
Jinko (China)
- 2
LONGi (China)
- 3
JA Solar (China)
- 4
Trina Solar (China)
- 5
Canadian Solar (China)
- 6Chint Solar (China)
- 7Suntech (China)
All of the top solar panel manufacturers are very similar in quality and price.
Brand
Historically, we recommended household names such as Sharp, LG, SunPower and Panasonic. With the changes to the solar market, we now normally recommend JA Solar, LONGi and Aiko.
European manufactured
Due to strong competition from overseas, a large number of German companies have left the market such as Axitec, Conergy, Solar Fabrik, Romag and SolarWorld. It is therefore a sad situation not to be able to recommend a European company without the real risk of losing your warranty.
Whilst Hunhwa Q Cells is no longer a German company, they do their research and development in Germany and manufacturer in South Korea.
REC panels are manufactured in various locations including Singapore, Norway, Canada, and Japan.
Examples
Q Cells Q.TRON Q.ANTUM NEO 445W All Black, REC Alpha Pure-RX 470W All Black
Slate roof or listed building
Chose an all black panel (which often means mono crystalline cells), black frame and black back sheet. The back sheet is the sheet of plastic behind the solar cells. Alternatively, an all black double glass bifacial panel.
Solar panels with back contacts do not have the shiny solder lines running across the panel.
Warranty
A shorter warranty from a top branded panel may be worth more than a longer warranty from an unknown company.
A performance warranty is largely irrelevant since the warranty terms and conditions often make this warranty very difficult or expensive to claim. A performance warranty is to ensure the performance of the panel doesn’t fall too much over time.
A product warranty is to protect against the solar panel or parts failing – a product warranty of 15-20 years or more is now standard across the industry.
