Issues you may encounter when buying cheap flexible solar panels

Posted by Sammy on June 17th, 2019

Cheap flexible solar panels are made in a manner that keeps costs to minimum using a mixture of various cheap low grade cells, usually seconds.  Individual cells are graded for quality at the time of manufacture with the highest grade being A-grade cells.  Good quality solar panels only use high-grade cells, while cheaper panels use lower grade cells, possible C or D grade, or a mix of different grades cells to keep costs down. You can tell this by an inconsistency in the colour of the cells across the one panel.  Cells that are seconds may have cracks, chips and damaged surfaces.  

The junction boxes where the positive and negative cables connect with the panel and where the bypass diodes are fitted requires careful soldering and sealing with heat conducting sealant to prevent corrosion and to dissipate heat from the diodes.  Junction boxes in cheap panels rarely have more than one diode and are usually not sealed.  Moisture will quickly corrode the junction box internals when sealant is not applied.

The completed panels rarely go through quaity control and testing prior to shipment.

Case Study - Solar panels used by the caravan manufacturer 

We were asked to visit a caravan manufacturer as they were having a very high failulre rate with a well known cheap brand of flexible solar panels and they wanted an alternative.

Customers complaints about the solar system failing was not good for their caravan brand reputation.   The time, effort and cost in replacing the panels was significant.

When our Engineer was there they pulled a new panel from out of its packaging from the stock they were using so it could be examined.  The panel photographs below were taken from that one unused panel.