The market is being flooded with poor quality "inserts". These quickly delaminate and become useless, as you will see from the photo opposite.

As well as being able to buy these, the public are unwittingly having them pre-installed into existing polycarbonate panels. Check where they come from and whether they are guaranteed.
 
We were called in by two customers to purchase our Solar Inserts, only to find these delaminated "inserts" already in their roofs!