If birds are an issue (or likely to be an issue in the case of new solar installations), solar panel bird proofing should be installed in the form of mesh on all sides of the array. Note that solar panel protection is harmless - it simply encourages the birds to hang out somewhere else.
Spiffy Solar Products should be installed which are specifically designed for wildlife abatement systems, firstly because they are penetration-free and secondly ensure your customer’s panel warranty isn’t voided by drilling into the panels in order to attach screen.