holes appearing in polycarbonate roof

[cazza59]

have a polycarbonate roof on my conservatory which is 24ft x12ft its a lean to style conservatory..over the past 2 years we have seen holes appearing on the outer surface .my neighbour said it may be because it is so hot in our c/tory and its expanding i cant see that myself because surely it wouldnt create holes!! do you have any idea what it might be..also if it gonna be an ongoing problem( as we already had 3 panels replaced and it still happening)what is the name of a good product that keeps the heat off the roof... :? thank you