I found 2 articles on the mounting of solar panels on roofs, often these mountings are not safe.
Here are the links to the articles:
http://www.duurzaamgebouwd.nl/onderzoek/20140326-veel-zonnepanelen-onveilig-bevestigd
The panels should not be mounted on the batten or roof deck but instead on the constructive parts of the roof (purlins), this in a direct or indirect way. When people mount there panels on the batten or roof deck the own weight of the panels or the wind can cause forces which are not acceptable and can lead to damage and unsecure conditions whereby there can fall parts of the roof.
When I start browsing for more information on this topic there are more articles describing this issue, all the articles are recent. I expected that there recent was an accident with solar panels but this is not the case, there are not many known cases of this problem.
– Jelle Leten
solarcleanenergy 
I can imagine that an unsafely mounted solar panel would detach during an extreme weather environment. I can than imagine a lot of people not really thinking much of it and thus is not getting a lot of attention. Do you know if these ‘unsafely’ mounted panels are put there by the consumers themselves? Or that a lot of companies that sell them are not aware of the correct mountings themselves?
Not alot of consumers place there solar panels themself. A lot of the companies just mount them incorrect this has two main reasons: they don’t know it’s unsafe and second it’s easier and cheaper to mount them in an unsafe way.