I'm sure it's an issue if the system isn't designed to prevent it.

There was a building in Las Vegas I believe that was accidentally designed in such a way that it magnified sunlight and directed it at a place where people sat during the day. Not exactly a great headline if you accidentally cook some patrons alive. Thankfully it was caught before anyone was seriously injured.

It just happened to be a curved surface on a shiny building that at a certain time of the day reflected right on customers.

Similarly, a bottle catching the light just right can start a fire.

The sun is a powerful thing. If you're going to harness it in such a way to heat stuff up to an extreme degree, you have to be very careful...or you'll accidentally roast some chicken...or duck...or seagull...