Solar Security Lights

Looking out of the window once the sun has gone down my garden looks pretty dark in some corners so I thought I'd better invest in some solar security lights. Before I did that I was trying to understand what would be the environmental impact of adding a load of solar lights to my garden. Obviously they're envrionmentally friendly because they don't use electricity but are they damaging the wildlife at all. I think it depends on where you place them and how bright they are. More on that next time.