Transwikied from- http://lifeafterpeople.wikia.com/wiki/Solar_Furnace
The largest solar furnace in the world is at Odeillo,France.It employs an array of plane mirrors to gather sunlight,reflecting it onto a larger curved mirror.It can reach temperatures up to 3,500 C'. How long can it last?
50 years after people:The Solar Furnace still generates power all over France.But that is about to change.The mirrors crack. The large curved one shatters off the building it sits on.As soon as that happens, France goes dark. The rest of the glass shatters. Only the crumbling structures remain, but then an earthquake shakes them down.