Once, ispired by this (skip to 32:30), I quickly made a small solar parabolic mirror: https://www.youtube.com/watch?v=Bh4n6QzX9S0 https://www.youtube.com/watch?

Once, ispired by this (skip to 32:30), I quickly made a small solar parabolic mirror: https://www.youtube.com/watch?v=Bh4n6QzX9S0 https://www.youtube.com/watch?v=Bh4n6QzX9S0 and it worked nicely (to set to fire some wood). Admittedly the sunshine in Southern Italy where I tested that (or Andalusia, Southern Spain, as in the TV program above) is probably much different from the one in Sweden, but on a good day it is most probably strong enough even in North Europe.