Fantastic!
I have a five year old daughter - she might be a little young for this right now, but I'm sure she could pick it up quickly.
What a brilliant way to get kids interested in:
a) solar energy & its potential uses
b) creative problem solving and building kits
c) outdoor activities - like swimming!!!
Because those boats don't look like they have any steering - and we live close to a river.
So, unless the sun goes down pretty quickly, one of us may have to fish it out (if it can be caught). And my money's on her - what a great way to combine building kits with learning to swim!