open source solar concentrator
so simply made of a bottle!
the cheapest you can find
open source wind turbine
http://www.treehugger.com/wind-technology/build-diy-wind-turbine-30.html
source:
http://forum.opensourceecology.org/discussion/72/a-simple-design-for-a-cheap-solar-thermal-collector/p1
and my old blog:
http://arqtect.blogspot.pt/2012/01/iluminacao-custo-zero.html
low cost solar concentrator bottle recycling
how a mirror improves the efficiency!
although careful because the heat reduces it and can bur the cells and reduce it's life!
light saving hack hacking technique
money saving
upvote r esteem sharing with your friends!
one more thing