This is a great DIY Solar water heater project. Solar water heat may not be a sexy as solar electricity but it produces a lot more energy savings for the dollar and is something everyone can do. See how to build it here.
1. The collector is easy to build using ordinary tools and skills — its a fairly easy DIY project.
2. The collector is about 1/5 th the cost of commercial collectors ($140 vs $700 to $900 for a 4X8 collector)
3. Materials to build the collector are locally available — the cost and hassle of shipping large assembled collectors is avoided. Shipping on a commercial collector is more than the total cost of materials for the PEX collector!