DIY Solar Hot Water Heat Kit For About $30
The tubing is 5/8" irrigation pipe I bought at Lowe's. I bought three 100' sections for $10 each. The concrete under is my cesspool tank cover. The glass is from a sliding door that the salesman at Lowe's gave me (he bought a new one for his home).
The water comes out scalding hot, so I think plastic sheeting could be used instead of glass. The water enters the coil system from my water pump, and returns to the house at any hot water line.The tubing holds about 5 gallons of water, but is so hot that when mixed with cold water at the shower valve I can get a pretty decent shower. I have thought of using a circulating pump and a tank to store up hot water but so far I am just using the coil itself as the holding tank.
There is no county water on my property. I buy 4000 gallons of water for $140, and store it in a tank. 4000 gallons lasts about 4 months. A short shower saves on the water bill. Most of my water goes into the landscaping.
Electricity is 30 cents per kilowatt in Hawaii. I think the payback period for my solar hot water heater is about 2 weeks. After 2 months the pressure in the pipes blew out the plastic connectors between the 100' sections. So I switched to brass barbed hose repair kits with stainless hose clamps. They cost about $1.50. Don't use plastic fittings as they will not last.
This entire project cost about $30 not bad considering it is used to offset a significant amount of energy costs and has already paid for itself.
Obviously in a colder environment you would need to make the enclosure more insulated, and you would have to worry about freezing, but in warm climates this set up could solve all of your hot water needs.
Enjoy the hot water.