This is an article written by Doug Kalmer about his friend's DIY solar hot water heater, and follows on from his experiences with his own system:
"My 10+ years of success with solar hot water made my friend Bob want a similar system for his new house. Through word of mouth, I heard about someone in Huntsville who had a four panel solar system free for the removal.
It was installed in the early 80`s and heated domestic hot water, had fan coil units for space heating, and heated an inground pool. The systems installed then used electronic controls to operate valves and pumps, commonly the controls develop problems and parts and knowledgeable service techs are hard to find.
Bob and I spent a long hard day removing the panels, two 120 gallon tanks, three heat exchangers, much copper piping, valves, pumps, etc. We planned on using the components to assemble more modern systems using a Photovoltaic (PV) 12 volt panel directly wired to a DC pump to eliminate the controls and use of external electrical inputs- meaning stand alone systems using only solar energy to heat and circulate a non-toxic antifreeze to the Heat Exchanger (HE). The HE then uses only gravity to circulate tap water through it, heating the 120 gallons in the insulated tank. This is called a closed loop, PV pumped solar hot water system.
Bob has tubing running through the concrete slab of his home, he can have the heated antifreeze either just heat domestic water, or the slab for space heating, or both. That`s why he`s using two panels, one panel and a smaller tank would be sufficient for just domestic hot water for families of up to five. Each panel is nearly 40 square feet. Bob never soldered copper pipe before, but he did a good job of reusing as much tubing as he could.
All attached pictures are before Bob insulates all piping and the HE. Bob`s main expenses were for the 12v PV panel and pump. I used a 10 watt panel on my similar system, Bob chose a 30, I feel this is larger and more expensive than necessary. The pump is mounted close to the PV panel, Bob and I modified an ammo box to house it. I built the rack to support the panels. This sort of reliable system can be put together for considerably less cash than buying a complete system, it just requires hard work and the willingness to learn. Free heat and hot water from the sun!