After blowing (what I consider) a lot of money on 2 residential solar water heaters, over the last 6 years, dealing with 3 set of rather expensive inner-tank replacements, evacuation pipe changes I am considering a DIY approach, using good quality materials to make one on my own. The water we use is underground water, and it is hard water.

Having never attempted something of this sort, I was wondering if anyone has tried to make a Solar water-heater, successfully that would work (almost) as well as the factory produced ones ?

My requirements are about 100 liters per day, of hot water. What I am thinking of doing is buying a good quality parts (casing, PUF insulation material, inner steel/copper tank etc.) of regular electric water heater, of about 100L capacity (which costs about a third or fourth of what a solar-heater costs), remove the electricals, and make my own heat-collector using copper pipes, painted black, within a suitable enclosure (perhaps wooden), with glass top and 3 inner sides painted black, to trap heat. The hard part, for me, would be the copper pipes, i.e. cutting and fitting the collector arrangement.

Could this be something that might work ? I expect this DIY to cost about half of a factory made Solar water heater.

EDIT:

Here's some material I found on the subject here. Looks like it is doable and other have done it before, though not necessarily using the regular electric water-heater parts.