Homemade solar hot water

[MarkP]

I think it will work, as long as you practice whatever degree of conservation is necessary so that the solar heat can keep up. Many people fail at this critical step and are then disappointed, having unwittingly compared the solar system with the old conservation-be-damned system. In fact I think I have read of building solar water heaters in this way. You should build a simple glazed and insulated box to put the old water heaters in. I put one of those plastic bag campng solar showers in the back of my car once at the beach. Insulated from the wind, the water got scorchingly hot, too hot to use undiluted.