After nine years of development, Rhotech Solar has completed a design for a low-cost solar collector capable heating water for your home. The design is efficient and low-cost enough to achieve a estimated return on investment of less than five years.
The design is made up of two parts: a collector and a polymer heat exchanger. The collector is a flat, flexible panel approximately four feet wide and ten feet long. The polymer heat exchanger is a set of thin-wall plastic tubes which are joined together at the ends to a single 3/4″ NPT fitting. The polymer heat exchanger serves as the interface between the collector and the water-mains.
A Novel Design
The current market for domestic solar water heaters is dominated by expensive systems which do not employ thinfilm polymers. A thin-film polymer solar water heating system has several advantages compared to traditional systems. Thin-films decrease system weight to below 10 kg (lowering shipping and installation costs), they can be produced using high-volume processing equipment (for example as used to produce plastic bags or packaging), and are very economical (projected installed costs are below $1000).
Product Comparison
| Product | Use | Energy Savings (BTU/day)1 | Peak Measured Temperature1 | Maximum Temperature2 | Life Expectency |
|---|---|---|---|---|---|
| All products include a heat-exchanger 1 Temperatures and energy savings observed in South San Francisco at ~75°F ambient 2 Operating temperatures over 176°F will reduce product life expectency |
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| Unglazed | Economical, best in mild climates | 7,500 | 130°F | 176°F | 10-15 years |
| Glazed with Heat Rejection | High-performance in all climates | 10,500 | 150°F | 176°F | 8-10 years |
| Heat-exchanger | Transferring heat to or from a medium | N/A | N/A | 176°F | |