Cold-Climate Solar Domestic Water Heating Systems: Life-Cycle Analyses and Opportunities for Cost Reduction

To determine if the goal of 50% reduction in the cost of saved energy (C_sav) is attainable and prioritize research and development (R&D) for cold-climate solar domestic water heaters (SDWH), life-cycle analyses were done with hypothesized lower-cost components in glycol, drainback, and thermosiphon systems. Balance-of-system (BOS) measures include replacing conventional metal components with polymeric versions, and system simplification. With all BOS measures in place, C_sav could be reduced just over 50% with a low-cost, selectively-coated, glazed polymeric collector, and slightly under 50% with either a conventional selective metal-glass or a non-selective glazed polymer collector. The largest percent reduction in C _sav comes from replacing conventional pressurized solar storage tanks and metal heat exchangers with un-pressurized polymer tanks with immersed polymer heat exchangers, which could be developed with relatively low-risk R&D.