Appropriate Sizing of Solar Heating Systems

Abstract

It is generally assumed that a solar heating system should be sized by minimizing its life-cycle cost. This study shows, however, that the uncertainty in future economic trends makes the results of such a procedure questionable. The design conditions for minimum cost are extremely broad and all practical systems have a solar fraction within the limited range of 30 to 90 percent. Thus, by choosing only three collector areas that give systems within this range, one is assured of selecting a nearly optimal system for any realistic economic scenario. Selecting one of these three systems is essentially equivalent to economic optimization, but simpler. Procedures are derived in this paper for determining the sizes of the three systems. The conclusion is that the collector areas should be about 1/8, 1/5, and 1/3 of the building floor area. This rule of thumb eliminates the need to design solar systems individually, allowing the possiblity of mass-produced homes with standardized solar heating systems.