ECONOMIC EVALUATION AND OPTIMIZATION OF SOLAR HEATING SYSTEMS

Abstract

Life cycle cost analysis is used to evaluate economic comparisons between residential solar heating systems and conventional heating systems. The comparison is expressed as the life cycle savings of the solar system over the conventional system. A procedure which simplifies the life cycle cost comparison is developed by introducing two economic parameters, P1 and P2. These parameters relate all life cycle considerations to the first year fuel savings or the initial solar system investment cost. They can accommodate arbitrary time variation of annual costs and discounting of future costs to present dollar values, while expressing the life cycle savings equation in a compact form. Assuming a linear relationship between the solar system investment cost and the collector area, the simplified savings equation is optimized with respect to collector area. Straightforward manipulation shows that the optimum condition is defined by one economic parameter for a given location and collector type. Using the f-chart design method, tables are generated which give the optimum collector area to annual load ratio, and the optimum load fraction supplied by solar energy, as a function of this economic parameter. This non-iterative optimization procedure is applied to a standard domestic water heating system, a combined space and domestic water heating system with air as the transfer-medium, and a combined system with liquid as the transfer-medium.