Comparative analysis of economic models in selected solar energy computer programs

Abstract

A variety of computer simulation programs exist for the design and study of thermal performance and economic feasibility of solar domestic hot water and space heating systems. Several studies have indicated that the thermal performance algorithms contained in the different programs produce similar results. However, little comparative analysis has been done of the economic algorithms in these programs. This report compares the economic evaluation models in five computer programs widely used for analyzing solar energy systems: F-CHART 3.0, F-CHART 4.0, SOLCOST, BLAST, and DOE-2. Differences in analysis techniques and assumptions among the programs are assessed for their consistency with the federal requirements for life-cycle costing (10 CFR Part 436), effect on predicted economic performance and optimal system size, ease of use, and general applicability to diverse system types and building types. The FEDSOL program developed by the National Bureau of Standards specifically to meet the federal life-cycle cost requirements serves as a basis for the comparison. Results of the study are illustrated in test cases of two different types of federally owned buildings: a single-family residence and a low-rise office building. The study indicated that none of the programs except FEDSOL fully conformed with the federal requirements for life-cycle cost analysis of renewable energy projects. However, with considerable manipulation of data inputs and simplification of assumptions, they could provide similar predictions for one measure of economic performance, net present value savings.

Fedsol :

“…Comparison of the SLR Method With Other Methods . When applied to standard residential systems for space and water heating, the SLR method can be expected to give similar predictions of solar performance on an annual basis to those obtained from F-CHART, the design method most widely used, and from SOLCOST [9,20,23].…”

“…SHW SYSTEMS (TYPES [1][2][3][4][5][6][7][8][9][10][11][12] Earlier versions of the SLR method and the initial version of the FEDSOL program expressed the monthly solar fraction of SHW (service hot water) systems as a function of the monthly SLR. The annual solar fraction was calculated from the results of the twelve monthly calculations.…”