Uncertainty in economical analysis of solar water heating and photovoltaicsystems

This paper focuses on the statistical analysis of the energy fraction suppl ied by solar energy for solar water heating systems based on the f-chart me thod. An analysis is also presented for photovoltaic systems, where costs a re linearly proportional to collector area. The uncertainty of the solar fr action is correlated with the monthly means of the global irradiation and t he correlation coefficient between monthly means. Numerical examples for on e location in Brazil and three locations in the United States are presented . These examples show that the uncertainty of the life cycle savings is sig nificantly dependent on the uncertainty of the monthly means of the solar r adiation data. The present analysis intends to provide a basic procedure th at could be useful to make a straightforward feasibility analysis of a sola r system. This is particularly interesting to evaluate the investment risk associated with photovoltaic plants, for which the capital costs are compar able to the advantages in saving electric energy from the utility grid unde r present scenarios in most places. (C) 2001 Elsevier Science Ltd. All righ ts reserved.