CONCEPTUAL DESIGN OF A PHOTOVOLTAIC SOLAR CENTRAL RECEIVER POWER SYSTEM (COGENERATION, SOLAR ENERGY, HELIOSTATS)

The technical and economic feasibility of combining photovoltaics with central receiver technology is evaluated in light of recent developments in high-efficiency, high-concentration ratio, point-contact, solar cells. Not only can the central receiver approach produce the necessary solar concentration, but it also simplifies the problem of cell cooling and enables cogeneration of heat and electricity.; Using a specially modified version of the University of Houston computer code for central receivers, a variety of power plant designs were investigated. Electrical and thermal outputs of plants sized between 2.5 MWe and 30 MWe were computed and cost estimates made. Under certain stated conditions, the optimum size for these plants was found to be in the range of 25 to 30 MWe. Capital costs on the order of {dollar}1.60 per peak watt were estimated with plant capacity factors slightly greater than 20%. The fraction of the capital cost associated with photovoltaics was found to be on the order of only one-tenth, so total costs are relatively insensitive to the price of the solar cells themselves.; The economic feasibility of these "photovoltaic central receivers" was evaluated with traditional levelized cost measures as well as from the point-of-view of private ownership with power sales to the utility grid. Under optimum conditions and with stated assumptions, the fraction of capital costs that might be recovered from first-year revenues was estimated to be on the order of 9% without thermal sales and as high as about 20% with cogeneration.; Since many utilities are summer peaking, and pay more for power during summer afternoons, the potential advantage of a heliostat field that is oriented about a southeast-to-northwest axis rather than the traditional north-south axis was evaluated. This new off-axis design delivers peak power in the afternoon but, with current utility buy-back rates, the added economic benefit of doing so was found to be only modest. A sensitivity analysis was performed to determine how rapidly the off-axis design advantage increases as utilities increase the differential price paid for peaking power.