Comparative study of the performances of four photovoltaic/thermal solar air collectors

An extensive investigation of the thermal, electrical, hydraulic and overal l performances of flat plate photovoltaic:thermal (PV/T) air collectors has been made. Four popular designs are considered with the air flowing either over the absorber (Model I) or under it (Model II) and on both sides of th e absorber in a single pass (Model III) or in a double pass fashion (Model IV). Heat balance equations are written for each model and are numerically solved, incorporating measured climate data. The effects of air specific fl ow rate and the selectivity of the absorber plate and PV cells on the perfo rmances have been examined. It is found that under similar operational cond itions, the Model I collector has the lowest performance, while the other m odels exhibit comparable thermal and electrical output gains. Nevertheless, the Model III collector demands the least fan power, followed by Models IV and II. It is also shown that selective properties are inappropriate for t hese PV/T collectors due to the resultant reduction in the generated PV ene rgy, especially at low flow rates. The study provides valuable information regarding the design and operation of such types of PV/T air collectors. (C ) 2000 Elsevier Science Ltd. All rights reserved.