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Kombinierter Wirkungsgrad von PV-Konzentratorzelle und Wärmekraftmaschine

 
: Goetzberger, A.; Wettling, W.

Deutsche Gesellschaft für Sonnenenergie e.V. -DGS-, München:
7. Internationales Sonnenforum 1990. Tagungsbericht. Rationelle Energieverwendung und Nutzung erneuerbarer Energiequellen im regionalen und kommunalen Bereich. Bd.2
München: DGS-Sonnenenergie-Verlags GmbH, 1990
S.1335-1340
Internationales Sonnenforum <7, 1990, Frankfurt>
Deutsch
Konferenzbeitrag
Fraunhofer ISE ()

Abstract
The excess heat of a photovoltaic concentrator cell can be used to drive a thermal power engine (as e.g. a Stirling motor) such that the thermal engine is an active cooling device for the solar cell. The efficiency of the solar cell decreases with increasing temperature T, whereas the efficiency of the thermal engine increases with T. The combined efficiency of a solar cell coupled to a thermal engine, Eta, was calculated as a function of the bandgap energy of the solar cell, Eg, and of T. The efficiency of the thermal engine was assumed to be one half of that of a Carnot engine. For solar cells the present state of the art is taken into consideration. The maximum of the combined efficiency is found in the range of Eg = 1.3 to 2 eV depending on T. The efficiency lies between 35 and 40 % for a concentration factor of sunlight C = 1000. For GaAs solar cells (Eg = 1.42 eV) a broad maximum of the combined efficiency is found at T between 200 and 500 degree C with eta = 39 % for C = 1000. I n the temperature range around 250 degree C the solar cell and the thermal engine contribute each about half to the total efficiency.

: http://publica.fraunhofer.de/dokumente/PX-20639.html