Thermodynamic solar energy conversion: reflections on the optimal solar concentration ratio
Résumé
We consider thermodynamic conversion of solar energy into electric energy in small
power units (less than 50 kWe). We present a very brief state-of-the-art review of the
available systems. Most current systems are based on the ‘Dish/Stirling’ technology,
which is very expensive. On the other hand, it is possible to produce mechanical energy
by means of very low temperature differential thermal engine using direct solar energy
without any concentration.
We present a very simple model, which shows that high solar energy concentration ratio
presents a limited interest, on the energetic point of view. Furthermore, an economic
assessment of a very low temperature 500We thermal engine proves that the conversion
of low temperature thermal energy into electricity has no economic interest. We conclude
that the most interesting systems should probably be based on a weak to medium solar
concentration ratio.