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.