Converting sunlight to electricity with solar cells has an efficiency of 15%. It's possible to achieve a

Question:

Converting sunlight to electricity with solar cells has an efficiency of ≈15%. It's possible to achieve a higher efficiency. (though currently at higher cost) by using concentrated sunlight as the hot reservoir of a heat engine. Each dish in Figure P11.30 concentrates sunlight on one side of a heat engine, producing a hot-reservoir temperature of 650°C. The cold reservoir, ambient air, is approximately 30°C. The actual working efficiency of this device is ≈30%. What is the theoretical maximum efficiency?

FIGURE P11.30