Do Numbers Make Sense

Press Release

"The Fraunhofer Institute for Solar Energy Systems ISE, Soitec, CEA-Leti and the Helmholtz Center Berlin have jointly announced that they have achieved a new world record for the conversion of sunlight into electricity using a new solar cell structure with four solar subcells. Surpassing competition after only over three years of research, and entering the roadmap at world class level, a new record efficiency of 44.7% was measured at a concentration of 297 suns. This indicates that 44.7% of the solar spectrum's energy, from ultraviolet through to the infrared, is converted into electrical energy. This is a major step towards reducing further the costs of solar electricity and continues to pave the way to the 50% efficiency roadmap".

"These solar cells are used in concentrator photovoltaics (CPV), a technology which achieves more than twice the efficiency of conventional PV power plants in sun-rich locations. The terrestrial use of so-called III-V multi-junction solar cells, which originally came from space technology, has prevailed to realize highest efficiencies for the conversion of sunlight to electricity. In this multi-junction solar cell, several cells made out of different III-V semiconductor materials are stacked on top of each other. The single subcells absorb different wavelength ranges of the solar spectrum".

A Closer Look at the Numebrs

Let us now try to validate the numbers given above.

Power is the product of voltage and current.

P_ideal=V_oc I_sc=(4.165)(0.1921)=0.8001Watts

P_max=P_ideal*FF=(0.8001)(0.8650)=0.6921Watts

This is the power produced by 5.20mm² of solar cell.

1mm² of solar cell would produce 0.1331Watts.

1m² of solar cell would produce 133.1kW of solar energy.

This is the power generated due to 297.3 suns.

A single sun would produce 133.1kW/297.3=447.67Watts of power.

This gives us an efficiency of 447.67/1000=0.4477=44.77%.