40% efficiency from solar panels – possible?

Solar power plants use photovoltaic cells whose efficiencies are currently in the 20-23% range.

In fact, there is even a theoretical upper limit of about 33.2% for the conventional “single-junction” solar cells – called the Shockley–Queisser limit.

So how can some reputed research organizations claim that they have been able to reach efficiencies of much higher than 40%, even around 45%?

It is possible because they are using not a single-junction solar cell, but a multi-junction solar cell in which there is more than one p-n junction (a critical component) made of different semiconductor materials.

As the number of p-n junctions increase, the maximum possible theoretical efficiency increases too.

For efficiencies as high as 40%, in addition to using multi-junction solar cells, it is also important to have the sunlight falling on the cells to be concentrated through the use of mirrors or lenses.

In summary, generating efficiencies much higher than 25% from conventional solar cells is very difficult. For solar cells to have efficiencies beyond 30%, different cell architectures, as well as additional equipment to concentrate sunlight, will need to be used.