Enel, CEA achieve 24.47% efficiency in gallium-doped p-type heterojunction solar cell

Researchers at France's National Solar Energy Institute (INES) – an arm of the French Alternative Energies and Atomic Energy Commission (CEA) – and Italian renewable energy company and heterojunction solar module manufacturer Enel Green Power claim to have achieved a power conversion efficiency of 24.47% for a gallium-doped p-type heterojunction silicon solar cell.

The result was certified by the Institute for Solar Energy Research Hamelin (ISFH) in Germany. “It was achieved using the same manufacturing processes as the N-type, demonstrating once again the versatility and robustness of this technology,” the CEA said in a statement.

“A new way of manufacturing P-type Cz wafers has recently been deployed on a large scale by replacing boron doping with gallium (Ga) doping at no extra cost, making them insensitive to degradation phenomena under light,” according to the statement. “A recent study indicates that P-type heterojunction cells should have an efficiency gap of less than 0.4% absolute to be competitive with N-type heterojunctions.”

The solar cell also showed an open-circuit voltage of 749.2mV, a short-circuit current of 9823mA, and a fill factor of 82.05%.

The wafer technology for the device was provided by Chinese manufacturer Longi.

Enel Green Power and the CEA achieved in August 2020 an efficiency of 25.0% for a heterojunction solar cell with an active surface of 213 cm2, based on a M2 silicon wafer format. With this result, the two parties had improved upon their previous record of 24.63%, reached last February. Enel said at the time the increase in efficiency was made possible by combining busbarless technology – which enables more light to fall onto the cell surface – and a treatment developed by INES and Enel which further improved cell passivation