The Institute for Photovoltaics (E-I1), part of the Helmholtz-Zentrum Berlin (HZB), has developed a new solar cell in cooperation with the Institute for Solar Energy Research in Hameln (ISFH). The development, part of a project initiated by the federal ministry for environment and supported by Bosch, Schott Solar, Sunways and Stiebel Electron, has resulted in a solar cell that has yielded lab efficiency of 20.2%.
In 2011, results published showed that the cells had achieved efficiency in the range of 15–16%. However, a recent study conducted by the independent calibrating laboratory of the Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg measured an efficiency of 20.2%.
The solar cell concept employs two different photovoltaic technologies, back contacts and silicon-hetero contacts. While back contacts help to avoid what are commonly known as ‘clouding effects’, silicon hetero contacts use two semiconductors with different band gaps in one solar cell.
“Both methods have the advantage that they are already industrially used,” says head of the HZB-Institute Prof. Dr. Bernd Rech. “The combination of both concepts is a possibility to reach efficiency around 25%.”