IMEC, a Belgian institute renowned for microelectronics research, have produced an industrially‑sized 21.5% efficient n‑type solar cell. This result represents the highest efficiency achieved for cells of its kind and is another step towards greater adoption of n-type solar cells.
N-type solar cells improve on the current state-of-the-art by allowing for better overall material quality (in the form of lower charge losses in the bulk of the n-type silicon) and are not prone to the long term performance degradation mechanisms that can affect p-type solar cells.
The ‘type’ refers to the dominant electric charge of the base material and in the case of n‑type silicon the dominant charge is negative; ‘n’ for negative and ‘p’ for positive. Most solar cells we see installed on Aussie roofs are based on p-type silicon.
The metal contacts on the front surface of the Imec cell are formed using metal plating, which can allow for quite narrow features and consequently reduce shading. The cell also employs an advanced solar cell structure, referred to as a ‘PERT’ (Passivated Emitter, Rear Totally diffused) cell, which is designed to eliminate performance issues that arise when electroplating metal onto the front surface.
Commenting on its performance benefits, Jef Poortmans, Scientific Director of Photovoltaics at IMEC, stated: “We think that [our n-type cell] has an efficiency potential between 22 and 23%. So let’s say, roughly speaking, with n-type silicon you gain about 1% over p‑type.”
N-type technology promises the benefits of superior long term energy production and performance. Over the lifetime of a PV system, lower solar cell material degradation equates to a reduction in the cost of producing each watt-hour of electricity. Simply put, more stable and efficient cells such as these will save PV consumers even more money.
Predictions of when n-type solar cells are set to dominate the PV market vary considerably, as the wider implementation of n-type material hinges upon the ability of cell producers to source cheaper n‑type wafers.
However, most commentators seem to indicate that n-type material is a near‑term technology that offers a way forward for cell efficiency and reliability. N-type solar cells have a sunny future ahead and are set to take a much larger share of the PV market in years to come.
Top Image Credit: IMEC
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