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Working towards grid parity together with Photovoltech

Working towards grid parity together with Photovoltech

The subsidy programs for consumers investing in renewable energy are gradually being cut back. This makes it imperative for producers to speed up cost-efficiencies in order to reach 'grid parity': the turning point where the cost price for generating solar energy equals the cost of electricity generated through traditional means such as oil, coal, nuclear energy and gas.

Sputtering – a key phase in the manufacture of solar cells

The research team of Photovoltech, a manufacturer of photovoltaic cells based in Tienen (Belgium), is continuously searching for ways that both improve the output of the solar cells and also lower the costs of the production process to make these cells. With this goal in mind, they called on Bekaert in mid-2008 to introduce an alternative sputter technology.

One way to manufacture photovoltaic cells is starting with slices of silicon. This silicon slice, or ‘substrate’, goes through a series of treatments before becoming an active solar cell. One crucial step in obtaining cell efficiency is applying an anti-reflective layer. This layer includes silicon, nitrogen and hydrogen and allows cells to easily catch the rays of the sun. It also hides defects. ‘Sputtering’ is one of the technologies to apply this special covering layer. Silicon particles are ‘shot’ from the sputter target using a vacuum vaporization process. They are then deposited in a thin layer on the substrate. This gives the solar cell its characteristic blue color.

quote photovoltech

Stijn Janssens (left) process engineer at Photovoltech: "The introduction of Bekaert’s rotatable targets provided us with many benefits: the sputter process runs much more stably, allows for longer production cycles and results in a lower failure percentage."

Lower cost-of-ownership because of Bekaert rotatable sputter targets

In mid-2008, Photovoltech investigated whether it was possible to switch from high-purity flat silicon targets to rotatable targets. Bekaert is a market leader in rotatable sputter solutions and was able to quickly offer a solution with a short cost recovery time. It also allowed optimal integration in Photovoltech’s existing manufacturing process.

The solution was tested during 2008 and was made operational in 2009. With good results, because the switchover provided Photovoltech with significant cost advantages and increased efficiency. Rotatable targets are different from flat targets because they erode more evenly, allowing for the use of 85% of the target (in comparison: this is only 25% for flat targets). This significantly lengthens the life of the target – up to three times as long – and that is a benefit for Photovoltech because it means lower maintenance, given that the equipment has to be stopped for a few hours when replacing the targets. The switchover also significantly lowers Photovoltech’s energy costs because the rotatable targets work at a lower capacity. Finally the product quality also improves: since the introduction of the rotatable targets the number of sputter defects has been cut in half and cell efficiency has been more level.

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