Green Energy Technology: String Ribbon Silicon Wafers

Another step forward in the field of green energy technology is the production of very thin silicon films for solar cells. Some thin film solar cells use vapour deposition, some use amorphous silicon; but both these techniques result in cells that have lower efficiency than for crystalline silicon cells.

The string ribbon technology overcomes this problem by using a pair of wires drawn through a tub of molten silicon. A film forms between the wires, just like a film of soapy liquid forms on a child's bubble blower. The wires are drawn through the molten silicon continuously, resulting in a thin layer of crystalline silicon.

The solid silicon formed during this process is multicrystalline. This means it is not as efficient at converting sunshine into electric current as monocrystalline cells, but better than amorphous silicon. The process is highly efficient both in terms of energy consumption and the amount of silicon used. It also eliminates the waste associated with cutting wafers of silicon from ingots as has previously been used to make silicon solar cells.

Here is a video of the manufacturing process. You can see that each mini furnace produces two two metre ribbons in half an hour. These are then cut for use in solar panels.

Efficiency Rates

The cells produced from this process have an efficiency upwards of 15%, which is excellent. Combine this with the inevitable decrease in cost of panels that this technology will allow and this method of manufacture is clearly a big step forward for green energy.