Astrowatt has developed a new manufacturing method for solar cells that would permit the relatively high efficiency of traditional silicon wafer solar cells, but while wasting far less silicon in the process. This could lower the cost of solar power.
First, i’ll help you to understand the two main types of solar cells
You may have already heard of thin-film solar cells. Thin-film cells are literally printed using an inkjet printer onto a substrate (surface) that can be glass or plastic, and it may be encased in a protective solar panel. The ink used is a semiconductor material such as CIGS, cadmium telluride, and even some silicon types.
This type of solar cell can be flexible, while traditional silicon wafer solar cells are not.
A solar cell is the electricity generating part of a solar panel. A solar panel is a group of interconnected solar cells in a case made of a combination of metal and glass or plastic.
The Astrowatt manufacturing process is not thin-film, even though it sounds like it. The most traditional solar cell manufacturing technique involves sawing brittle wafers of silicon into smaller pieces to make cells, and during this process, nearly half of the silicon wafer is wasted as sawdust.
Of course, the cost of the tremendous material wastage is included in the price of the solar panels, and this is an important reason why solar panels are expensive.
Astrowatt has actually manufactured solar cells by peeling thin layers of silicon off thick silicon wafers.
The traditional sawing process yields three solar cells from every 1 millimetre thick wafer of silicon (solar cells are extremely thin), but the new method yields five or more cells per wafer and hence eliminates most of the silicon wastage.
The Manufacturing Process
Astrowatt’s manufacturing process is commenced by sawing blocks of silicon into wafers that are each 1 millimetre thick. Then the top of each wafer is modified so that it can act as the back of solar cells, and this process is ended by depositing a layer of metal onto the wafer.
Next, the wafer is heated. Heating causes stress within the material because the metal and silicon expand at different rates. In case you didn’t know, heating causes materials in general to expand (become less dense and get bigger).
A wedge is then applied to the edge of the stressed silicon which causes a crack that extends to the other edge.
This allows the manufacturers to peel away the metal film mentioned above with a 25 micrometre thick layer of silicon, and they continue to peel off 25 micrometre thick layers until they are left with a thick silicon wafer that is still of high enough quality to put back in the furnace to recycle into another block, unlike sawdust.
Finally, the 25 micrometre thick metal-silicon layer is processed to produce a complete solar cell.
Source: Technology Review