Energy Efficiency
Improving the efficiency of solar panels can lower costs and allow the production process to go farther.
Improving the efficiency of solar panels can lower costs and allow the production process to go farther.
Bandgap Engineering, a privately held startup company based in Woburn, Massachusetts, intend to create solar cells with twice the electrical output of conventional solar cells. This feat will be achieved by using tiny nanowires that increase the amount of solar energy a cell is capable of absorbing.
These nanowires “trap” sunlight; similarly to how anti-reflecting coating and algae shells are able to enhance the electrical output of solar cells.
The picture to the left was taken through an electron microscope. You can see the nanowires on the right hand side. Photons enter these structures, and bounce around like if they were in a pinball machine, which significantly increases their potential to free electrons and generate current. Another way of putting it is that the nanowires reduce reflection and increase absorption – critical factors for all solar cells. Solar cells enhanced with nanowires are in fact capable of reflecting less than 1 percent of incoming light, which is 5-8 times better than the best anti-reflective (AR) coatings and surface textures.
A conversion rating of 60% is the maximum theoretical potential of solar cells enhanced with these nanowires. In other words, more than half the amount of the solar energy that comes in is successfully converted into electrical current. Bandgap Engineering has set a practical target of 38%, which is about the double of the best solar cells on the market today.
Another result of a solar cell enhanced with Bandgap`s nanowires is a broader absorption spectrum. This means the solar cells have better efficiency during ambient light conditions –in the morning, afternoon or on overcast days – which ultimately increase the overall performance.
Richard Chleboski, the CEO of Bandgap Engineering, has stated that they already are able to create solar cells that operate at around 20% in cell efficiency, about the same as the best performing solar modules on the residential market today.
The technology that is required to develop these nanowires already exists on the market, which simplifies the development processes and brings down costs. According to Chleboski, the solar panels made out of the company`s solar cells will only cost $1 per watt – significantly less than the cost of modern solar panels.
Investors include New Enterprise Associates (NEA), Sumitomo Corporation and the Massachusetts Green Energy Fund. Bandgap Engineering received $7.4 million in funding from those investors in 2008 and 2009. The company was also awarded a $750,000 “Next Generation PV” grant from the Department of Energy in 2011.
Bandgap Engineering has made bold claims, and if they indeed are able to pull them off, the solar industry could be left changed forever. It`s still a bit early to make predictions – every week, press releases on new “revolutionary” solar cell technologies that supposedly cut the cost of solar panels in half are published.
On the other hand, the costs of solar panels have decreased significantly over the last decade or so – at least partially thanks to technological innovation.
It will be interesting to follow Bandgap Engineering in the next couple of months, as they get closer to getting their technology on the market.
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