The Future Cost of Solar Panels

Solar power used to be expensive.

The thought of a rooftop full of solar panels used to be so sci-fi, so utopian, so laughably idealistic. An experimental pipedream for those who could afford it; a whimsical indulgence of easy wealth and new-age guilt. Anything but practical.

Used to be.

Recent developments are promising to make pV more prole-friendly than ever, and more help is on the way. Creative legislation and policy measures at the municipal and state levels, such as property tax abatements, expanded net-metering policies and feed-in tariffs, are building incentive structures designed to blunt the daunting start-up costs associated with photovoltaic arrays. And greater technological efficiency coupled with an increase in the number of available panels at the supply end could turn solar into a veritable bargain.

MIT researcher Emmanuel Sachs has found a way - or more accurately, a couple of little ways - to increase the efficiency of multicrystalline silicon - a cheaper and less pure form of the material used to make pV panels - without increasing its price. Single-crystal panels, though pricier, are 20% more efficient on average.

One way utilizes an innovative process to create longer, thinner silver wires that transmit generated energy from the panel to the battery. These wires are more cost-effective because they take up less surface area on the panel and hence allow more light to be processed. They can also be placed closer together, allowing them to carry more current, and are made from a less expensive form of silver, thereby cutting raw material costs.

Another way places “mirrored surfaces” on the interconnect wires that collect current from these silver wires and link adjacent cells. These wide, flat wires can cut down on pV efficiency by shading the panel by as much as 5%. The mirrors allow light to be reflected back into the panel at a more acute angle, which causes the light to remain trapped in the panel for a longer period of time, leading to more efficient absorption and energy conversion.

These seemingly small steps in tandem would help to increase efficiency of multicrystalline panels by more than 20%, lowering the cost of their generated energy from $2.00 to $1.65 per watt, on par with single-crystal. Other small adjustments - more efficient coating, substituting copper for silver - could bring the cost down to $1.00 - coal-burning prices - within four years, according to Sachs.

And one other factor may help lower the price of photovoltaic panels further. According to the US Energy Information Administration, silicon itself will get significantly cheaper in coming years; so many people have been purchasing panels recently that supply is having trouble meeting demand, boosting prices to unprecedented levels. The price of solar-grade polysilicon rose by a factor of nearly 20 between 2004 and 2008 - from $24 per kg to $450; total global demand for silicon rose from 17 million to 28 million kgs between 2006 and 2007 alone. However, this global material shortage will soon be alleviated by the twenty-one new silicon manufacturing plants that came on-line in 2007, with more slated for production.   As the second-most abundant element in the earth’s crust, silicon should remain affordable once the necessary processing infrastructure is in place. And this lower material cost will likely spur further demand and investment. Not so pie-in-the-sky, after all.

Click here for more info on Sachs and his latest developments.

Sources: “Engineering Silicon Solar Cells to Make Photovoltaic Power Affordable”, Scientific American; “Solar Thermal and Photovoltaic Collector Manufacturing Activities 2006″, US Energy Information Administration; “Silicon Prices”, www.wikinvest.com; “Marketbuzz 2008: Annual World Solar Photovoltaic Industry Report”, Solarbuzz; “Silicon”, Wikipedia; 1366 Technologies website (1366tech.com)


Posted on Friday, August 8th, 2008 at 1:30 pm | Tagged in Energy, Energy Efficiency, Green Building, Photovoltaics, Renewables, Sustainability, Technology | posted by Bill

AddThis Social Bookmark Button   Print Print   Email Email