Solar Panels and the Quest for $1/Watt

March 31st, 2008 by Michelle Bennett

If solar panels cost $1/watt, you can sell them (installation included) for $2/watt. Coal (installation included) costs $2.10/watt. To date, solar is still reaching to compete with coal, but the margins are closing. To (over)simplify how this works, you need to ignore issues like subsidies, qualitative costs, or kinks in the supply chain, and boil it down to money. Two hurtles that must be jumped before photo voltaic solar cells become cheaper than coal: efficiency and production cost. Fortunately the solar industry has already made important gains in both. Today, we’re going to talk about two types of solar panels: silicon and thin-film, and solar’s quest for $1/watt.

Silicon Solar Panels

Silicon panels are the most recognizable form of solar, in part because they’ve been around the longest. Unfortunately, until the end of 2007, they’ve always had some issues with cost. Popular Mechanic summarizes this much better than I could:

“Traditional solar cells require silicon, and silicon is an expensive commodity (exacerbated currently by a global silicon shortage). What’s more, says Peter Harrop, chairman of electronics consulting firm IDTechEx, “it has to be put on glass, so it’s heavy, dangerous, expensive to ship and expensive to install because it has to be mounted.” And up to 70 percent of the silicon gets wasted in the manufacturing process. That means even the cheapest solar panels cost about $3 per watt of energy they go on to produce. To compete with coal, that figure has to shrink to just $1 per watt.” – courtesy of Popular Science’s Michael Moyer

To clarify on that statement, the global silicon shortage has eased slightly, but supplies are still tight so the price of silicon is still relatively high. The bonus behind silicon solar panels is efficiency and lifespan. Silicon panels tend to be about 20%-27% efficient, reliable, and they last for over twenty years. That means with silicon panels you earn the cost of your investment back in the long term. Depending on where you live and what kinds of panels you buy, “long term” can mean 10-40 years. With cheaper solar panels, obviously, you would regain your investment sooner.

B.P. Solar offers a calculator to estimate your solar panel investment based on location, solar system, and home energy use. Just keep in mind that their calculator can’t adjust for fluctuating variables like energy costs, public policy, or B.P.’s competition; it’s a ball-park estimate at best. Divide the total cost by annual energy savings to calculate your return-investment time frame. (Mine was 35 years in an inefficient house)

In order to approach the magic $1/Watt goal, solar producers have tried new manufacturing techniques to reduce waste, boost efficiency, and lower prices. 1366 Technologies aims to come close to the $1/watt mark. They want to innovate manufacturing processes to reduce cost without sacrificing efficiency. With some investment money in their pocket, they’ll be working hard to bring their silicon panels to market in the future. Until then, or until more government support crops up, traditional solar panels are still best reserved for commercial (buy in bulk) and long-term investment.

Thin-film Solar Panels

These days thin-film technologies are all the rage in the solar industry. The benefit of thin-film solar technology is cost. By cutting the silicon out of the equation, companies remove a huge price barrier. One of the issues with thin-film technology is that it tends to be less efficient with a shorter lifespan. A new thin-film record was recently set at 19.9% efficient, which matches silicon panels. But unlike silicon solar, in this field the $1/Watt barrier has been successfully breached. Two companies can boast the achievement:

Nanosolar has already begun production of their famed solar product, which uses an innovative printing technology. They literally print the solar panels onto sheets of metal, like ink on paper. This technique allows for mass-production at an 80% reduction of manufacturing cost. They didn’t just reach the $1/watt mark, they surpassed it. Even the Department of Energy agrees: they compete with coal. For now, Nanosolar is sold out into the foreseeable future. In time we’ll no-doubt see their products become increasingly common as they diffuse through the solar market. So what’s the catch? Critics point out that the technology relies on indium, which has a finite supply. You can read some interviews, or watch a video for more information.

AVA Solar Inc. is another forerunner as they prepare to mass-produce their stream-lined solar panels. Their technique requires fewer raw materials, causes less waste, and maintains high efficiency–11%-13%. At under $1/watt, AVA Solar has nearly completed a production facility to mass-produce their technology. They promise “efficiency and stability performance comparable to the leading CdTe-based modules currently on the market” –CdTe is cadmium telluride, a popular thin-film composition. Kudos go out to Professor W.S. Sampath at Colorado State for helping to bring this technology to market.

The demand for either type of technology is high – and likely to keep rising. To draw from an example , Southern California Edison recently decided to invest in 65 million square feet of commercial roof space for solar panels. Check out these graphs for information spanning the past decade. Solar technology has entered the game with fossil fuels at a time when the technology has not yet reached its limits, as these recent innovations and improvements attest. Unfortunately, it will probably be years before solar starts to reach its full potential. Even without constrictions of silicon supply, building the production base will take time. When (not “if”) photo voltaic solar starts to compete with coal on a large scale, it will be interesting to see how the older, entrenched industry reacts. As oil falls out of favor, the coal industry sees an opportunity to expand, despite growing opposition to green house gases.

But let’s be fair; P.V. solar is not the silver bullet to clean energy. Even the most efficient, affordable solar panels or films can only operate under the sun, and they require batteries to store excess energy. That means P.V. solar works well during peak hours, when people are awake and using all their electric gadgets and appliances, but at night or in higher latitudes, more options are necessary. Other solar technologies like solar-thermal could pick up the slack. Solar thermal is experiencing its own revival, but all technologies come with their pros and cons.

So we turn to other energy sources: consider wind, geothermal, algae fuel, or wave power. Each has the fundamental benefit of using renewable resources–energy that will never run out. In contrast, what is the weakness of fossil fuels? Extraction of a finite resource with pollution as a byproduct, culminating in powerful contributions to climate change. Which limitation would you choose in a technology? Infinite or finite source? What byproduct would you bet on? Equality of cost is coming in the energy industry; for P.V. solar it is already here.

Extra Sources:

Solar Efficiency Graph via the Department of Energy.

Solarbuzz.com

Image courtesy of Flickr









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