The efficiency of PV solar cells is not only affected by the photovoltaic materials and manufacturing techniques used to produce them, but temperature can cause problems with even the most efficient panels. The efficiency of PVs has always been known to decrease with increases in temperature, so cooling is usually necessary for applications that involve high illumination such as found with concentrated sunlight.
But cold is another issue: In some cases, cold can improve the productivity of electrical systems including PV panels. With that in mind, there may be locations that solar developers of large-scale energy plants have over looked, according to the recent study: Effect of Temperature on PV Potential in the World.
According to researchers at Japan’s National Institute of Industrial Science & Technology, some of the coldest geographic locations on earth have some the greatest potential in the world for capturing solar energy using PVs. In a study published August 18, 2011, in the American Chemical Societyjournal Environmental Science & Technology, lead author Kotaro Kawajiri argues that solar developers need to take a hard look at very high, remote regions such as the Andes in South America and the Himalayas, as well as places such as Antarctica. Since it is not only colder in these places, the altitude allows for abundant direct sunlight so these areas could potentially be particularly well suited to convert sunlight to electricity.
Advantage of Cold
The solar potential of these frigid regions is considered very high because some types of PV cells can generate electricity more efficiently at cold temperatures. While all PV panels are exposed to high temperatures during the normal course of an operational day, traditional silicon wafer cells are affected by heat more than others. It is the heat from the sunlight’s solar radiation that degrades PV cells and their transparent enclosures faster than any other single environmental factor. Currently, it is the hot, arid areas soaked in sunshine like the American Southwest that have long been favored as the best solar sites. Even conditions found in the tropics have the potential to cause problems. But take away that environmental heat factor and PV cells do not experience any measurable degradation. Kotaro Kawajiri and colleagues feel it is reasonable to assume PVs will have a greater lifespan in colder climates.
Of course PV solar facilities include more than just panels, they include sophisticated electronic invertors and controllers. But again, for most electronics heat is a killer and cold is considered good. Since the electronics do not need to be exposed directly to the elements as is required for the PV panels, there is a consensus that such housed electronics would not be an issue.
Potential Mountain Sites
The results of the Japanese study come from a larger investigation of worldwide photovoltaic capacity, but makes note the effects of core temperatures previously not studied. The researchers note that the Himalayas, which include Mt. Everest, are especially important because of their central location with regards to countries like India and the People's Republic of China which both have the potential for huge future energy needs. China consumes the most energy worldwide, using an estimated 4,190 Terawatt-hours (TWh) of electricity alone in 2010 compared to 3,741 TWh by the United States. According to the study, covering only 4 percent of the high-potential Himalayas’ region of south Asia with approximately 12,000 square kilometers (7,460 square miles) of PV solar panels could generate nearly all of China’s electricity based on 2007 electricity consumption data.
And because countries like India and China have greater greenhouse gas outputs per electric power unit than most areas, using PV power could produce a huge modification to the changes in climate, according to the researchers.
Antarctica Airfields and Other Uses
PVs have long experienced the cold, being used in space travel applications, such as the Mars rovers, as well as at remote research facilities at the North and South Pole with little loss of efficiency despite the harsh temperatures. Consider this: The Martian rover Opportunity landed on the red planet nearly 8 years ago for a PV-powered mission that was to last only 90 days. Scientists are currently analyzing photos just received that Opportunity snapped of a crater ridge on October 23, 2011. One estimate has put the rover – and its PV panels – surviving the Martian cold at currently 31 times beyond the original design lifetime. That is a pretty good argument for the untapped potential of using PVs in colder regions here on Earth.
The Japanese study noted Antarctica as one of the good cold weather geographical locations for producing solar energy. Managing energy use is critical at the McMurdo Station in Antarctica where temperatures normally can dip below -50°F. For such locations, the researches predict smaller-scale applications. One good example of such small scale, niche PV application is the current work being done in the United States to de-ice frozen airfields. Engineers at the University of Arkansas are developing an anti-icing system for airport runways using a conventional PV system to supply energy through conductive concrete that would function as a surface overlay on runways. The PV-supplied power allows the runway surface to continually maintain temperatures above freezing and thus prevent accumulation of snow and ice.
To take advantage of the potential solar power in the regions of the Andes, Himalayas, and Antarctica could prove difficult because of the rugged terrain and the infrastructure that would be required to maintain such an operation.
While large-scale solar facilities would be expensive to install in such cold areas, it would not be that difficult an engineering feat. However, while some of these areas all have great solar potential, some have a much harsher climate and weather than others which results in heavy hail and strong winds – two factors that can easily damage PV panels in remote regions that would make repairs nearly impossibly during certain seasons.
On the other hand, the results of the study at Japan’s National Institute of Industrial Science & Technology makes a good case for establishing small scale solar power plants for rural residents with low populations. One example cited in the report is Antarctica. Though Antarctica has virtually no sunlight for much of the year and building a large PV operation would be a waste, smaller units with advanced energy storage technology might be a consideration.
If the Japanese study results in nothing else, it does re-enforce the often over looked applications for PVs in colder climates beyond what they are already being used for. And as PV panel prices continue to plunge, more of these applications that had been overlooked in the past due to financial constraints should start opening up. And that means more niche markets for panel manufacturers designing for cold weather applications.