Thin film solar companies are dropping like flies. This year, companies such as Abound and Konarka have gone bankrupt and things do not look like they are going to get much better. Crystalline panel prices continue to drop dramatically and European subsidies are at risk. Despite these obstacles, does thin film have a future in the solar industry? Should projects use thin film panels? There is no obvious answer to this question. A lot of environmental factors go into the performance of solar cells. In certain situations each technology has an upper hand. In the end, it all comes down to the cost per watt.
Technology
To better understand the solar industry's situation, we first need to look at some general theory behind photovoltaic panel technology. PV performance depends on cloud cover, temperature, ground albedo, wind speed and much more. While doing some research last week I ran into the following (very basic) equation:
P = Pr (1 + (25-T)(C))(Si /1000)
where P is the output, Pr is the rated output at STC, T is ambient temperature, C is the thermal coefficient and Si is solar insolation
From this relationship we can extract some basic truths about solar panels. Low temperatures and high solar insolation increase power output. Meanwhile the more negative the constant C, the more sensitive to temperature the panel will be. Unfortunately, the equation does not give us the whole picture. There is no way to see how absorption spectra or wind speed affect performance.
From a purely technical perspective, thin film has several advantages over other solar technologues. One of the main differences between the two major solar panel types is their thermal coefficient (C). Thin film has a much smaller value for C, meaning that its performance changes much less in response to temperature. Therefore, we can say that when building a solar plant in the desert, this technology is going to have an edge. Absorption is another key a factor in this debate. Thin film cells absorb a wider range of light, absorbing more infrared (IR) and ultraviolet (UV). The cells achieve this by combining several layers of materials with different absorption spectra. Together, the layers can absorb more light than the crystalline cell. This gives them the advantage if an area doesn't have consistent sunshine. Just because it is cloudy outside does not mean there is no IR or UV light to be harnessed! Finally they can also be "rolled" during manufacturing, which is a very efficient process, and do not need mounting for installation.
Overall thin film panels are more reliable than crystalline, performing consistently under poor weather conditions and high temperatures. However, technology is not the deciding factor when deciding to install a solar panel. Economics has the last laugh.
Implementation
Projects limitations and costs play an important role in designing a solar electricity system. Thin film can only be used if there is enough space. A simple calculation based on panel efficiencies will show that nearly twice as much space would be needed for thin film. The extra land costs alone may be enough to kill any thoughts of using the less efficient panels in some projects. An interesting point to this argument can be made for off-grid facilities. Since thin film is capable of producing electricity in bad conditions, the technology may reduce the required battery bank size. This will decrease the investment and the space needed. If you can still produce some electricity on rainy days, all of a sudden you don't need as much storage. In general the capability to produce electricity in poor conditions is crucial in large projects.
Another practical factor to consider is racking. Thin film panels do not need special racking that is necessary for crystalline installations. They can be attached directly to roofs and other smooth surfaces using an adhesive. This brings down their installation cost and gives engineers and architects more freedom in choosing a site or surface for solar panels.
From all the information above, you may assume that thin film panels are the cheapest on the market. Unfortunately this is false. Silicon prices are so low that despite the theoretical advantage of this technology, crystalline panels dominate the market. Thin film producers need to decrease costs to stay competitive. There are two main ways to this: expand manufacturing capacity or improve technology. Both are very costly initiatives that could get companies in debt. R&D and new factories are not free. Many solar companies have tried these strategies. Abound stopped production during the first quarter in order to focus on research and development, only to go bankrupt recently. Meanwhile, LDK Solar is $3.4 billion in debt.
Theoretically, if a site has good year round insolation and reasonable average temperature, crystalline is the logical choice. If the site is large, hot or cloudy and there are intermittency concerns, thin film now looks like a more reasonable option. You can think about it like this: thin film will be better suited in deserts and northern regions while crystalline will perform well in between the two extremes (unfortunately thin film will have to compete with solar thermal in deserts). While there is clearly potential for both technologies, the thin film industry is going to have to somehow reduce its cost to compete with crystalline panels. It is still too early to call, but there is still a promising future for thin film solar panels.
Technology
To better understand the solar industry's situation, we first need to look at some general theory behind photovoltaic panel technology. PV performance depends on cloud cover, temperature, ground albedo, wind speed and much more. While doing some research last week I ran into the following (very basic) equation:
P = Pr (1 + (25-T)(C))(Si /1000)
where P is the output, Pr is the rated output at STC, T is ambient temperature, C is the thermal coefficient and Si is solar insolation
From this relationship we can extract some basic truths about solar panels. Low temperatures and high solar insolation increase power output. Meanwhile the more negative the constant C, the more sensitive to temperature the panel will be. Unfortunately, the equation does not give us the whole picture. There is no way to see how absorption spectra or wind speed affect performance.
From a purely technical perspective, thin film has several advantages over other solar technologues. One of the main differences between the two major solar panel types is their thermal coefficient (C). Thin film has a much smaller value for C, meaning that its performance changes much less in response to temperature. Therefore, we can say that when building a solar plant in the desert, this technology is going to have an edge. Absorption is another key a factor in this debate. Thin film cells absorb a wider range of light, absorbing more infrared (IR) and ultraviolet (UV). The cells achieve this by combining several layers of materials with different absorption spectra. Together, the layers can absorb more light than the crystalline cell. This gives them the advantage if an area doesn't have consistent sunshine. Just because it is cloudy outside does not mean there is no IR or UV light to be harnessed! Finally they can also be "rolled" during manufacturing, which is a very efficient process, and do not need mounting for installation.
Overall thin film panels are more reliable than crystalline, performing consistently under poor weather conditions and high temperatures. However, technology is not the deciding factor when deciding to install a solar panel. Economics has the last laugh.
Implementation
Projects limitations and costs play an important role in designing a solar electricity system. Thin film can only be used if there is enough space. A simple calculation based on panel efficiencies will show that nearly twice as much space would be needed for thin film. The extra land costs alone may be enough to kill any thoughts of using the less efficient panels in some projects. An interesting point to this argument can be made for off-grid facilities. Since thin film is capable of producing electricity in bad conditions, the technology may reduce the required battery bank size. This will decrease the investment and the space needed. If you can still produce some electricity on rainy days, all of a sudden you don't need as much storage. In general the capability to produce electricity in poor conditions is crucial in large projects.
Another practical factor to consider is racking. Thin film panels do not need special racking that is necessary for crystalline installations. They can be attached directly to roofs and other smooth surfaces using an adhesive. This brings down their installation cost and gives engineers and architects more freedom in choosing a site or surface for solar panels.
From all the information above, you may assume that thin film panels are the cheapest on the market. Unfortunately this is false. Silicon prices are so low that despite the theoretical advantage of this technology, crystalline panels dominate the market. Thin film producers need to decrease costs to stay competitive. There are two main ways to this: expand manufacturing capacity or improve technology. Both are very costly initiatives that could get companies in debt. R&D and new factories are not free. Many solar companies have tried these strategies. Abound stopped production during the first quarter in order to focus on research and development, only to go bankrupt recently. Meanwhile, LDK Solar is $3.4 billion in debt.
Theoretically, if a site has good year round insolation and reasonable average temperature, crystalline is the logical choice. If the site is large, hot or cloudy and there are intermittency concerns, thin film now looks like a more reasonable option. You can think about it like this: thin film will be better suited in deserts and northern regions while crystalline will perform well in between the two extremes (unfortunately thin film will have to compete with solar thermal in deserts). While there is clearly potential for both technologies, the thin film industry is going to have to somehow reduce its cost to compete with crystalline panels. It is still too early to call, but there is still a promising future for thin film solar panels.
More information on solar technology can be found at http://www.solartown.com, where I currently publish news and learning articles. This website offers crucial advice to those homeowners who are transitioning to solar power. For up-to-date news on the solar industry, or interesting material on solar power, visit our website!
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