A Solar Cell Solution?

Climate change has become an increasingly large concern among scientists and the general population. Many scientists agree that this crisis must be addressed and fixed within the next half century or it may become an irreversible process. Billions of dollars have been spent to address this issue and develop alternative energy sources. While no energy is entirely 'clean', solar energy provides the most environmentally friendly alternative energy.

However, the primary concern is that up to this point, solar cell technology has failed to be implemented on the large scale required to make any sort of appreciable environmental impact. According to the Institute for Energy Research, solar energy makes up less than 1% of the total energy consumption in the U.S. In order to ameliorate the burden we are placing on the Earth's atmosphere, it is imperative that we find a way to increase the amount of solar energy produced. To do this, there needs to be a viable option, in terms of cost and efficiency. The good news is we might have developed a viable option: Copper-Indium-Gallium-Selenide thin-filmed solar cells (CIGS).

Figure 1. Flexible CIGS solar cells are lightweight and easy to install.

Traditional silicon solar cells have dominated the photovoltaic market in the past and currently controls ~90% of the current market, and has a relatively high efficiency of around 25%, according to the National Renewable Energy Laboratory (NREL). So what's the drawback? In the words of Mark Pinto, Applied Material's executive vice president for energy and environmental solutions, "with solar, it's all about cost."

Cost is the primary reason why silicon solar cells has failed. Their high cost has rendered them an ineffectual option for a major alternative energy source. Cost is also an issue with the most efficient solar cells, such as the multi-junction solar cells, which offer the 46% efficiency (via NREL). Because the cost of these solar cells are so high, there is little to no incentive for producers to produce these cells in large quantities, thus solar energy use in the United States is almost negligible. The failure of the silicon solar cell comes at the cost of the Earth's environment.

CIGS is very different from the silicon cells. They belong to a group of solar cells, which utilize new thin-film technology. One advantage of these thin-film cells is that they are flexible and are thus easier to install. Oppositely, silicon solar cells are rigid and require a much stronger substrate (i.e. roof) to attach it to. Additionally, CIGS is significantly cheaper to produce mostly because it can be produced in a one step process.

Figure 2. Thin-film solar cells are diverse due to their flexibility. Here they are shown laid over roof shingles via Paul Martin.

Previously, the primary concern with CIGS was its relatively low efficiency. However, recent advances in solar technology has increased the efficiency of CIGS up to 16-23% (PVinsights and NREL), which is remarkably close to the silicon solar cells. As a result of the relatively low cost of CIGS and its steadily increasing efficiency, Brad Mattson, CEO of Siva Power explains that CIGS offers the "holy grail in solar: silicon-like efficiencies at low thin-film costs". Therefore, CIGS offers what no other solar cell currently offers.

It is imperative that we continue to develop CIGS technology in order to implement it on a large scale. By doing so, we will be able reduce environmentally harmful emissions and, consequently, start to improve our current climate crisis. With steady increases in CIGS efficiency and cost over the past decade, this solar cell solution may become a reality sooner than we think.