Solar energy scientists from all over the world gathered to discuss alternatives to silicon-based solar panels during the international scientific conference that was held in Tallinn last week.

The solutions currently being developed in laboratories could make it possible to produce electricity from the sun cheaper in the future and also save natural resources.

Nikolai Spalatu, senior research fellow at the Tallinn University of Technology (TalTech), said that thin-film panels will have to replace silicon-based panels in order for solar energy to become more widespread. These are also easier to apply to a variety of surfaces and devices.

"To scale up and increase the efficiency of solar panel production, it is necessary to introduce new materials that can be produced more easily and affordably. Existing silicon panels are relatively simple. However, their production is complicated, resource-intensive, and time-consuming. The 100-nanometer-thick thin-film panels can be manufactured substantially faster and with far less material," Spalatu told ERR.

Also, he said the efficacy of silicon panels decreases as the temperature increases. "In high temperatures, silicon panels perform poorly." Similarly, they store more heat, which is detrimental to the solar panel's cells. Alternatively, he explained, thin-film panels have less material to retain heat, making them more effective in humid environments.

Land use, Spalatu went on to say, is yet another crucial factor. Large solar parks require a considerable amount of land. "People want to use it for different purposes, such as agriculture," he said. However, thin-filmed solar panels could cover as much land as necessary, as the material is translucent, he explained.

However, according to the researcher, also the current silicon technology still has space for growth and could see additional investment. "Technology based on silicon is already 60 years old. Developing any technology takes time and to mature, emerging technologies require both time and money," Spalatu said.

Technology still has room for improvement

According to Mattias Kaiv, a spokeswoman for Eesti Energia, the development of thin-film solar panels has gotten a lot of interest because they are appropriate for extremely specialized applications. "The advantage of this technology is its light weight; 50-100 times less material is required to produce the same amount of energy as conventional solar panels," he said.

The main downside of thin-film solar panels, according to Kaiv, is their short lifespan. They have a lifespan of five to 15 years, depending on the manufacturer, and are easily damaged. "The primary reason they are not widely used in large-scale energy production is that they are still expensive to maintain," he explained.

Also, the benefits of thin-film solar panels have yet to be realized in mainstream applications. "If a private home or apartment building wants to produce locally, the simplest and most cost-effective solution is to install solar panels on the roof. Thin-film cells are advantageous, however, if there is a desire to produce multi-functional devices, such as high-rise window panes that generate energy while shielding against solar intensity," Kaiv said.

"Their implementation, however, needs exceptional coordination among customers, building material manufacturers and technology makers, which is likely the most significant barrier to their implementation at the moment. In the construction industry, the goal is to use solutions with a lifespan of at least 15 years and minimal maintenance requirements."

According to Kaiv, new solar technology has a great deal of potential. However, the optimal use cases must be identified and implemented in order to develop consumer trust.

Tandem solar panels

According to Professor Philip Dale of the University of Luxembourg, innovation in silicon-based solar panel production is also likely. Solar panels are now stacked in a single layer. This means that the solar cell stores all of the energy and converts it into electricity. Dale told ERR that in the future, two panels will be placed on top of one another.

"This means that they work on different matters, so to speak: the top panel will be designed to make the most efficient use of high-energy-intensity, or blue, light; lower intensity light will pass through the top panel and be received by the bottom panel, whose elements are designed to make efficient use of that light; and thus, greater overall efficiency can be achieved, meaning that more solar energy is converted into electricity," Dale explained.

"Conventional solar panels currently have an efficiency of about 22 percent. Tandem panels have exhibited efficiency of 30 to 30 percent in the lab, so it would be great if we could increase their field efficiency to 28 percent," the physicist said.

However, Dale also emphasized that in order to make better use of solar energy, thin-film panels, in addition to silicon-based panels, have to be widely adopted. "Silicon-based panels require three to four times as many resources to produce as thin-film ones. The carbon footprint of manufacturing silicon panels is three to four times greater," he said.

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