Cost reductions and the expansion of production capacity throughout the world has been opening up completely new possibilities for PV in recent years. They make the technology “a game changer of the global energy system”, as scientists from the Fraunhofer Institute for Solar Energy Systems ISE have argued. But development is creating more opportunities while also increasing the number of challenges the industry faces, according to a recent paper in the journal Science by the Global Alliance for Solar Energy Research Institute (GA-SERI).
The growth of the PV industry to a multi-terawatt market is proceeding faster than expected, according to industry experts. At the end of last year, 500 GW of solar had already been installed worldwide. By 2030, researchers expect 10 TW globally and 30 to 70 TW by 2050.
“The cost of PV modules has dropped by two orders of magnitude over the last 40 years and by the end of 2018, it was below $0.25 per watt*,” said Andreas Bett, head of Fraunhofer ISE. With these costs, solar power is “absolutely competitive” in many parts of the world. At the same time, changes in the generation and transmission system will occur due to the increasing share of PV in the electricity mix. “The fundamental change in our energy system challenges us to develop complementary technologies such as storage and drive sector interconnection,” Bett said.
In the paper, the researchers identify a total of five fields of action. The first is “Grid and Power Electronics”. Here, the focus is on harmonizing consumption and production, even over longer distances. Photovoltaic systems will increasingly have to take on grid-related services such as voltage regulation and frequency control. New-generation inverters have been developed just for this purpose. But new technologies such as virtual vibration controllers have also created robust, reliable photovoltaic systems, the researchers said.
The second area of action is storage. The price of lithium-ion batteries has dropped by 80% over the past eight years. In view of capacity expansion and technology development, further reductions are to be expected in the future. In addition, scientists are currently working on alternatives from cheaper materials with higher energy density. The scientists see pumped storage power plants as another option with considerable technical potential.
The third field of action that international researchers have recognized is sector coupling. In order to electrify the transport sector and the building heating systems, the use of renewable energy will have to be increased considerably in the future. In addition to heat pumps and an increase in energy efficiency, hydrogen and ammonia will also play an important role. The latter could help to reduce emissions from steel, iron and fertilizer production processes.
The fourth field of action is Power-to-X and Power-to-Gas. Low-cost solar and wind power could be used to generate hydrogen, methane and other hydrocarbon compounds, which could then be used as feedstock for the chemical industry. With power-to-X technologies, many terawatt-hours of wind and PV could be captured and stored for long periods of time. At the same time, scientists in the power-to-X sector still see a lot of potential to increase efficiency and cut costs.
The fifth field of action deals with “research and production”. In the last 40 years, there has been a reduction in module costs of 23% per doubling of installed capacity. This trend will continue, according to the researchers. In the case of crystalline PV, the trend is currently toward low-cost solar cells with passivated contacts, which make higher efficiencies possible. Even in the thin-film area, technological advances in recent years have now enabled efficiencies of more than 20%. For multijunction solar cells based on silicon, the efficiency potential is more than 35%, said the scientists. In terms of production, the increased volumes could lead to new research and development tasks. Here, questions about material supply, sustainability and recycling are more in focus.
In addition to Fraunhofer ISE, researchers from Japan's National Institute of Advanced Industrial Science and Technology (AIST) and the National Renewable Energy Laboratory (NREL) are also members of GA-SERI. Since 2016, this group of international experts has regularly discussed the challenges facing PV technology.
* The article was amended on June 4, 2019, at 11.30 am to amend the cost of PV modules, which had dropped below $o.25 per watt, not $25 per watt as previously reported. Apologies for the discrepancy.
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