Photovoltaic electrolyzer with solar panels, anion exchange membrane



Belgian researchers have designed a solar-powered electrolyzer that uses standard-sized, wide-area shingled silicon PV to split water. The system is said to be able to achieve 10% solar-hydrogen efficiency with electrolyzer current densities of about 60 mA cm-2.

“The novelty of our approach consists in utilizing a standard-sized large-area shingled silicon PV to produce a voltage above 1.23 V for water splitting, combined with low-cost anion-exchange water electrolysis, which combines the higher operating current densities of polymer electrolyte membrane (PEM) with low-cost alkaline electrolysis materials,” said researcher Nina Plankensteiner pv magazine.

The scientists presented their findings “Photovoltaic electrolyzer system Operates >50 mA cm−2 combining a large-area shingled silicon PV module with large-area nickel electrodes for low-cost Green H2 Generation”, which was published recently RRL sun. They explained that PV-ECs offer the highest level of technological readiness and the highest solar-to-hydrogen efficiency of any electrolysis technology.

“The photovoltaic technology of choice in PV-EC systems, which produce commercially affordable electricity with a stable 20-25 percent efficiency at 30-40 mA/cm2, are series-connected silicon solar cells that provide more than 1.23 V for water splitting,” said researcher Joachim John. “Over the next decade, silicon tandem assemblies with perovskite-capped cells may play an additional role as conversion efficiencies approach 30 percent.”

They described the proposed system as a “commercially relevant configuration”. They said the AEM electrolyzer has nanomesh electrodes with a huge surface area of ​​26 m2/cm3 made of soil-rich nickel, as researchers previously. reported.

“Serial rotation of silicon solar cells is a particularly attractive approach to solar water splitting because a sufficiently high voltage per normal cell area can be achieved,” they said, referring to shingle panels.

The modules are railless structures, and only a small part of the cells are not exposed to sunlight. The cells are densely connected to form a shingle, and the resulting strips are connected with conductive glue. A smaller number of busbars reduces shading losses.

The lab-scale single-cell electrolyzer developed by the academics has two 4-micrometer-thin high-surface-area nickel nanogrid electrodes. It also has six silicon heterojunction cells with 38.5 cm2 shingles cut from standard 15.6 cm2 x 15.6 cm2 cells.

“The cells were connected in series and cover a variable open-circuit voltage in the range of 0.7 V to 4.3 V, depending on the number of cells connected,” the researchers explained, noting that the average efficiency of the cells was about 20%. fill factor about 80%. “The current-voltage characteristics of the electrolyzer showed that 1.8 V to 2.2 V is required to match the electrolyzer current density between 20 and 100 mA/cm2. This minimum voltage requirement can be achieved by connecting three or four silicon cells in series.”

The PV-EC system tested under normal lighting conditions was able to produce hydrogen for about 20 hours and achieved 10% solar-hydrogen efficiency at electrolyzer current densities of about 60 mA cm.−2which the group described as the highest current density reported for PV-EC systems in the literature.

The efficiency between solar and hydrogen was determined by on-site monitoring of the most important system parameters, such as operating current, voltage and hydrogen gas flow. Determining this figure of merit accurately is important when comparing PV-EC systems with each other, the researchers said. They noted that longer stability measurements should be tested at high enough current densities to stress the system.

The researchers also performed a series of performance dynamic load tests with gradual and sudden power changes during half a year of solar radiation. They claim that the tests showed that changes in cell voltage are negligible and have very little effect on PV-EC operation and hydrogen production.

“The next steps towards commercialization of the presented PV-EC system are long-term outdoor stability testing together with a longer dynamic load measurement protocol,” they concluded.

David is a passionate writer and researcher who specializes in solar energy. He has a strong background in engineering and environmental science, which gives him a deep understanding of the science behind solar power and its benefits. David writes about the latest developments in solar technology and provides practical advice for homeowners and businesses who are interested in switching to solar.

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