Development of Various Photovoltaic‐Driven Water Electrolysis Technologies for Green Solar Hydrogen Generation

Abstract

Direct solar hydrogen generation via a combination of photovoltaics (PV) and water electrolysis can potentially ensure a sustainable energy supply while minimizing greenhouse emissions. The PECSYS project aims at demonstrating a solar‐driven electrochemical hydrogen generation system with an area >10 m2 with high efficiency and at reasonable cost. Thermally integrated PV electrolyzers (ECs) using thin‐film silicon, undoped, and silver‐doped Cu(In,Ga)Se2 and silicon heterojunction PV combined with alkaline electrolysis to form one unit are developed on a prototype level with solar collection areas in the range from 64 to 2600 cm2 with the solar‐to‐hydrogen (StH) efficiency ranging from ≈4 to 13%. Electrical direct coupling of PV modules to a proton exchange membrane EC to test the effects of bifaciality (730 cm2 solar collection area) and to study the long‐term operation under outdoor conditions (10 m2 collection area) is also investigated. In both cases, StH efficiencies exceeding 10% can be maintained over the test periods used. All the StH efficiencies reported are based on measured gas outflow using mass flow meters.

The annual-hydrogen-yield-climatic-response ratio: evaluating the real-life performance of integrated solar water splitting devices

“…Recent studies from the solar water splitting community highlight the efficiency gains caused by thermal coupling of the solar cells and the electrochemical component. 5,19,25,29 To the best of our knowledge, however, these efficiency gains were not evaluated for an outdoor-operating device exposed to changing weather conditions yet. To get a first impression, the AHYCR ratios for both locations were therefore also determined for a thermally decoupled device configuration.…”

“…32 The upscaling process for this greenhouse gas-free hydrogen production technology is currently dominated by electrolyzers powered with solar or wind energy. However, more integrated approaches such as photoelectrochemical (PEC) water splitting 28 or integrated photovoltaic-electrolysis systems 5,15 could optimize hydrogen production due to lower balance of system costs. For example, these systems are intended to work without the use of power electronics.…”

“…Integrated photovoltaic-electrolysis (PV-electrolysis) systems, in which the absorber is not directly immersed in the electrolyte exhibit a higher TRL due to better stability and more straightforward scalability. 5 A reason for the relatively low TRL of both approaches compared to the completely decoupled approach, however, is that these systems are intended to operate outdoors without a power inverter. While this on the one hand represents an advantage with respect to costs, maintenance, and efficiency (no losses in the inverter), it implies that these devices are exposed to varying weather conditions (e.g.…”

Dye‐sensitized solar cells as promising candidates for underwater photovoltaic applications

“…Solar photovoltaic (PV) technologies are widely known as one of the most environmentally sustainable 6 and safest means of generating electrical energy directly from sunlight 7,8 . The primary technological benefits of placing PV on or within water bodies include overcoming land use restrictions and cooling the PV that improves the power conversion efficiencies (PCE), 9 reduced racking costs, 10 and FPV can also decrease water evaporation, 11,12 which can be of particular use in arid regions 13,14 . Solar cells are the key components and building blocks in implementing PV systems.…”

“…7,8 The primary technological benefits of placing PV on or within water bodies include overcoming land use restrictions and cooling the PV that improves the power conversion efficiencies (PCE), 9 reduced racking costs, 10 and FPV can also decrease water evaporation, 11,12 which can be of particular use in arid regions. 13,14 Solar cells are the key components and building blocks in implementing PV systems. The majority of PV systems on the market are based on silicon technologies that have been optimized for AM1.5 1 sun conditions.…”