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@ARTICLE{Chibuko:1041457,
      author       = {Chibuko, Uchechi and Merdzhanova, Tsvetelina and Agbo,
                      Solomon and Rau, Uwe and Wurstbauer, Ursula and Astakhov,
                      Oleksandr},
      title        = {{B}reaking limits of solar-to-hydrogen efficiency via
                      synergy with batteries},
      journal      = {International journal of hydrogen energy},
      volume       = {127},
      issn         = {0360-3199},
      address      = {New York, NY [u.a.]},
      publisher    = {Elsevier},
      reportid     = {FZJ-2025-02257},
      pages        = {38 - 50},
      year         = {2025},
      abstract     = {Coupling of photovoltaics (PV) with electrochemical (EC)
                      water splitting is an established concept for storage of
                      excess PV energy via production of green hydrogen. However,
                      intermittent PV output presents a challenge for the
                      stability and lifetime of EC devices in both direct coupled
                      and power electronic assisted systems. The use of batteries
                      is a viable way of smoothing out PV output fluctuations,
                      which is beneficial for EC stability and ultimately
                      lifetime. In our studies of direct coupled PV-EC-battery
                      (PV-EC-B) systems, we have demonstrated self-sustaining
                      operation of the device without control electronics. In
                      addition to the expected storage function, the batteries
                      stabilize the power coupling and improve the
                      solar-to-hydrogen (STH) efficiency of the system despite
                      their own power losses. This synergistic effect originates
                      from the distribution of the daily PV energy over longer
                      periods of EC operation i.e. the reduction of the EC input
                      power and the related kinetic losses. This STH efficiency
                      gain is addressed from two orthogonal viewpoints. First, we
                      investigate how high the synergistic STH gain can be in the
                      optimized system composed of high-efficiency PV and EC
                      components operating close to the system efficiency limit.
                      We show that in a basic day-night operating cycle, an
                      optimally coupled PV-EC system with STH efficiency of 23.0
                      $\%$ can reach STH efficiency of 25.4 $\%$ once battery is
                      included. The STH efficiency increase achieved in the
                      PV-EC-B system is 2.4 $\%$ abs. higher than the STH
                      efficiency in the reference PV-EC system and 1.9 $\%$ abs.
                      higher than the theoretical STH limit of the reference
                      system determined by the EC polarization curve. The second
                      aspect is related to the downscaling of an electrolyzer
                      facilitated by the reduced EC power in the system with
                      battery. We show that the battery allows a reduction of the
                      electrolyzer capacity in the PV-EC-B system by about a
                      factor of two, while operating at the same efficiency as the
                      reference PV-EC system. These results are crucial for the
                      future design, techno-economic and life cycle analysis of
                      advanced PV-powered water splitting.},
      cin          = {IMD-3},
      ddc          = {620},
      cid          = {I:(DE-Juel1)IMD-3-20101013},
      pnm          = {1213 - Cell Design and Development (POF4-121) / DECADE -
                      DistributEd Chemicals And fuels production from CO2 in
                      photoelectrocatalytic DEvices (862030)},
      pid          = {G:(DE-HGF)POF4-1213 / G:(EU-Grant)862030},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:001470368000001},
      doi          = {10.1016/j.ijhydene.2025.04.166},
      url          = {https://juser.fz-juelich.de/record/1041457},
}