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When a solar cell in a panel is shaded, the illuminated cells can place a large reverse bias on the shaded cell to attempt to force current through it. Although the panel can continue to produce power, the reverse bias can cause significant problems for the shaded cell. In the case of perovskite solar modules, Joule heating and irreversible electrochemical reactions will degrade the cell. Some photovoltaic technologies use bypass diodes to solve this problem. To prevent both a perovskite cell and an all‐perovskite tandem cell from falling into reverse bias breakdown while shaded, no more than two cells per bypass diode are allowed, which is likely to be prohibitively expensive for many applications. Herein, how many solar cells can be protected by one bypass diode in single‐junction and multijunction perovskite modules is explored. It is easier to incorporate bypass diodes into modules with singulated cells than with monolithic panels. It is shown that perovskite–silicon tandems can be protected with fewer bypass diodes than with single‐junction perovskite modules. It is suggested that if bypass diodes cannot be feasibly incorporated, then the panels should be deployed in utility‐scale power plants. [ABSTRACT FROM AUTHOR]

One of the key challenges of perovskite photovoltaics (PV) is the long‐term stability. Although efforts are made to improve the lifetime of perovskite PV devices, their degradation under reverse‐bias conditions is barely addressed. Herein, perovskite solar cells with carbon‐based electrodes are presented which demonstrate superior resilience against reverse‐bias‐induced degradation. Although their breakdown voltage is identified to be at approximately −3.6 V, cells do not degrade until the applied reverse‐bias exceeds −9 V. Two main degradation mechanisms are identified: 1) iodine loss due to hole tunneling into perovskite, which takes place even at low reverse‐bias but decomposes the perovskite only after long time durations; and 2) rapid heating at large reverse‐bias leading to formation of PbI2, which starts at shunts and then follows the path of the least resistance for the cell current, which is primarily influenced by the electrode sheet resistances. Finally, perovskite solar modules with carbon‐based electrodes are demonstrated, which are subjected to a "hotspot" test described in the IEC 61215:2016 international standard at an accredited module testing laboratory. Passing this accelerated test for the first time confirms the superior stability of perovskite PV devices with carbon‐based electrodes and highlights their large industrialization potential. [ABSTRACT FROM AUTHOR]