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The manifestation and formation of various defects in the process of exploitation in real photovoltaic cells and their compounds as well as their work in the regime of changing non-uniform illumination lead to the so-called series and parallel inconsistencies (differences of electrical characteristics) between separate cells and their groups. This results in local overheating and intensifying of degradation processes. In some cases temporary disconnection (isolation) of the corresponding elements of the solar batteries is more appropriate in order to increase their service life. In this work additional devices for insulation of overheating cells (and/or components) of solar batteries such as “PolySwith” resettable fuses are proposed to be used as a perspective solution of such problems. These structures are polymer composites with nanosized carbon fillers. Electrical resistance of such a fuse increases abruptly by several orders of magnitude when certain threshold temperature is reached, and when the temperature decreases the fuse returns to its initial high-conductivity state. This study investigates the possibilities of using the specified type of fuses for electrical insulation of «overheated» photovoltaic cells. Particular attention is paid to the research of the effect of fuses on the working of the solar batteries in the operating temperature range and their functional applicability in emergency situations associated with overheating. The studies were carried out using a model structure of several series of parallel connected photovoltaic cells and specified fuses. Attention is paid to the influence of such factors as the ambient temperature and the drift of the fuses resistance in the conducting state in the process their multiple switching. It has been established that such protection elements do not influence the work of solar batteries in operating temperature range and are functionally applicable for the electrical isolation of local regions and components of solar batteries with increased temperature.

The results of experimental study of the transformation of the light current-voltage and volt-watt characteristics for the parallel connections of photovoltaic modules when using “PolySwitch” polymer resettable fuses are given. The conditions for selecting such fuses which allow their correctly triggering and minimize the current overload are formulated and experimentally verified. It is established that if resettable fuses are connected in series to the circuits of all photovoltaic modules, which are connected in parallel thus forming a unit, this prevents such a situation as the complete loss of electrical energy generated by this unit due to the short circuit of one of its modules. At the fuse triggering the total power loss of the unit of  parallelly connected photovoltaic modules is mainly determined by the decrease of its current by the amount that is equal to the current of the disconnected photovoltaic module.

The problems of reducing the cost of ensuring the safe operation of solar cells by using low-cost elements of solid-state electronics to protect against overvoltage photovoltaic cells of solar arrays are considered. The results of experimental studies of the use of a varistor-posistor structure based on a metal oxide varistor and PPTC fuses of the PolySwitch type being in thermal contact to prevent overvoltages in series connections of photovoltaic cells are presented. General schemes for using the considered solid-state structure to limit the indicated constant overvoltages are given and justified. The requirements to the parameters of this structure are determined and experimentally verified. It is shown that such a device makes it possible to limit the long-term constant overvoltages that occur in photovoltaic arrays at the level of photovoltaic cells in the case of their malfunction or shadowing, which can lead to fire hazard and other “abnormal” situations during the operation of solar electric energy sources.

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