Electrical properties of photogalvanic element with built-in posistor layer based on polymer nanocomposite with carbon filler

Abstract

The study considers the problem of preventing overheat and thermal breakdown of a photovoltaic cell when a high reverse voltage is applied to its p—n junction. The overvoltage protection ability of a structure made up of a photovoltaic cell in direct thermal contact with a built-in posistor layer has been experimentally studied. Fragments of solar cells based on single-crystal silicon were used as a photovoltaic cells. The posistor layer was a polymer nanocomposite with carbon filler used in the resettable fuses of the “PolySwitch” technology. The authors study kinetics of changes in the electrical characteristics of such a structure under constant electric overvoltage on a shaded photovoltaic cell, when its p—n junction is turned on in the reverse direction. It is shown that the current and reverse voltage on the shaded photovoltaic cell are limited and reduced from the moment when the temperature of this structure reaches the values close to the temperature of the phase transition of the posistor nanocomposite to the low-conductive state, which is ≈ 125°С. With an increase in the overvoltage value, a decrease in the response time of the considered protection and an increase in the maximum current value through the structure under study are observed. A decrease in the current value required to reach the tripping temperature by the posistor layer can be achieved by reducing the thermal resistance of the contact between the photovoltaic and posistor elements of the structure. The results obtained indicate the possibility of implementing protection against reverse electrical overvoltage and thermal breakdown of photovoltaic systems based on photovoltaic cells with built-in fuse layers of a specified type.

Modeling of temperature stabilization kinetics of solar cell with posistor layer at local overheating

“…Thus, the solution of the second subproblem (in the time range t > t*) can be realized on the basis of the indicated representations for an elementary section with Tmax within the framework of the model developed in [12,16]. This model is based on the use of heat balance equations considering the thermal contact between the layers of the structure.…”

“…As a first step in this direction, namely, to clarify the effectiveness and features of the overvoltage protection method considered here, experimental and theoretical studies of accompanying electrical effects were fulfilled with using small areas SC, for which the inhomogeneity of prebreakdown heating can be neglected [11,12,16,17]. At the same time, the possibility of implementing protection against reverse electrical overvoltages and thermal breakdown of photovoltaic systems based on such SC with built-in layers based on posistor polymer nanocomposites with carbon fillers was established.…”

Application of a polymer nanocomposite with carbon filler to limit overvoltages in a photovoltaic element

“…The methods and the measurement technique are described in detail in Ref. 36. Figure 6 illustrates the protective effect of the built-in PPTC layer on the kinetics of the effect of electrical overload on the reverse-biased p-n junction of shaded photovoltaic cell.…”

Application of Polymer Posistor Nanocomposites in Systems for Protecting Photovoltaic Components of Solar Arrays From Electrical Overloads

“…photovoltaic cell samples with overvoltage protection based on two-layer structures of monocrystalline silicon PV-cell and polymer posistor nanocomposite with carbon filler (PPTC fuse) are presented in Fig.5.11[119].…”