Detecting a physical damage or an internal malfunction in a solar panel
Updated: Dec 15, 2021
A physical damage or an internal malfunction in one of the panels in a solar photovoltaic system causes an output reduction, which can range from a loss of a single panel output in the case of string inverters with optimizers or micro-inverters to a loss equivalent of two to five panels in a mini central inverter connected to several strings. Sometimes this can even lead to the disconnection of an entire string (in the worst case - a panel fault ana a bypass diode fault altogether).
The solar panel is a very important part of a solar photovoltaic system, because without the panels there would be no power output. The panels are arranged in special and predetermined configurations - chained into strings (arrays), with each string or number of strings connected to an inverter input. Damage to the integrity of a single panel usually harms not only the panel itself, but also the string in which it is located and even affects neighboring strings connected to the same mini-central innverter input channel due to the electronic link between them. Remote detection of physical damage to a solar panel within strings of a mini-central inverter is almost impossible via existing manual monitoring software.
However, for the most part is in fact possible by onsite visual inspection, although every few years it is worthwhile to also perform an electronic measurement test of string voltages or a thermal imaging (infrared) for higher resolution detection. The problem with these onsite methods is however the delayed detection of panel failures and high costs, depending on the frequency of such panel inspections. Thus, more advanced methods have been developed that allow remote detection of panel failures in real time with the help of hardware sensors or via software performance analysis.
The first solution developed in the global solar market for the problem of remote detection of individual panel failures was to connect each panel to a separate micro-inverter such as Enphase, which also allows panel-level power optimization and measurement of performance. The micro-inverter solution proved to highly successful for the residential scale, but has encountered difficulties in the US commercial market due to relatively high cost of components. Another common solution in the residential market came via another technique - connecting all the panels in the PV system to electronic control boxes with separate voltage maximizers, such as the Tigo maximizer or the SolarEdge optimizer, while keeping the string inverter. This type of solution of course also requires an additional cost per panel, but without a doubt it has had some success in penetrating also into the small commercial market in the US and Europe.
An innovative and cheaper solution for real-time detection of panel faults in mini-central inverter PV systems (mainly commercial and industrial scale) is a cloud-based tool for inverter performance analysis of IV curves, such as the one implemented by Soltell Systems. The Smart Solar & Storage Management Platform (SysMap) algorithm can be retrofitted to mini-central inverter PV systems, without the need to install voltage maximizers or mico-inverters, while providing a warning panel failures according to output data received via innverter's MPPT sensors.
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