As the PV market continues to mature and solar energy becomes a growing source of energy, there are efforts to make PV systems even safer than they currently are. To date, the industry has developed increasingly stricter safety standards, such as Rapid Shutdown and arc detection. SolarEdge recently announced a safety innovation that is designed to detect heat abnormalities and initiate shutdown before an arc occurs and extends safety to the connector level.
Fires in PV systems are fairly uncommon due to both quality manufacturing and regulatory standards. One of the strictest safety standards is the Arc Detection UL 1699B standard. This calls for detection of arcs as they occur, which is a limited approach because mechanical damage might have already been caused and an arc may have already occurred which can ignite a fire.
SolarEdge began by focusing on heat, which is always a precursor to fire – no matter what the root cause of a fire may be. Then they identified the amount of heat that connectors can withstand before becoming flammable. This meant that if implemented correctly, they could develop a technology that would be designed to detect and react to heat abnormalities before an arc occurred in order to prevent potential fires. However, this was only the first step, the next challenge was to leverage this knowledge and develop it into a technological innovation.
There were two developmental hurdles to overcome. The first, was detecting heat abnormalities, which presented a challenge because electronics are already hot due to environmental conditions and natural thermal dissipation. This meant that there was a very small margin of error for detection. To overcome this, both a physical and a computational solution was needed. By including multiple temperature sensors into the module-level electronics, it is possible to gather multiple temperature readings to analyze heat dissipation patterns. This needed to be combined with the development of a complex algorithm with adaptive learning that could filter out thermal background noise in order to detect real increases to absolute and relative temperatures. The second challenge was that connectors tend to be located at a distance from electronics, which in turn makes detection even more complicated due to increased heat dissipation. In order to address this, the power optimizer cable architecture was altered, which enabled repositioning the connectors closer to the sensors embedded in the module-level electronics. In addition, the natural thermal conductivity of copper wire was leveraged in order to increase the precision of the thermal readings.
Solution monitors heat, shuts down system
This solution offers a completely new approach in PV system safety. Unlike typical safety solutions that are developed in reaction to new standards, this innovation is a proactive approach that aims at preventing fires before they start. Currently, even the most advanced safety solutions only protect against fires from certain type of arcs, but do not have a solution for detecting resistive heat sources. This new innovative technology is designed to monitor heat, shut down the system if necessary, and send an alert to the monitoring platform about potential issues that require inspection. This new technology not only is designed to mitigate the risk of fires, but also extends shutdown from the current module level to the connector level.
While regulatory safety standards will always be crucial in setting industry-wide guidelines, the process of developing them can be both complex and timely. On the other hand, technological innovation can help improve safety at a faster pace, which can lead to an increased rate of PV proliferation as safety concerns are addressed and perception of PV safety is improved.
Written by Mr. Lior Handelsman, VP Marketing and Product Strategy and Founder of SolarEdge