Material helps extinguish solar panel fires before they ignite

By Manette Newbold Fisher

Thursday, November 19, 2020

Albuquerque company works with Sandia to develop special polymer for flame prevention device

Close-up of researcher working on arc-fault generator
ARC FAULT PREVENTION — Sandia researcher Kenny Armijo uses an arc-fault generator developed by researchers to determine how dangerous arc faults are. (Photo by Bret Latter)

As solar panels become popular and their voltages increase, there is a need to have built-in capabilities that can extinguish fires caused by arc faults, which are high-power discharges of electricity that can create explosions or flash events due to damaged wires.

Sandia researcher Kenny Armijo has spent 10 years working alongside other researchers at the Labs and Albuquerque company Guardian Sensors Inc. to understand and characterize these hazardous arc faults. Their work led to the devel­opment of electrical in-line connectors that auto­matically predict and prevent photovoltaic arc faults before they can ignite electrical fires.

“As solar panels become more efficient, they’re able to produce more power,” Kenny said. “More power means that they’re going to have higher cur­rent and higher voltage levels. As you increase the current and voltage levels in next-generation solar panels, it becomes a bit more dangerous because as you increase the voltage, you get a higher propensity for arc faults. This new self-extinguishing mecha­nism could solve that problem.”

in-line connector
IN-LINE CONNECTORS — This image shows the inside of a self-extinguishing in-line connector developed by New Mexico company Guardian Sensors. The device is about the diameter of a dime and contains a metal spring covered in a special type of self-extinguishing polymer material developed and tested at Sandia over the past five years. (Photo courtesy of Kenny Armijo)

The in-line connector developed by Guardian Sensors — about an inch long and the diameter of a dime — contains a metal spring covered in a special type of self-extinguishing polymer material developed and tested at Sandia over the past five years. Like current connectors, the self-extinguishing mechanisms would link a series of solar panels like a string of Christmas lights that could operate together in a field or on a roof.

All connectors are susceptible to corrosion, damage or improper installation, which can lead to reliability issues, especially if there are tiny crevasses or breaks in the wires. Currently, when this happens, sparks and devastating fires can occur when high current and voltage run through damaged connectors, and unfortunately, there isn’t a completely reliable way for the connectors themselves to prevent the danger. That’s where the new device would fill that gap, Kenny said.

Increasing the spark gap

The new in-line connectors have been built to activate at temperatures above 185 degrees Fahrenheit. When that happens, the special self-extinguishing material melts, fills in the crevasses or breaks in the wires and extends the spring, which increases the spark gap between wire con­ductors so they can no longer produce energy that leads to heat and fires. A combination of the speed of the reaction and the material’s fire-resistant prop­erties will stop a fire before it starts — in less than two seconds, Kenny said.

researcher testing high-voltage connector
HIGH-VOLTAGE TESTING — An arc-fault generator at Sandia can test different materials for reliability in high-voltage connectors and electrical wiring. (Photo by Bret Latter)

The self-extinguishing materials used in the con­nectors were developed from Sandia-based research originating out of the Laboratory Directed Research and Development program. Current work with Guardian Sensors is funded through the New Mexico Small Business Assistance Program that provides technical assistance from Sandia and Los Alamos national laboratories to companies seeking to solve scientific problems.

Through the NMSBA program, Sandia provided Guardian Sensors access to a patented, special arc-fault generator at the Labs. It was developed by researchers working to determine how dangerous arc faults are, and it can test different materials for reli­ability in high-voltage connectors and electrical wir­ing. For this project, Kenny tested a prototype of the connector for Guardian Sensors using the arc-fault generator, and results were successful.

Kenny has several photos, videos and data from multiple tests. One significant example shows a graph of lines that increase as voltage spikes, “then bam — the self-extinguishing mechanism works,” he said, pointing to where all lines on the graph make a sudden vertical decline to zero.

arc fault connector test and chart of voltage measurements
STOPPING FIRES — These images show an example of a connector test, conducted at Sandia, at the moment of an arc fault and sudden self-extinguishment. The photo shows a fire from an arc fault while a self-extinguishing material melts and a spring extends inside the connector to facilitate a larger spark gap and stop the flames. The graph depicts self-extinguishment with a sudden voltage drop that occurred in less than a second. (Images courtesy of Kenny Armijo)

“You see this rapid shutdown, and it does it on its own,” he said. “To me, that is telling because it’s effectively a set-it-and-forget-it kind of system. I think that’s truly what makes this whole system really useful and impactful.”

Company earns prestigious awards

As a result of the technical assistance and suc­cess, Guardian Sensors received $225,000 in cash and vouchers from the DOE American-Made Solar Prize and provided research opportunities to three New Mexico universities. The company also was able to hire a new engineer and expand.

In addition, the company was awarded the Honorable Speaker Ben Lujan Award for Small Business Excellence, presented to an NMSBA participant that demonstrates the most signifi­cant business growth for the betterment of the New Mexico economy through sustainability and workforce development.

“I highly recommend the NMSBA program because with technical assistance, we were able to test and validate the circuit interrupters,” said Guardian Sensors program manager Kenny Blemel. “We could not have accomplished this without the help of Sandia researchers and special equipment. We look forward to taking this to market for the benefit of companies providing alternative energy sources and for the public’s safety.”

In the future, Kenny said he hopes research can expand to other types of power sources and storage devices, like batteries.

“We’re looking at expanding this research to more than just connectors,” Kenny said. “I think the next step is seeing if we can extend something like this into energy storage, like batteries or any­thing that holds charge. At the end of the day, the way to make renewable energy work and be more adopted is to have storage, and Guardian Sensors and I are developing ideas and research around advanced energy storage technologies that will mit­igate arc faults.”