Technological Innovation #2: Solving DC Arc Faulting
Another significant safety and performance problem solar power industry participants are trying to solve is the potential for DC arc faults to occur in solar PV panels. When they occur, the results can be spectacular, and spectacularly dangerous.
“DC arc faulting is the most dangerous aspect of current solar power architecture,” Kernahan stated. “It’s one advantage micro-inverters have over standard DC solar panels. Because they’re using AC, they don’t have this problem.”
Akin to what occurs in arc welding or lightning, the DC electricity flowing through a solar panel can arc when a gaseous-liquid plasma is formed from the insulating materials inside it. At that point the insulating material “becomes a low impedance conductor,” Kernahan elaborated.
“In a plasma arc, the air is ionized and goes into a plasma state. As DC is continuous, the arc can be quite long – many millimeters, up to centimeters long – and it’ll keep going as long as there’s a power source. As that’s the sun, this can happen all day.
“A plasma arc in air can reach 7000 degrees Kelvin, about 14,000 degrees Fahrenheit. It will evaporate any material on the planet. The solar panel materials become fuel after about two minutes exposure to this. The molten silicon and solar panel parts start falling from the solar panel frames.”
Just such an event took place with a a BP solar PV factory BP solar panel array on a warehouse in Burgstadt, Germany in 2009, an industrial accident that resulted in millions of dollars worth of damage to the facility, as well as neighboring homes and businesses, Kernahan noted.
Solar PV researchers at Australia’s University of South Wales recreated the solar module DC arc fault failure.
The second significant innovation Kernahan’s passing on to Ideal PV and Locally Grown Power is a “fundamental way of putting out arc faults in a few thousandths of a second.”
Kernahan’s method extends across the entire wiring plan, providing “a fundamental advantage for a DC solar PV plant as compared to the use of micro-inverters, which used to be much safer by comparison,” he stated.
Asked if the power output of the array doesn’t have to come down as the result of an arc, Kernahan responded that “it certainly doesn’t have to, though it may have to per code requirements. The arc would be put out and the array could go back into production within fractions of a second.”
Ideal PV & Locally Grown Power: Locally Grown, Locally Consumed Solar Power
Solving the reverse bias-hotspot and DC arc fault problems associated with DC solar panels will yield another significant competitive advantage to Ideal PV-Locally Grown Power and local partners, according to Kernahan.
It will enable the factories Locally Grown Power and local government or non-profit groups establish to make use of crystalline silicon wafers rejected for use by most solar cell and module manufacturers due to impurities. A large, nationwide wholesale market exists for this scrap polysilicon.
“That’s a big deal,” Kernahan told CleanTechnica. “It turns out that two to three percent of the silicon made for silicon solar cells is rejected due to this reverse bias problem. It’s sold for as little as $0.25 a Watt.”
The primary motivation and guiding purpose of forming Ideal PV and Locally Grown Power extend much more broadly, however. They aim to demonstrate a means by which US inventors can directly participate in solving the critical economic problems sluggish good job creation and the loss of manufacturing has had and continues to have on the US economy.
“Locally Grown Power is intended not just as a nice little business for myself and my four partners, but a demonstration of a process that can be used by US inventors to solve a critical problem,” he explained.
Joining with Locally Grown Power to start-up and run a solar PV plant based on Ideal PV’s intellectual property, municipal and/or local non-profit groups would have “a sustainable economic stimulus and development program,” Kernahan said.
He and his partners are working with community organizers and city officials to put the first factory up in 2012. “It’s a franchise model where Ideal PV specifies the equipment and provides the training. The son of a minister, it’s based on the “teach a man to fish concept,” Kernahan relates.
“We basically set up their factory for the people they will hire and provide the intellectual property they’ll need to manufacture, assemble and install the panels. It’s essentially a local product with a local supply chain.”
The locally produced-locally consumed solar PV power business model they’ve come up with certainly faces challenges. For one thing, it’s a business model and public-private venture that isn’t likely to attract investments from venture capital firms or Wall St. investment banks.
“They aren’t likely to go for this one,” Kernahan commented. “You really can’t have VC finance for this because that’s the thing that forces you to go into production in Asia, so we’re asking for all the help we can get regarding creating public-private partnerships.”
At the end of the day, that may prove to be the biggest and best innovation that comes out of Kernahan and partners’ experiment with Ideal PV and Locally Grown Power.