In 1891, Edward Acheson was working at Thomas Edison’s famed Menlo Park laboratory, trying to make artificial diamonds by heating clay and powdered coke in an iron bowl with a carbon arc light. The result wasn’t pretty. Instead of diamonds, he created silicon carbide—a hard and rough compound used for decades mostly as an abrasive in industrial sandpaper, grinding wheels and cutting tools, and later a grip tape for skateboard decks.
But Acheson’s accidental discovery is getting a second life as a miracle material for power management chips that could revolutionize everything from planes and locomotives to medical equipment. One of silicon carbide’s latest applications is inside solar inverters, the devices that switch direct current (DC) from solar panels into alternating current (AC) that flows from the wall outlet. GE, which Edison founded, brought its latest version this month to the Solar Power International trade show in Las Vegas and to the Intersolar trade show in Dubai.
Owen Schelenz, Product Leader of GE Power Conversion, calls the “utility-scale” device “nothing short of a revolution for solar power business.” He says the system, called LV5+ Series Solar Inverter, uses silicon carbide (SiC) power electronics to convert solar power more efficiently, increasing energy production for solar farm operators. “This helps to reduce the “levelized cost of electricity” (LCOE)—a key industry metric measuring the cost of electricity,” Schelenz says.
Schelenz says that GE’s modules with silicon carbide (SiC) MOSFET—metal-oxide field effect transistors—in the LV5+ help produce more energy in a smaller footprint than today’s inverters made with silicon-based IGBT transistors. This improves power-conversion efficiency by approximately 1 percent, Schelenz says.
That’s enough to produce over $2.5 million worth of additional energy generation over the lifetime of a 100 megawatt (MW) plant. In addition, SiC generates less heat loss than silicon and has a simpler design.
GE has been testing the first utility-scale prototype SiC inverter in the GE Power Conversion lab in Berlin for the past two years.
The technology included in the LV5+ Solar eHouse Solution solves another quandary facing solar plants—how to turn power plant transformers on and off safely. Shutting them down at night can cause voltage spikes, and reconnecting them to the grid produces a large inflow of current, putting mechanical stress on equipment and shortening its life.
As a result, many operators leave equipment on overnight, consuming a couple of kilowatts while the inverter is not producing power during the nighttime hours—a cost of $800,000 over a 100MW plant’s life. Using intelligent controls, the LV5+ equalizes the voltage at the transformer and at the grid, allowing transformers to be connected or disconnected smoothly and cleanly.
The end result is more cost savings for customers, Schelenz says.