In a test using prototype silicon carbide-based MOSFETs (Metal Oxide
Semiconductor Field Effect Transistors) manufactured by CREE, the
Fraunhofer Institute for Solar Energy Systems ISE has said it has
achieved a maximum efficiency rating of 98.5 percent for photovoltaic
inverters, the highest such rating to date, according to the institute.
The higher the efficiency rating of the inverter, the
greater the energy yield of the entire photovoltaic system. The silicon
carbide MOSFETs have not been made available before for PV applications.
“Silicon
carbide components switch faster and have a smaller forward bias power
loss than traditional silicon-based transistors,” says Dr. Bruno
Burger, head of the Power Electronics Group at Fraunhofer ISE.
Fraunhofer ISE is the first organization known to test silicon carbide
MOSFETs in this application. “Our work involved characterizing the
components and integrating them into existing inverters. If, in a
further step, the inverter circuitry is optimized specifically for
silicon carbide, then even greater efficiencies could certainly be
achieved.”
The Fraunhofer team achieved the
efficiency rating record with a single-phase inverter with their
patent-pending ‘HERIC’ topology and a nominal power rating of 5
kilowatts. They also increased the efficiency rating of a three-phase
inverter with a nominal power rating of 7 kilowatts from 95.1 to 97.5
percent.
Fraunhofer researchers succeeded in reducing the power
dissipation of conventional inverters by 30 to 50 percent when compared
with results obtained using traditional silicon-based transistors.
