A new world record of 99.03 % for the efficiency of inverters used in photovoltaic systems has been set by the Fraunhofer Institute for Solar Energy Systems ISE. Key to the new record was using junction field-effect transistors (JFETs) made of silicon carbide (SiC) manufactured by SemiSouth Laboratories as well as improving the circuit technology used in the device.
The world record was measured for a complete PV inverter, according to Fraunhofer, including its internal power supply, a digital signal processor (DSP) for controls, an LCL grid filter and a relay for grid connection.
Fraunhofer ISE expects the components to be transferred to production inverters in the future as other benefits were seen with lower thermal losses, smaller cooling devices being used, and a more compact construction. Field tests are planned to demonstrate viability in practice. SiC transistors perform better than conventional IGBTs of silicon as well as offer significant performance advantage in higher reverse voltage applications.
“I see enormous potential for the new silicon carbide transistors,” noted Prof. Bruno Burger, leader of the Power Electronics Group at Fraunhofer ISE. “They are constantly becoming better and less expensive, whereas the costs for passive components, which contain significant amounts of copper and other metals, are rising continuously.”
According Fraunhofer, a 30kW inverter system, with an efficiency value of 1% higher than normal systems, results in an additional yield over 10 years of 3000kWh or €1300.