Efficient Switches for Solar Power Conversion

Transphorm, Inc.
Four-Quadrant GaN Switch Enabled Three-Phase Grid-Tied Microinverters
Graphic of Transphorm's technology
Program: 
ARPA-E Award: 
$2,446,247
Location: 
Goleta, CA
Project Term: 
03/19/2012 to 03/31/2015
Project Status: 
ACTIVE
Technical Categories: 
Critical Need: 
Photovoltaic (PV) solar systems convert the sun's energy into electricity, but only a small percentage of the sunlight that reaches a PV system is converted into useful electricity. This is due in part to the inefficiency of inverters for converting direct current (DC) output of solar cells to alternating current (AC) power needed for the grid when the intensity of the sunlight is low. Failure-prone electrical components used in most PV systems today also reduce system reliability. Improving the performance of switches and components used in inverters would lower the overall cost of PV systems--helping to make renewable solar energy cost-competitive with conventional, nonrenewable forms of electricity generation.
Project Innovation + Advantages: 
Transphorm is developing power switches for new types of inverters that improve the efficiency and reliability of converting energy from solar panels into useable electricity for the grid. Transistors act as fast switches and control the electrical energy that flows in an electrical circuit. Turning a transistor off opens the circuit and stops the flow of electrical current; turning it on closes the circuit and allows electrical current to flow. In this way a transistor can be used to convert DC from a solar panel into AC for use in a home. Transphorm's transistors will enable a single semiconductor device to switch electrical currents at high-voltage in both directions--making the inverter more compact and reliable. Transphorm is using Gallium Nitride (GaN) as a semiconductor material in its transistors instead of silicon, which is used in most conventional transistors, because GaN transistors have lower losses at higher voltages and switching frequencies.
Impact Summary: 
If successful, Transphorm would develop solar inverters that would be over 98% efficient at converting solar energy into useable electricity, thereby improving performance and reducing the operating cost of the entire PV system.
Security: 
Lowering the cost of PV systems would help increase the use of solar energy, which in turn would decrease our dependence on fossil fuels and improve U.S. energy security.
Environment: 
Solar energy systems create zero harmful emissions while providing energy to homes and businesses, so their widespread use would significantly improve air quality.
Economy: 
This project could help position the U.S. as a leader in the power electronics industry.
Contacts
ARPA-E Program Director: 
Dr. Timothy Heidel
Project Contact: 
Dr. Rakesh Lal