Project Name: Modular HF Isolated Medium-Voltage String Inverters Enable a New Paradigm for Large PV Farms
Funding Opportunity: Advanced Power Electronics Designs for Solar Applications
SETO Subprogram: Systems Integration
Location: Atlanta, GA
SETO Award Amount: $1.9 million
Awardee Cost Share: $500,000

This project team will develop an autonomous medium-voltage string inverter for commercial- and utility-scale photovoltaic (PV) farms, or systems, that can connect direct current from solar systems to standard utility distribution voltage. This ability will eliminate the need for a transformer, which converts current from one voltage to another, increasing efficiency and reducing both balance of systems cost and the levelized cost of energy (LCOE).


The team will design the inverter with an integrated high-frequency transformer that uses a process called soft switching, which filters out high-frequency current oscillations to reduce stress on the device. With input from the solar industry and the utility sector, the team will define the architecture and specifications of large-scale PV farms with direct medium voltage connections enabled by the integrated high-frequency transformer. Using a laboratory grid simulator, they will demonstrate how the new inverter works with integrated energy storage to provide ancillary grid services. The team will perform regulatory and commercial impact analysis to identify market opportunities, distribution channels, and any potential barriers to commercialization. 


The new inverter will lower capital and operating costs, reduce energy losses achieving greater than 97% efficiency for direct medium voltage connections, optimize the performance of the PV array, and reduce fault modes on account of its small size. Additionally, the system will be able to easily integrate energy storage without having to add one more conversion circuit, resulting in a lower LCOE.