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Efficient Power Converters for PV Arrays

SolarBridge Technologies

Scalable Submodule Power Conversion for Utility-Scale Photovoltaics

Graphic of SolarBridge's technology
Program: 
ARPA-E Award: 
$1,099,848
Location: 
Austin, TX
Project Term: 
02/23/2012 to 06/22/2015
Project Status: 
ALUMNI
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 inefficient and failure-prone electrical components used in most PV systems today. Improving the performance of these components 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: 

SolarBridge Technologies is developing a new power conversion technique to improve the energy output of PV power plants. This new technique is specifically aimed at large plants where many solar panels are connected together. SolarBridge is correcting for the inefficiencies that occur when two solar panels that encounter different amounts of sun are connected together. In most conventional PV system, the weakest panel limits the energy production of the entire system. That's because all of the energy collected by the PV system feeds into a single collection point where a central inverter then converts it into useable energy for the grid. SolarBridge has found a more efficient and cost-effective way to convert solar energy, correcting these power differences before they reach the grid.

Potential Impact: 

If successful, SolarBridge would create a power conversion system for solar power plants that is more efficient than conventional methods.

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.

Innovation Update: 
(As of May 2016) 
The team led by SolarBridge has developed a power converter for large scale photovoltaics (PV) to increase the efficiency of converting the low voltage, direct current power from the sun into a higher voltage with an alternating current needed for electricity that is transmitted to customers. Since its ARPA-E award concluded in 2015, SolarBridge has been acquired by SunPower who indicated that the company will conduct economic analyses to determine whether its micro-inverter power converter will provide a net positive impact on their highest-performance PV module products. Initial assessments indicate that a slightly higher up-front premium would provide net benefits from improved yield over the lifetime of the system, but that customer acceptance still needs to be determined. 
 
The more versatile, but more expensive standalone device has demonstrated significant potential performance benefits when combined with new maximum power point tracking (MPPT) algorithms. Using the MPPT algorithms to detect hot spots within PV systems has the potential to increase the lifetime of PV systems from 22 years to 25 years, and the ability to adapt to space-limited sites, in which shading is a serious problem, may enable wider applications.
 
SolarBridge addressed the inefficiencies of converters used in PV technologies by applying the concept of differential power processing (DPP). A key aspect of DPP is that it uses smart signal processing and computational circuits to sense and process only the mismatched power, which is typically a small percentage of the total power produced by the PV panel array. The key challenge the SolarBridge team had to overcome was integrating DPP technology that would successfully increase harvesting efficiency while contributing to a total power inverter cost of less than $0.05/W. With this goal in mind, SolarBridge developed two DPP architectures, one as a standalone unit and one as a micro-inverter-integrated unit. The standalone unit utilized a novel circuit miniaturization and low-power integrated circuit design techniques. The other DPP unit was developed to be directly integrated within SolarBridge’s off-the-shelf-micro-inverter platform. Both units demonstrated greater than 95% converter efficiency and greater than 99.4% power point tracking effectiveness.
 
For a detailed assessment of the SolarBridge team's project and impact, please click here.
 
 
Contacts
ARPA-E Program Director: 
Dr. Michael Haney
Project Contact: 
Dr. Patrick Chapman
Partners
University of Illinois, Urbana Champaign
Release Date: 
9/29/2011