PV CONNECTION
AC GRID
CONNECTION
Princeton Power systems
MOTOR/
GENERATOR
DC ENERGy
S TORAGE
According to Princeton Power Systems’ Darren Hammell, “What we tried to do
with the DRI is make it a real turnkey, one-box solution that arrives on site and is
flexible enough to allow multiple different kinds of systems and configurations,
but it only requires you to change a couple of software parameters.”
In the mid-’90s, years before the Princeton Power founders began focusing on the DRI,
Distinguished Member of the Technical Staff Bower was pitching the U.S. Department of
Energy (DOE) a program aimed at making PV more useful on the grid. Bower designed Sandia’s original PV inverter test facility back in the 1970s and later patented an AC PV building
block concept that integrates with microinverters to deliver a complete PV system. He had
long believed the industry needed to deliver communications-integrated systems that enable
utilities and their customers to take advantage of power conditioning, load shifting, demand
response, interactive controls and other value-added features. “We weren’t interested in
evolutionary — we wanted revolutionary changes” with the SEGIS program, he said.
Industry technology and the market finally aligned in 2007, when DOE launched the
Solar Energy Grid Integration Systems (SEGIS) program with funds administered through
Sandia. Over the course of the three-year-program, DOE and Princeton Power will have
invested more than $9 million to develop the DRI. In addition, Sandia provided technical
support, reviewing SEGIS participants’ proposals and progress, providing early-stage testing
and then testing prototypes for both legacy and smart-grid applications. All of the SEGIS
participants partnered with electric utilities, communications and other system-related
technology experts during the program.
Copyright © 2011 by the American Solar Energy Society Inc. All rights reserved.
Inside the DRI
rinceton Power System’s demand-
response inverter (DRI) integrates a
photovoltaic array, energy storage bank,
backup generator and electric grid con-
nection into one system — providing
simultaneous control of each of these
components through one programma-
ble interface. A DRI system can provide
sophisticated services, such as peak
power limiting, power factor correction
and demand response, automatically
to the electric grid operator. It can also
operate as a secure “microgrid” with no
grid connection at all. The DRI provides
these functions in a turnkey solution for
various configurations at the commer-
cial scale (100 kilowatts and larger), an
effort that otherwise requires custom
integration of multiple components.
