New High-Rate and Long-Duration Capabilities and Customizable---- System Configuration Options Deliver Increased Flexibility and Optimized Performance for Broad Range of Grid Applications

WALTHAM, Mass., May 1, 2012 -- A123 Systems (Nasdaq:AONE),

a developer and manufacturer of advanced
Nanophosphate(R) lithium iron phosphate batteries and systems, today
announced the expansion of its portfolio of Grid Storage Solutions (GSS).
A123's GSS product line now includes high-rate and long-duration systems
ranging from kilowatt-scale to hundreds of megawatts, enabling customers to
deploy a complete, turnkey storage solution that meets their specific power
and energy requirements. A123 will showcase its industry-leading grid energy
storage solutions at the ESA Annual Meeting, May 2-4, 2012, Washington, DC
(booth #210).

"A123 Systems is the world's leading provider of lithium ion battery
solutions for grid-scale energy storage, and our experience in deploying
systems for customers worldwide has given us great insight into how
utilities expect storage solutions to integrate with their existing
systems," said Robert Johnson, vice president of the Energy Solutions Group
at A123. "We have applied the knowledge we have gained through this
experience to expand our product offerings, which we believe will enable us
to capitalize on the growing global grid energy storage market and augment
our leadership position in this segment."

The modular architecture and flexible design of A123's GSS optimize
performance and increases system efficiency to increase the stability and
reliability of the grid while enabling the seamless integration of renewable
power sources. A123's fully integrated, grid-ready GSS are designed as
complete solutions capable of achieving greater than 90 percent AC to DC to
AC roundtrip efficiency. Each GSS consists of a Grid Battery System (GBS),
AEROS(TM) software and a Power Conversion System.

The GBS is based on modular, rack-integrated energy storage units which
serve as the building blocks for easily configurable high-rage and
long-duration systems designed to meet application-specific requirements.
A123's GBSs are available with onboard touch screen control panels, heat and
smoke detection, and fire suppression to provide customers with the
necessary infrastructure to integrate the GSS with their existing systems.
In addition to A123's standard containerized GBS units available in 20-foot,
40-foot and 53-foot lengths, A123's rack-integrated battery systems can be
deployed in buildings or other custom enclosures.

In addition to the Grid Battery System, the GSS feature A123's Energy
Response Operating System (AEROS), the company's proprietary software
designed to deliver full command and control functionality for seamless
integration with existing utility systems. AEROS is designed to increase the
efficiency and optimize the performance of the energy storage system by
enabling automated command and control with built-in secure protocols, real
time reporting of systems capabilities and performance, millisecond response
times and multiple operating modes to optimize customers' application
requirements. A123's GSS are also equipped with high-efficiency power
inverters that convert DC to AC and AC to DC to provide real and reactive
power as well as bidirectional energy flow to the grid.

About A123 Systems

A123 Systems, Inc. (Nasdaq:AONE) is a leading developer and manufacturer of
advanced lithium-ion batteries and energy storage systems for
transportation, electric grid and commercial applications.
The company's proprietary Nanophosphate(R) lithium iron phosphate technology
is built on novel nanoscale materials initially developed at the
Massachusetts Institute of Technology and is designed to deliver high power
and energy density, increased safety and extended life. A123 leverages
breakthrough technology, high-quality manufacturing and expert systems
integration capabilities to deliver innovative solutions that enable
customers to bring next-generation products to market. For additional
information please visit www.a123systems.com.