Beacon Power to Highlight Smart Power M5 Inverter at UPEx 2003 Solar Conference in Scottsdale, AZ.

Business Editors/High-Tech Writers

WILMINGTON, Mass.--(BUSINESS WIRE)--Sept. 17, 2003

Will Also Demonstrate New Software for Photovoltaic System

Performance Tracking

Beacon Power Corporation (NASDAQ: BCON), a leader in sustainable energy storage and power conversion systems, will present the newly engineered Smart Power M5 power conversion system at the 8th annual UPEx Solar Electric Power Conference and Technology Exhibition. This national event, organized by the Solar Electric Power Association in conjunction with the Solar Energy Industries Association, will be held in Scottsdale, Arizona, from October 7-10.

In addition to displaying the M5 and highlighting its features and enhancements, Beacon will also demonstrate its new Smart Power Monitor software. Smart Power Monitor is a PC-based software solution that monitors, analyzes and reports the performance of an M5-based solar power system. Users can observe and record key system performance parameters, including solar power output (real-time and accumulated), power exported to the grid (for net metering applications), and battery charging and discharging functions.

Bill Capp, Beacon Power president and CEO, said development and testing on the Smart Power M5 are nearly complete. "We've made several important changes in the product to improve reliability and performance. We look forward to delivering evaluation units to a number of distributors early in the fourth quarter."

The Smart Power M5 is a high performance 5-kilowatt inverter for grid-connected solar power applications. It incorporates a range of components in one compact, integrated system, including inverter, charge controller with maximum power point tracking, switchgear, and battery back-up capability. Even in the event of a grid outage, the M5 will continue to operate as uninterruptible power system (UPS), providing photovoltaic (or battery) power to critical loads. Traditional grid-tied inverters do not function when primary power fails.

About Beacon Power Corporation

Beacon Power Corporation (NASDAQ: BCON) designs and develops sustainable energy storage and power conversion solutions that provide reliable electric power for the renewable energy, telecommunications, distributed generation and UPS markets. Beacon's latest product is the Smart Power M5, a 5-kilowatt inverter for grid-connect solar power applications. The Smart Power M5 is an "all-in-one" power conversion system incorporating multiple high-performance components in one unit that delivers uninterruptible power in the event of a grid outage. Beacon Power is also known for its advanced flywheel-based Smart Energy systems, designed to provide highly reliable, environmentally friendly power quality solutions for electric utility transmission and distribution and other applications.

For more information call 888-938-9112, or visit www.beaconpower.com.

Safe Harbor Statements under the Private Securities Litigation Reform Act of 1995:

Material contained in this press release may include statements, which are not historical facts and are considered "forward-looking" within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements reflect Beacon Power Corporation's current views about future events and financial performance. These forward-looking statements are identified by the use of terms and phrases such as "believe," "expect," "plan," "anticipate," and similar expressions identifying forward-looking statements. Investors should not rely on forward-looking statements because they are subject to a variety of risks, uncertainties, and other factors that could cause actual results to differ materially from Beacon Power Corporation's expectation, and Beacon Power Corporation expressly does not undertake any duty to update forward-looking statements. These factors include Beacon Power Corporation's short operating history, its history of losses and anticipated continued losses from operations, its need to raise additional capital, the fact that its stock has moved from the National Market System to the SmallCap Market, its limited experience manufacturing flywheel energy storage systems on a commercial basis including the fact that no commercial contracts have been executed to date, the dependence of Beacon Power Corporation's sales on the achievement of product development and commercialization milestones, the adverse effect of the uncertainty of the political and economic climate of any foreign countries into which we sell, including the uncertainty of enforcing contracts in those countries and the potential substantial fluctuation in currency exchange rates, significant technological challenges including the risk of successfully developing its flywheel products as well as the commercial viability of these flywheel products, Beacon Power Corporation's dependence on third-party suppliers, intense competition from companies with greater financial resources than Beacon Power Corporation, the risk that government regulation may impede Beacon Power Corporation's ability to market its products, possible product liability claims that may or may not result from safety failures of Beacon Power Corporation's flywheels and the negative publicity which could result, any failure to protect Beacon Power Corporation's intellectual property, any failure to hire and retain key executives and the fact that Beacon has reduced its workforce substantially during 2002, the lack of availability of additional financing, the recent volatility in the stock price of companies operating in the same sector as Beacon Power Corporation, control by Beacon Power Corporation's controlling shareholders and the limited ability of other investors to influence the outcome of matters requiring shareholder approval, conditions in Beacon Power Corporation's target markets, but are not limited to, factors detailed from time to time in Beacon Power Corporation's filings with the Securities and Exchange Commission.