Combining batteries, inverters and control systems in modular systems that can be installed and operated in a standard way across multiple sites is an important trend in bringing down the cost and complexity of energy storage. We’ve seen a number of companies roll out their own versions, from Gexpro’s integrated systems for commercial and industrial customers, to Tesla’s smaller-scale Powerwalls and larger-scale Powerpacks, to Schneider Electric’s EcoBlade units built to fit into a server rack-sized space.
On Tuesday, NEC Energy Solutions unveiled its own version of the modular storage system -- the Distributed Energy Storage Solution (DSS). Set for availability in early 2017 in North America and later that year globally, the systems are self-contained in thermally controlled and fire-suppression-equipped enclosures, rated for both outdoor and indoor installation.
The idea, company CEO Bud Collins explained, is to provide an easy-to-use package for thesolarinstallers, energy services companies and other parties that are seeking affordable battery systems that don’t require design and engineering expertise to put to use. “It’s really an energy storage system in a box that comes as a completely configured system,” he said in an interview last week.
The DSS units can be scaled up from 85 kilowatt-hours to 510 kilowatt-hours of energy storage capacity, and between 30 kilowatts to 650 kilowatts of power capacity. NEC Energy Solutions, formed through NEC’s purchase of A123 Systems in 2014, has concentrated on larger, utility-scale systems until now, making the DSS its first product aimed specifically at the non-utility customer.
As Collins said, “We wanted to make the controls, installation and operation so simple that your average three-phase electrician would have no trouble installing it.” The primary target will be companies serving commercial and industrial (C&I) customers' behind-the-meter battery needs.
A new report from GTM Research found the viability of commercial storage for demand-charge management today would depend on areas with a demand charge of $15 per kilowatt per month -- a situation that applies in seven U.S. states currently, but could expand to 19 states by 2021 if battery prices continue to fall as expected. That growth potential has recently drawn a number of new entrants from the residential solar-storage space (Sonnen) and the utility-scale energy storage space (Greensmith), respectively.
As for price, NEC is targeting an end-customer cost of $750 per kilowatt-hour -- “and this is at the retail level,” Collins said. That's to say, it’s a price point the company expects the buyers of the system will be able to offer to the building owners, utilities or other customers they serve.
That’s a different way to measure pricing, compared to the other numbers we’ve seen out there for similar modular battery systems, which makes direct comparison difficult. Schneider Electric’s EcoBlade units are targeting a price of $500 per kilowatt-hour, for example, but that price doesn’t explicitly include some of the components, such as enclosures and fire suppression systems, that NEC is adding into its pricing figure.
On the larger-scale side, Tesla’s Powerpack design page notes that its minimum-size order of 50 kilowatts and 200 kilowatt-hours comes at a total estimated price of $145,100, or about $725 per kilowatt-hour, a price that includes inverters, cabling and site support hardware.
But according to Collins, NEC’s pre-integrated approach is expected to drive down balance-of-system costs that other companies’ configurations may not. That doesn't just include the equipment besides the batteries involved, but also the costs of designing and integrating those components.
“By the time they put in the PCS, the transformer, the fire suppression, someone to put the pieces together and do all the engineering work, all of a sudden you’re over $1,000 per kilowatt-hour,” he said.
As GTM Research notes, balance-of-system costs represent a significant portion of overall grid battery costs, and while these costs are expected to fall by about 40 percent over the next five years, that’s not as steep a price decline as we’re seeing today for underlying lithium-ion batteries.
NEC is also promising that its DSS systems will be capable of cycling its batteries up to 6,000 times without significant degradation of their capacity under a 10-year warranty -- something that not all competing integrated battery systems can offer. “You’ve got to look really hard at the warranties,” he said.
In a first for the company, NEC Energy Solutions will be using lithium-ion batteries from LG Chem, rather than its underlying A123 battery technology, for the DSS units. These LG cells are capable of discharging their energy in about 15 to 20 minutes, or a 4C rating, compared to the typical 2C rating of the Panasonic lithium-ion battery cells used by Tesla, he said. (“C rating” stands for capacity rating, and is a standard metric for measuring a battery’s ability to discharge in a certain period of time.)
These characteristics could allow NEC’s DSS units to be put to use in a wider variety of applications, Roger Lin, director of product marketing, noted. That may be an important characteristic for batteries designed for use by customers that might not be interested in closely monitoring and controlling their operation. “If you use a cell that doesn’t have great durability or cycle life, the sensitivity of that change can open up gaps, where you can’t perform a service.”
The DSS units can be set up to run autonomously of central control, or managed through the company’s AEROS control platform, he said. “We’ve got dispatch algorithms that will sense conditions around it and respond autonomously,” he added. This kind of control capability isn’t unique to NEC, of course. Tesla and Schneider use their own software control platforms to manage their batteries, and Gexpro uses software from startup Geli.
At the same time, “the system has the ability to give its data to a higher-level management system,” he said. “AEROS can tier these things to be managed as a fleet.” That could open up applications for utilities to use the units as part of their grid operations, and “some of the big investor-owned utilities we’ve spoken to are very interested in this kind of standalone energy storage solution,” he added.