March 11, 2021: Gridtential Energy and Electric Applications Incorporated will start a new research project on April 1 supported by the Consortium for Battery Innovation to test bipolar batteries for residential energy storage.
Gridtential will supply 24V and 48V 15Ah battery strings for the 15-month project, which will be tested by EAI in a variety of situations typical for power supplied by solar panels to behind-the-meter applications.
The capacity of the advanced lead batteries will vary from 5kWh to 15kWh.
“This is pre-commercial research that will be accessible to all our members,” says Matt Raiford, technical director at the CBI. “But the commercial possibilities are huge.
“Research we’ve been involved in with the Pacific Northwest National Lab shows that at the residential level, lead battery systems are around a third cheaper for energy storage than their lithium counterparts.
“They also have major advantages in terms of safety — an issue both to consumer confidence but also of growing importance to insurance firms — as well as in terms of more straight-forward electronics and installation. And that’s not forgetting that lithium batteries have a very poor recycling rate.”
The residential energy storage market in the US is already booming.
Market analysis firm Wood Mackenzie reckons 430MW was installed last year, more than double that of 2019. It expects this trend to continue.
The advanced batteries made by Gridtential use silicon wafers instead of lead grids as current collectors. This reduces the cost of the lead and shrinks the battery’s size as well as doubles its energy density.
It also boosts the cycle life to between 1,500 and 3,000 cycles compared with a conventional deep cycle lead battery, which offers 400-800. Lithium batteries, however, offer a life cycle of greater than 4,000 cycles at 80% depth of discharge.
EAI testing of the batteries will use the IEC61427 battery standard, a common testing protocol for load lifting from solar applications.
“This project will further the understanding the impact of utilizing high-voltage silicon joule AGM battery strings on cell balance, battery management, charge control, and system integration,” says Gridtential CEO John Barton. “The work will provide valuable insights for field deployment and demonstrate the performance of our batteries in a simulated ESS application. EAI brings expertise in testing batteries and novel approaches of charging lead batteries to extend cycle life.”
EAI will also duplicate the various demand pressures that the batteries will be exposed to at different times and seasons. A lot of research on these stresses has already been done by utilities such as Duke Energy.
One key question is whether the lead battery industry is ready to embark on productization — to find development partners such as designers, installers and manufacturers to advance the deployment of these batteries in residential energy systems of the future. Historically, the industry has been reluctant to leave its comfort zone of just manufacturing batteries and venture into partnerships with applications tied to their use.
“While the scope of this project doesn’t include developing an ESS ‘product, we are also working with a number of system integrators who are excited to see the results with the intention of using those insights in their own implementations,” says Barton. “However, the demand for affordable, fire-safe, behind-the-meter energy storage systems is immense — and with a recyclable battery solution even better.
“Our view at this point is that there is enough distribution of value between the battery, enclosure, BMS/control systems, and installation that the ‘winner’ doesn’t necessarily need to be a battery manufacturer.”
The project is part of CBI’s 2021 research program aimed at enhancing lead battery performance under the banner of energy storage.