California leads the nation in rooftop solar panels, which means it may soon start leading the nation in the technologies that integrate that solar into the grid — like batteries, if they can do it at the right price.
That’s the test that Greensmith Energy Management Systems will be taking on a megawatt scale soon. The Bethesda, Md.-based startup makes software and hardware for managing batteries and their connection to the grid, including several solar-balancing projects with the likes of Hawaii Electric Co., Carolina utility Progress Energy (now part of Duke Energy), and big Southeast utility Southern Co.
Another, a 50-kilowatt, 82-kilowatt-hour project with solar-rich utility San Diego Gas & Electric, appears to have proven itself ready for a second, bigger phase. Greensmith CEO John Jung told me in an interview last week that the company is now hooking up 1.5 megawatts of grid-balancing lithium-ion batteries, set up in five 300 kilowatt-hour units, for SDG&E some time this fall.
Greensmith will provide the underlying management software, and is in charge of sourcing the batteries and other systems for the project, which hasn’t been officially announced by SD&E, Jung said. While it’s not the biggest grid energy storage project in California, it’s among the biggest specifically aimed at managing solar power fluctuations.
Just how much energy storage California will need to achieve its goal of getting a third of its energy from renewable sources by 2020 is a matter of some debate. The vast majority of that renewable power will come in the form of wind and solar, which are both intermittent in nature.
As these technologies grow into double-digit penetration on the grid, they’re expected to need careful management by utilities seeking to balance them. While weather and load forecasting, smart inverters, demand response and other smart grid-enabled technologies can handle some of the intermittency, much of it must be backed up with real power, either with natural gas-fired peaker plants or with energy storage.
Natural gas is now cheap, and batteries are still too expensive to compete with it, except in a few rare cases where putting in a battery is cheaper than the alternative of, say, building new power lines or commissioning a new coal plant. Wind energy is the biggest user of battery grid storage, whether it’s sodium-sulfur batteries, lithium-ion, flow batteries, Xtreme Power’s solid-state lead-acid battery technology.
But solar power hasn’t seen as much of a corresponding demand for energy storage — perhaps because so much of it is distributed across millions of rooftops. Still, we’re seeing lots of pilot projects, particularly in California.