By Ben Paulos
Resilient home
California is suffering its worst fire season ever, with over 4 million acres burned this year alone. In EBCE’s service area, PG&E is continuing to implement Public Safety Power Shutoff (PSPS) events, proactively shutting off power to thousands of customers to prevent accidental wildfires.
While power shutoff events may reduce community risk to wildfires they can also deeply impact residents and businesses. This is especially true with the most vulnerable customers, such as those that are low-income, elderly, or dependent on powered medical equipment, for whom reliable electricity service can be a matter of life or death.
To help customers prepare for outages, as well as provide services to the grid every day, EBCE has launched the Resilient Home program. Partnering with solar and storage developer Sunrun, the program aims to deploy over 1,000 battery backup systems, with five megawatts of residential storage capacity.
The program also enables residents to share power from their batteries with EBCE when the grid is operating normally. Customers can let Sunrun control their battery to export power to the grid to help manage peak demand, and earn a one-time payment of $1,250.
At least 20% of program installations will be located in disadvantaged and low-income communities, or serve customers on financial assistance programs or reliant on medical equipment. Since the program launched in August more than 700 residents in Alameda County have registered for the Resilient Home program to see if a new solar + battery backup system is a good fit for their home.
The swiss army knife of energy
Batteries are multi-purpose — the Swiss army knife of energy — able to provide a variety of services to the customer as well as to the grid. For the customer, batteries can provide backup power when the grid goes down, shift power from off-peak to on-peak periods to take advantage of lower rates, and cut demand charges for business customers.
For the grid, batteries can provide frequency response (helping the system stay at a steady 60 cycles per second), load following (charging or discharging to help smooth out demand), and capacity. They can also be part of a “mini-grid” or “micro-grid” system, working with solar and other generators to power a building or campus.
The sweet spot is when a battery can provide multiple services. To do this, they have to be located behind the meter, on the customer’s premises. If the grid goes down, the customer can “island” and operate independently. When the grid is up, the batteries can help serve the grid and the customer.
Due to complicated rules about distributed resources, the Resilient Home offering will capture some, but not all of these values. To simplify matters, batteries enrolled in the Resilient Home grid services program will be discharged on a regular schedule every day to help EBCE manage the early evening hours. As the sun goes down, solar output fades, but demand stays high for a while, as air conditioners continue to run and lights come on. The batteries will be set to discharge in that 5:00 to 9:00 pm slot. They will always stay at least 20% charged in case there is an outage at night.
How a solar + storage system can work with a single customer: excess solar generation during the day is stored in the battery until evening, when solar fades. The battery discharges at night to reduce purchases from the grid during peak rate hours.
That time slot also coincides with the customer’s peak energy prices. Many customers (and all solar customers) are on time-of-use rates, with higher prices during peak hours. As their solar output fades at sunset, customers buy power from the grid at prices that are higher until late evening. The battery will discharge then (the yellow region in the figure) reducing consumption from the grid and saving money.
Win-winning with batteries
For EBCE as a whole, the price dynamics are similar, with higher costs in the evening peak hours for both energy and capacity.
All power providers are required to maintain reserves of sufficient capacity, called resource adequacy or RA, to make sure there is enough capacity to meet their demand at all times. They even need to have a little extra, to deal with unexpected demand or grid problems. EBCE contracts with power suppliers, most often using gas-fired power plants, to provide the necessary capacity.
But capacity services can also be supplied by batteries. EBCE has already signed contracts with integrated solar and grid-scale battery systems, to provide wholesale power services, and is partnering on the Oakland Clean Energy Initiative to replace an old power plant in Jack London Square with batteries.
EBCE can count these projects and the Resilient Home batteries against the load forecast filed with the California Energy Commission, reducing the need to buy it from other suppliers. Behind-the-meter batteries are counted as reductions to demand during peak hours.
Counting the RA value of distributed batteries is a win-win proposition that benefits both EBCE’s customers and the grid as a whole, helping keep EBCE’s investments local to create jobs and enhance the resilience of our community.
Even the companies involved are local, as Sunrun is based in San Francisco and the batteries are being provided by Fremont-based Tesla. (Sunrun is also offering smaller batteries from LG Chem, a Korean company, as an option for homeowners interested in partial backup.) Since solar + battery backup systems have vast potential for resilient energy applications all around the world (PDF), EBCE’s Resilient Home is serving as a local proving ground for broad replication.
JP Ross, Vice President of Local Development, Electrification and Innovation for EBCE, says early marketing efforts are going well. “So far we have over 700 eligible registrations and 100 sales in the pipeline, with a goal of 1000 installations,” says Ross.
EBCE is working with its local government partners to conduct outreach to residents, and held virtual workshops in September and October.
“The fire season is well underway, and that is boosting interest,” he adds.
