Innovator Tesla's Powerwall home energy battery storage systems made a big splash a few weeks ago, promising a win-win exchange of power between homes and utilities. The trick was to develop batteries that could be recharged repeatedly for years and store up enough of a charge to power the energy-needs of a home for an acceptable length of hours before it would need to be replenished.
Solar power--like wind--is fine for what it is as a net energy and cost saver. Where solar--again, like wind--falls short is that, yes, it's renewable, but it's also intermittent. Importantly, when a home or a community is capable of feeding power to the grid, and when it needs to draw from the grid is a factor of nature, and therefore uncontrollable, and therefore, inefficient.
Battery storage solves for that, because it allows a home or neighborhood to feed or draw in a cadenced, real-time way that responds to when prices are best, energy use peaks, even when electrons are "cleanest."
Its $3,000 Powerwall system, the Tesla site says, will be ready for delivery "this summer." People can sign up to be one of the first customers.
But did you know there are homes, and now even an entire cluster of homes in a neighborhood in Southern California, already availing of the advantages of battery-powered home energy storage?
Almost 18 months ago, Honda and the University of California, Davis, unveiled its battery-powered energy "smart home" in Davis, spotlighting the convergence between transportation and buildings as contributors to a reported 44% of U.S. greenhouse gas emissions.
At the time, New York Times staffer Todd Woody reported:
The heart of Honda’s 1,944-square-foot home is a room off the spotless garage that contains a 10 kilowatt-hour lithium-ion battery pack housed in a black box. The battery is a smaller version of the one that powers the all-electric Honda Fit parked nearby.
Next to the battery pack sits a bigger white box called the Home Energy Management System. It is the brains of the house, deciding when to tap renewable electricity generated by a 9.5-kilowatt solar panel array installed on the home’s roof to charge the car’s battery or store the solar energy.
Not long after the Honda home came to light, two of high volume home building's early adopters, KB Home and Meritage Homes began to explore battery storage at an individual home scale as part of their solar and net zero energy strategies, which are to stay both in home building's vanguard and ahead-of-the-code, particularly in California, which calls for all new homes to be net zero energy by 2030.
KB began leveraging its relationship with solar provider SunPower in June of last year, piloting its residential energy management and battery storage systems in select KB Home communities in Irvine, El Dorado Hills, and San Diego, Calif.
KB Home, “estimates that at current residential electric rates, a 1.4-kilowatt high-efficiency photovoltaic system provided by SunPower and installed as a standard part of a 3,654-square-foot, ENERGY STAR® certified home at Vicenza would yield average energy savings of $216 per month, or approximately $25,900 over ten years, compared to a typical resale home without these features.”
Then, this year on Earth Day, Meritage took the wraps off its Sierra Crest, (Fontana, Calif.) program for 20 "entry-level" homes, which is the first "community-scale" roll-out of battery-powered homes as part of its own Net Zero and Zero Energy Ready homes programs.
Here's a brief take on the Sierra Crest program from Meritage VP, environmental affairs, CR Herro, as quoted by CleanTechnica:
There are several ZNE homes throughout California, but none clustered at one community. This community not only allows the value of operation cost reduction to the homeowners, but provides much-needed data to the utilities about kW production and demand at each home, and cumulatively at the transformer level to provide needed data to design service for community level Zero Energy as California building code progresses toward this standard.
Renewable Energy World.com's Junko Movellan also pointed up some noteworthy aspects of the Meritage/SunPower program:
The ZNE homes, which are currently in development in Sierra Crest Community, will include high-efficiency solar photovoltaic (PV), HVAC systems, water heating equipment, heat pumps and integrated fresh air ventilation. In addition, each will have spray foam insulation, highly insulated windows, energy-efficient lighting, smart chargers and smart appliances.
With these technologies, the ZHE homes are projected to curb energy use by as much as 60 percent compared to a house built to the latest California Energy Code. One added energy efficiency bonus is its ability to downsize on-site solar capacity. “In a conventional home, the size of PV, which is sufficient to make a home Zero Energy, can be between 7 kW and 10 kW. Because of the included advanced energy efficiency, our ZNE homes can achieve Zero Energy with 3.5 to 4.5 kW,” commented Herro.
CR and I spoke briefly about the program last night, as I learned that he will be a keynote presenter as part of the 2015 Avid Conference, a three-day dive into home building innovation and excellence, set to take place next week.
"There's a net zero energy level we can achieve in homes through work on our supply chain and in our building systems, and that's relatively easy to accomplish at the household scale," Herro told me. "It's at the utility level, where if we get net zero energy right, we can save billions and billions of dollars and the equivalent in energy savings, that's potentially the value of this program."
Here are a few data points Herro will share and comment on in next week's Avid conference. The conference is August 12-14, in Madison, Wisc.
Sierra Crest :
· Total Lots: 187 for community, 20 for NZE homes
· There are two parallel promotions – the first is that the Zero Energy Package is available AT NO COST to the homebuyer on these twenty homes AND a Zero Energy Package is available throughout the community at a discounted rate
· Total Lots available
o Grand Canyon Collection 9 NZE Homes total
§ 1,936 - 2,319 sq. ft
§ $378,990 - $402,990
o Yosemite Collection 11 NZE Homes total
§ 2,673 - 2,915 sq. ft.
§ $413,990 - $431,990
o Rocky Mountain Collection NZE not offered standard on these lots. Would be an option cost. We are offering solar standard for the month of April.
§ 3,066 - 3,700 sq. ft.
§ $442,990 - $481,990
· In a conventional home, PV sufficient to make a home Zero Energy can be between 7kW and 10kW. Because of the included advanced energy efficiency (included Spray Foam insulation, heat pump water heating, LED Lights, and efficient HVAC and appliances) These 1900 to 2900 sf homes achieve Zero Energy with 3.5 to 4.5 kW
For more information on the 2015 Avid Conference, click here. Fix your divots.