Tesla battery packs now being sold for home E-storage

Millions of California homeowners and businesses have installed solar panels on their roofs to generate their own electricity. Now a small but growing number of them want to pull the plug on their utilities by storing that energy in batteries and tap that power when the sun isn’t shining. And that has set off a fight over who will ultimately control the state’s power grid—California’s three big monopoly utilities or their customers empowered by companies like SolarCity and Tesla Motors.

SolarCity, the Silicon Valley solar installer, has quietly begun to offer some homeowners a lithium-ion battery pack made by electric carmaker Tesla to store electricity generated by their rooftop photovoltaic arrays. Stem, another Silicon Valley company, will sell or lease a $100,000, 54-kilowatt-hour battery pack to businesses so they can arbitrage the grid by storing electricity when rates are cheap and then using that energy when they’re high.

The state’s utilities, however, are refusing to hook up solar-powered batteries and other home energy storage systems to the grid without charging connection fees that can run $800 or more. Pacific Gas & Electric, Southern California Edison and San Diego Gas & Electric argue that homeowners that cut the cord will saddle other customers with the cost of maintaining the transmission system. (In a preliminary ruling issued in October, regulators ordered the utilities to connect solar battery systems for free while the issue is sorted out.)

But SolarCity customers like Marco Krapels pose a far more existential threat to a century-old power system. Six years ago Krapels put a 2.4-kilowatt solar panel array on the roof of his Marin County, California home. Last April, SolarCity installed a 10-kilowatt-hour Tesla battery in his garage to store electricity generated by the panels. “I should technically be able to function with solar and just the battery indefinitely as long as the sun shines,” Krapels, a renewable energy financer, told me as he stood by his Tesla Model S electric sports sedan. “I don’t want to have to buy power from PG&E at peak rates, I want to use my own power. You see this power line going from the street to my house? I look forward to the day when I cut that wire.”

It certainly makes economic sense for Krapels to do that, especially as a hedge against rising electricity rates. State subsidies pay 60% of the cost of the Tesla battery and Krapels leases the system for less than $40 a month. That’s even less than his lease payments to SolarCity for his solar array. So far SolarCity has signed up more than 300 customers for its solar battery system, according to Peter Rive, the company’s co-founder. As of July 1, there were 667 applications for energy storage systems in California that could store 33 megawatts of electricity, according to the state Public Utilities Commission.

So just how much a threat do SolarCity and Tesla pose to utility hegemony? Time will tell but a look at the companies combined market cap compared to those of the parent companies of California’s Big Three utilities should give utility executives pause. So should the fact that a Tesla Model S battery pack can store six to eight times the electricity of the Tesla home unit. It’s relatively simple to engineer car batteries to store solar electricity and provide power to a home on demand, say at night, when the car is parked in the garage.

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..... Stem, another Silicon Valley company, will sell or lease a $100,000, 54-kilowatt-hour battery pack....

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Nissan is taking its electric vehicle to the next level, pioneering a new system that will enable companies to regulate their electricity bills by tapping into the electric vehicles their employees are driving to work.

The “Vehicle-To-Building” technology allows up to six Nissan Leafs to be connected to an office building’s power distribution board, the Daily Fusion reported. At peak hours, when energy demand is at its highest and electricity is most expensive, the building draws power from the cars. When demand slows and electricity is cheaper, it flows the other way. No matter how much electricity they provide, the system ensures the Nissan Leafs are fully charged by the end of the day for their owners to drive home.

The U.S. military has a pilot program in place that tries out this kind of system, known as vehicle-to-grid, on several domestic bases using its growing fleet of electric vehicles. It earned more than enough revenue to cover the cost of leases for electric vehicles, while providing reliability and secure power backup.

Nissan has conducted a successful field test of the Vehicle-To-Building system and has been using it at the company’s Advanced Technology Center in Atsugi City, Japan since July. According to the Daily Fusion, “the facility benefited from a reduction of 25.6 kW during peak summer periods by controlling the charging time of the electric cars, with no impact on the workers’ daily commute.”

And the results have been significant. The facility achieved a “2.5 percent reduction of electrical power use during peak hours, a saving of nearly 500,000 Yen (approx. $4,900) per year in electrical power cost (based on current Tokyo Electric Power Company’s rates).”

Nissan’s latest endeavor is an offshoot of its “Leaf-To-Home” system, which helps stabilize the electrical grid by charging the vehicle at night, when energy demand is low, or with electricity provided by solar panels. Additionally, it “can be used as back-up power source in emergency situations if there are power outages and/or shortages by providing the stored electricity held in the Nissan Leaf’s onboard batteries,” according to Green Car Congress.

Improving energy storage is critical to fostering the growth of renewable energy. As more renewable energy systems are added to the electrical grid, they need to be supported by better energy storage systems — and that’s where technologies like the Nissan battery can play a key role. And after a price cut of $6,400 earlier this year, the company is striving to make the emissions-free vehicle (and its cutting-edge technology) more accessible to consumers.

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spinningmagnets said:

For a home or apartment building, i had read some things a while back indicating that a vanadium redox liquid flow battery would work well, but...I haven't found anyone who is posting about doing that.

There must be a reason why not, or a better option cost/performance wise...

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