The Rapid Rise of Residential Energy Storage

Energy storage is heralded as the critical technology that will make widespread adoption of renewable energy possible. Storage bottles sunlight, addressing a key drawback to solar energy — that it can’t provide electricity when the sun isn’t shining. Energy storage also cures additional utility ailments from grid resiliency to power smoothing.

Due to a rise in incentives and a drop in storage costs, the market for this storage is heating up in the U.S. The market is expected to grow 250 percent just this year.

California is leading the energy storage market thanks to Assembly Bill 2514, which requires state utilities to procure 1.3 GW of storage by 2020. Now California’s three largest investor-owned utilities, Southern California Edison (SCE), Pacific Gas and Electric (PG&E) and San Diego Gas & Electric, are installing cost-effective storage solutions. SCE, for example, invested in a wind farm in the Mojave Desert equipped with giant lithium-ion batteries. The East Coast is following California’s example. New York recently budgeted $25 million to promote storage development.

While the utility-scale market gets most of the attention, a quietly growing storage market segment with a lot of potential is residential solar. After all, residential solar is a fast growing solar market segment — increasing 49 percent in 2014. Unsurprisingly it offers immense opportunity for storage.

Residential PV panels produce ample electricity for customers when the sun is shining, but on cloudy days and at night energy generation is low. Saving a surplus of solar energy from times of peak sunlight helps consumers maximize their consumption of self-generated power. This is particularly appealing and important in states where net metering is either unappealing economically or prohibited, meaning homeowners cannot sell their surplus solar energy back to the grid. Arizona is a state where storage solutions are that much more appealing because net metering is coupled with a fee.

Areas with high amounts of residential solar penetration can put a strain traditional utility power supply controls, causing voltage disturbances and other power quality concerns. Residential energy storage can help regulate the power supply and smooth the quantity of electricity sold back to the grid. This is critical in markets like Hawaii, where one out of nine homes is equipped with a solar PV system, according to U.S. Energy Information Administration.

Energy storage can also provide back-up power in case of an emergency, like natural disasters that may damage power lines and cut off the electricity supply. During Hurricane Sandy, thousands of solar systems sat idle, unable to provide electricity without connection to the grid. With storage, those solar systems could have provided much needed off-grid support.

Traditionally, energy storage solutions have required a lot of space. For example pumped storage, an effective and historically popular technology, can only integrate with large utility-scale power generation, like dams. Flywheels, which utilize a quickly spinning rotor to store energy, also require more space and typically available for residential solar systems. With advancements in electric vehicle technology the cost of more compact lithium-ion batteries has fallen dramatically. The size of these batteries is perfectly suited for residential PV systems.

Many market players are eager to capitalize on the growing residential solar market. Just last month, Tesla unveiled its residential storage unit and announced partnerships with solar companies SolarCity and Sunrun. Sungevity teamed up with Sonnenbatterie and Trina Solar to launch its own residential battery. In Europe, Mercedes-Benz released a storage solution for residential and commercial applications. Solarwatt, a company owned by a major BMW shareholder, the Quandt family, will also offer a residential behind-the-meter solution. Both Solarwatt and Mercedes-Benz introduced their storage solution this month at electrical energy storage — Europe, collocated with Intersolar Europe.

We’re off to the races with residential energy storage. Experts predict costs will continue to fall, accelerating storage integration with solar systems.

If you’re looking to learn more about energy storage, Intersolar North America (San Francisco from July 14-16) is hosting a new special exhibition, ees (electrical energy storage) to showcase the latest technologies and policies in the energy storage value chain. Intersolar North America also has a special storage conference track for professionals interested in learning the latest insights from leaders in the industry. Hope to see you there.

Lead image: Chart up. Credit: Shutterstock.

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Markus Elsässer is the founder and CEO of Solar Promotion, an internationally operating, private trade fair company with a focus on renewable energy and energy efficiency. Under Markus’s leadership Solar Promotion International’s flagship event series, Intersolar, has grown to become the world´s largest trade fair for solar technologies with over 3,500 exhibitors and 120,000 visitors. Building on Intersolar's success in the European market, Intersolar North America opened in 2008 in San Francisco and became the second exhibition location in the series, followed by Intersolar India and Intersolar China. This year marks the debut of Intersolar's newest conference, Intersolar South America in Sao Paulo. Prior to founding Solar Promotion International, Markus Elsässer worked for a German manufacturer of solar thermal systems. Markus holds a degree in mechanical engineering from the University of Stuttgart in Germany.

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