by Julian Spector
September 15, 2017

Energy storage is like poker chips: You charge up when you have some extra money in your pocket and discharge when you need that cash back.

Feel free to use that next time you have to explain what you do to some inebriated souls at the craps table past the hour of midnight. The opportunity may have passed, though, because Solar Power International moves from Sin City to Disney City next year. 

Storage made a showing at SPI, like it does at any solar conference these days, but it couldn't help but be overshadowed by the solar industry's struggle for survival against possible trade tariffs from Suniva's Section 201 complaint. 

That threat prompted an unusually brutal smackdown of both Suniva and fellow petitioner SolarWorld by the head of the solar industry group and several major industry leaders at the opening session. This was all the more striking because SolarWorld attended the conference with a sizable booth, complete with flatscreens simply displaying a waving star-spangled banner; it also hosted a boozy afterparty.

There was little to report on the utility-scale solar-plus-storage front, even though all the top players are working on it. The news came more from the residential side, in fact.

Sunrun: 2,000 BrightBox units sold

Sunrun Executive Chairman Ed Fenster confirmed to GTM that the company has sold more than 2,000 of its residential BrightBox solar-plus-storage systems, which averages out to about 20 kilowatt-hours per home. That's twice the sales reported earlier this year.

That quite likely puts the company in the lead for residential storage sales in the U.S. (Sonnen has many times that many sales in Germany). At the very least, I haven't heard another company report more deployments.

The key challenge now, Fenster said, is working out the permitting rules to streamline storage deployment, and that has to happen at a local level in many places.

"Everyone wants it to work, but it's still a regulatory process that takes time," he said. "Just like I bet the people who pioneered net-metering in the '80s killed themselves with each building department and each utility, we're kind of going through that process."

This account of residential storage sales suggests that a step change is coming. It takes a lot of time and effort to muddle through the nitty-gritty of how to get a system permitted with local authorities, but once that's accomplished, it becomes much easier to deploy more units, more rapidly.

It's hard to see sales really taking off without a more pronounced and widespread price signal for homeowners to time-shift their grid consumption, but it sure will help to have the permitting figured out before that arrives.

BYD makes big moves in U.K., enters U.S. resi market

This Chinese battery giant has been steadily growing its empire all over the world. 

The company logged 60 megawatt-hours of storage paired with PV in the United Kingdom. Working with developer Anesco, BYD supplied the batteries across several sites, the largest of which has 10 megawatt-hours.

The pipeline trajectory there is quite staggering, according to Tom Zhao, managing director of global sales in the solar and energy storage division. He said BYD contracted 100 megawatt-hours in the U.K. last year, and expects to contract 150 megawatt-hours this year followed by 800 megawatt-hours next year.

Zhao also shed some light on his company's approach to battery production. It has 16 gigawatt-hours of factory capacity built, and is on the way up to 29 gigawatt-hours. A 1 gigawatt-hour factory line measures approximately 2 kilometers, is fully automated and costs $160 million. It's no wonder the battery manufacturing game is a great-power battle, in which BYD only trails Panasonic; few companies can meet the cost of entry.

BYD also has a residential offering, the B-Box. It's modular and can grow over time -- an approach we've seen from the likes of Mercedes-Benz and Enphase. It's expected to make landfall in the U.S. by the end of the year, further expanding the roster of brands chasing the tiny American home storage market.

Sonnen home automation 

Sonnen has been growing into its niche on the premium end of the home storage spectrum, rather than touting cheapness as a main asset the way some folks do. Now the company's pushing that further with a move into home automation.

Home automation, as SVP Blake Richetta described it to me, makes the color-changing LEDs and Nest thermostats look like "smart home Tinkertoys." The vision here is for (affluent) homes to respond automatically when a resident returns home from work, for instance, flipping the temperature to the preferred setting, putting the lights on just right and adjusting the blinds in a holistic domestic ballet. 

Throw in a smart battery system and rooftop solar, and you have a house that not only operates intelligently, but also optimizes those appliances alongside its own energy generation and control. It can track the temperature and shut the blinds to de-stress the air conditioning so the Sonnen system can power the full load through the peak period.

It turns out several of Sonnen's U.S. executives came from careers in home automation. Now they've found partners in the space to develop drivers that will allow those control systems to interact with the Sonnen storage product.

It's unabashedly high-end, but the tech-savvy eco-chic market is a stronghold for Sonnen, and this appears to be a logical extension.

Free storage-sizing tool for urban resilience

Cities are scrambling to outfit disaster shelters with solar and energy storage (and diesel generators) to provide resilience in the event of disasters like Hurricanes Irma and Harvey. But it's hard for a city bureaucracy to get a handle on how to design systems to meet those needs, given how new and ever-evolving the technology is.

San Francisco's Department of the Environment recently tackled this problem with the help of a Department of Energy SunShot grant. The result: SolarResilient, a free sizing tool that cities and building owners can use to quickly gauge the feasibility of a PV+storage system.

Normally, a city would need to hire a consultant to run a feasibility study like this. Between procuring the funds, getting approval and waiting for the analysis to be done, that can easily take three months, said Jessica Tse, distributed energy resources coordinator at the department. At that point, all that trouble may just conclude with the finding that a building isn't suited for the project.

Now, building managers can use SolarResilient to input data like square footage of roof and parking lot, typical load, percentage of typical load desired for emergency backup, type of battery, type of solar modules and the presence of existing solar or diesel generation.

The system generates solar and storage configurations, and says whether or not they're feasible given the space available. If the answer is yes, the user can take the results to a developer, who can discuss costs and refine the design.

"You’re eliminating that long lead time to even pitch the idea and look for funding internally," Tse said. "It’s free, so it doesn’t hurt to get that initial data point."

The grant wraps up at the end of the year. At that point, the city's servers will continue to host the service, but the creators are hoping to find a new funding source to keep it updated with the latest solar and storage advances.