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November 29, 2019

A recent Greentech Media article brought to light new details about a lithium battery fire at the Arizona Public Service (APS) McMicken Energy Storage facility that occurred in April.

According to GTM, the fire involved a thermal event affecting one battery rack but not a thermal runaway event affecting multiple battery racks. This is very good news, as we’ll explain below. The article also suggests that venting energy storage enclosures to release combustible gases may be a solution. We respectfully disagree.

A few months after the fire, we gave some initial suggestions on how project managers can design risk out of energy storage systems. This post presents our take on the facts as we now understand them.

We still don’t know the root cause of the fire. However, we know enough to conclude that more ventilation is not the best approach to battery fire prevention. We also know that storage projects need a failure plan, and they need to comply with higher standards.

Read on for our recommendations to help energy storage contractors prevent lithium battery fires.

No thermal runaway

After the Arizona fire, an investigation from APS and battery provider Fluence found that only one battery rack containing 14 modules had “melted.” Evidently the fire did not spread to adjacent racks, setting up a more hazardous thermal runaway scenario, which could have added to the fire’s propagation many times over.

This is encouraging. It’s not the failure of a single cell, but rather the propagation of that failed cell that causes all the damage we see in lithium fires. We should understand why the propagation stopped at the rack level. Here are a few possibilities.

(A) The spacing between racks in the system design was wide enough to stop the fire’s propagation in other racks.

(B) The original equipment manufacturer’s design of the battery pack itself helped prevent rack-to-rack propagation.

As the investigation proceeds, we hope to understand not only the root cause of the APS fire but also the design criteria that helped prevent rack-to-rack thermal runaway. APS is reporting investigation updates here. Independent research and third-party lab testing can also produce findings that improve design and engineering for battery safety.

Venting is not the answer

APS director of technology innovation and integration Scott Bordenkircher told GTM that the McMicken facility fire will prompt engineering and design changes, balancing fire suppression with the removal of explosive gases.

A better answer might be to make sure fire response professionals do not open containers designed to enclose and isolate what’s inside. Do we know enough today to arm firefighters with the correct training to protect themselves and suppress fire? A system designed to fully contain explosive gases may be part of the solution rather than the problem. While investigating ways to improve lithium battery safety, it’s also a good idea to explore best practices for first responders.

Root cause unknown

While it is encouraging that rack-to-rack propagation did not occur, the root cause of the APS fire is still unknown. A root cause analysis will help engineers modify future designs to improve lithium battery safety. Following the chain of events backwards to the point of origin (modules within the rack, cells within the module, and down to the cell level) can yield key insights.

If the root cause of the fire was truly “spontaneous,” which is a real possibility when large quantities of lithium cells are manufactured, no design or manufacturing changes can eliminate the possibility of another freak accident occurring. We may have to accept that spontaneous lithium failures are inherent in lithium technology and manufacturing processes. If this is the case, the best we can do is focus on controllable areas of fire suppression, isolation, and safety at the component- and system-level, rather than at the cell- or module-level.

With that in mind, what can energy storage companies do to eliminate or mitigate lithium battery fires? Here are two recommendations.

Plan for failure

In the event of a lithium battery fire, projects need clear and well-documented protocols to assist in fire suppression, cleanup, and investigation. These prevention and remediation plans ought to be provided as part of the project-specific safety plan or permitting process. This would ensure the information is provided to local authorities and site personnel. System design should also be informed by the possibility of system-level or component-level failures. Fire, building, chemical, and electrical safety codes and standards may be consulted and referenced.

For instance, in the APS fire, the bad rack was positioned in the middle of several batteries that maintained a 90% state of charge. As a result, the APS/Fluence team spent 9 weeks removing and de-energizing all of those batteries.

“There was absolutely no playbook,” Bordenkircher told GTM. 

If this experience leads to the creation of a proactive project failure plan, that would be a positive outcome. It could help guide future safety code iterations and standards development.

In addition, it is interesting that APS used LG Chem batteries. According to SepiSolar research, LG Chem batteries have among the widest temperature range needed to initiate thermal runaway. LG Chem batteries also have a fire incident history that reportedly led the battery maker to shut down some of its own storage systems in South Korea.

Raise project standards

The risk of a lithium battery fire is lower in residential and commercial applications than in utility installations. The reason: such projects must comply with the UL 9540 and NFPA 855 safety standards. Utility projects, on the other hand, are basically self-regulating.

UL 9540 addresses construction, performance, and testing of energy storage systems, including how the system handles combustible concentrations and fire detection and suppression.

If we hold utility projects to higher safety standards, battery fire risks will go down.

Improve risk management

It’s more important than ever to understand and manage the risks associated with energy storage projects. That’s why SepiSolar is writing about the APS battery fire and why we will continue to write about it.

Our experience balancing cost, speed, and safety in energy storage projects contributed to the development of the new C&I Project Risk Management Guide. Download a free copy today.

Feature photo by Constante Ken Lim.

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November 1, 2019

Raise your hand if you’re suffering from too much time and not enough email. Need a second to think about it? Nah, didn’t think so.

This question came up several times as we started developing a newsletter for the people we work with who lead solar, storage and microgrid projects in the commercial and industrial market. We’re pretty sure you didn’t wake up this morning wondering how to fill your time and hoping for a little more email to click on.

We’re all busy. To stay informed, you might read a few articles in the industry press or attend a few conferences and events throughout the year. But the process is inefficient. You might sift through dozens of headlines to find the ones that matter. It can also be expensive. Traveling to a conference can easily cost $1,000 per person or more.

Wouldn’t it be nice to get a concise email once a month that’s filled exclusively with information about C&I projects?

We think so too. That’s why we’re launching SepiSolar’s monthly C&I project newsletter.

The first edition will be published in November. Become one of our first free subscribers. Sign up now.



Why subscribe?

News providers used to try and be everything to everyone. The New York Times still claims to publish “all the news that’s fit to print.” You can buy a plain sweatshirt with the slogan printed in a small box for $85. Any size you like.

A lot of company newsletters fall short for another reason, because they’re too self-promotional. Five years ago, a service that helps people unsubscribe from email lists called Unroll.me published a list of the email newsletters with the highest opt-out rates. The flower delivery service 1800 Flowers topped the charts with a 52.5 percent unsubscribe rate. More than half of subscribers wanted out.

We value your time. So let’s be clear from the start. If you are not a project manager, the head of operations, or an executive who leads solar, storage, or microgrid projects for C&I customers, the C&I project newsletter probably isn’t for you.

However, if you’d like to hear about new ideas in permitting, interconnection, project design and engineering, and more, we think you’ve come to the right place.

In SepiSolar’s C&I project newsletter, you’ll find original content created through a collaboration between our professional engineering and technical sales, who assure that you’re getting high-quality, authentic information, and our communications team, who head up content planning, writing and editing.



We want your ideas

In the months ahead, we have a lot of ideas that we’re excited to cover.

  • How to discharge batteries from the customer side of the meter into the grid and collect net energy metering credits.
  • How to resolve the eternal debate over DC coupling versus AC coupling once and for all.
  • What lessons have we learned from the 2019 APS battery fire.

We welcome your ideas! Please contact us to share topics that you’d like us to cover in the C&I project newsletter. Let us know if you’re interested in contributing an article yourself. And once you’ve seen the newsletter, please share feedback.

The Solar Energy Industries Association’s latest Solar Means Business report, published in July, identified over 7 GW of solar projects delivering energy to corporate solar users, up from 2.5 GW of projects that were cited in the prior year’s report. The growth of C&I projects might seem mind blowing, but it’s still just the tip of the iceberg.

Get ready for much more to come from solar, storage and microgrids. Subscribe to the C&I project newsletter today.


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October 16, 2019

Every once in a while, we get a familiar request — a contractor asks to “fast track” a new solar project. We say: Be careful what you wish for. You might just get it.

Our response wasn’t always this way. At one point, customers wouldn’t even have to ask to speed up the design and engineering process. They wanted deliverables quickly — yesterday — and at low cost. We delivered. Sort of.

Soon, we learned that while we could deliver on the front-end, we had too little control over the back-end. We were working too quickly. Customer requests for design changes would come weeks, sometimes months, after delivery of the original plan set. This increased project costs and risk in the long run.

At SepiSolar, we have introduced structure, definition, and organization to the project design and engineering process with discrete handoffs, milestones, stages, and defined activities. We control project costs, timeline, scope, quality, liability, customer success and safety, reducing cost and risk to the project.

We used to try explaining to customers one-by-one why no engineer has the power to expedite projects.

Each project dictates its own timeline according to the project data at hand, the complexity of the project, climate, and other variables that we cannot control. If a commercial property has no as-built plans available, someone needs to conduct a site survey and perform discovery on key aspects of the facility. There are faster ways and slower ways to perform discovery, but you cannot fast-track your way through it.

In other words, the job of the engineer is not to tell the project how much time it has. Rather, we listen and then help the EPC get through it.

Since we have these conversations with some frequency, we decided to take some of our core insights and share them in the C&I Solar Risk Management Guide.


What’s in the risk management guide?

The C&I Solar Risk Management Guide covers the key milestones from starting a project plan set to matching the as-built conditions of a completed project. Milestones include:

  • Project kickoff
  • Preliminary analysis
  • 50% design
  • 90% design
  • Permit plan set
  • Revised permit plan set
  • As-builts

Managing risk means having a clear and complete idea of the scope of work up front and catching all components and elements of design and engineering that need to be specified, budgeted for, and tracked. When changes occur, it is usually due to lack of specificity in the original scope of work, or something that nobody saw coming. Surprises increase cost. We don’t like surprises in construction.

By thoroughly defining the scope of work up front and identifying potential surprises that could come back to bite us, we proceed with projects in stages, never getting too far ahead of ourselves without all the necessary information.

Subway, the fast-food chain, recognizes the value of risk management. At the lunch counter, the selection of bread drives the development of the meal. You might ask for the pit-smoked brisket and then wonder why your server holds still, waiting for you to choose between six-inch and foot-long subs made of Italian bread, whole wheat, or something else. You’re hungry. Can’t they go a little faster?

If the server rushed ahead with the wrong bread, there would be an even longer delay as he builds your sandwich a second time. Bad move. Now you’re really getting hangry. Subway’s process won’t set any sandwich-making speed records. But it’s dependable, time and time again.



How to use the C&I Solar Risk Management Guide

Our goal with the solar risk management guide is twofold. First, we want to point out how engineering and design can have a big impact on project success, even though it accounts for a small share of project costs. Second, we want project and operations managers to know what you can expect from a structured, highly organized project design process.

Have a look at the guide. Download a copy of the project milestones, and share it with your team.

How does your project design process compare to ours? Are we following similar paths? Where are the differences? If you have questions or comments about the C&I Solar Risk Management Guide, join the conversation with us on LinkedIn.


CA Small Business Enterprise

Certification ID:
2015743

Bidder/Supplier ID:
BID0068933

NAICS Codes:
541330 – Engineering services
541340 – Drafting services
541490 – Other specialized design services
541618 – Other management consulting services
541690 – Other scientific and technical consulting services
541990 – All other professional, scientific, and technical services

D-U-N-S number:
065817064
CAGE:
8F5K7

UNSPSC Code:
811024, 81101701, 81101516, 81101604, 43232614, 81101505




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