Review: Span Smart Electrical Panel

As part of my recently published year-long quest for energy resilience, wherein I documented my quest to install solar power and a backup battery to power my home, I expressed more than a little disappointment with some aspects of the process and the results. To wit: The battery can only power a small number of “critical loads.” There’s no way to change these loads since they’re hard-wired. The inverter’s app offers poor visibility into the total power consumption of the home. And I’m not really saving very much money.

Shortly after the story ran, I received an interesting email. What if the solution to all (or at least most) of these problems could be found in the one part of my home’s electrical system that hadn’t been upgraded: the circuit breaker?

Arch Rao is a former head of engineering at Tesla Energy, and he’s now the CEO of a company called Span, which he founded in 2018. His company produces one product: a smart electrical panel that brings intelligence to the power generation and consumption of your entire home.

Electrical panels haven’t changed fundamentally since the 1960s, when circuit breakers began replacing fuses. They are “dumb” tech because they are really designed purely for safety. If a circuit is overloaded, it’s the breaker’s job to shut it down. But there’s a ton of information in the power flowing back and forth through those wires, and it’s Span’s idea to give consumers the ability to capture—and control—all of it. As such, Rao offered to install a Span panel in my home so I could see for myself exactly what I was missing, and to address those nagging problems I mentioned earlier.

The Span Smart Electrical Panel replaces your existing circuit breaker completely (including any critical load panels). It is a large (49 by 17 inches) metal box that is considerably bigger than any home electrical panel I’ve encountered, but much more attractive, complete with a snazzy glass door and lights that automatically switch on when the door is opened. Inside the panel the usual columns of plastic breaker switches fill the space, and each circuit can still be turned on or off manually. The real intelligence is in the Span mobile app—but before I could start using that, I had to get the panel installed.

As you might expect, upgrading your home’s electrical panel is not exactly a DIY affair. Span starts by having you take photos of all of your electrical gear, then discuss the install process with a rep over a video chat. From there, a site visit is performed, and the installation is scheduled if everything looks good. I was quoted an estimate of five to seven hours for the installation; my home is large, but our electrical is fairly straightforward. When the appointed day arrived, the installation crew arrived on time, ready to work. Naturally my home was without power during the day, but Span’s crew bought big portable batteries so I could run my router, refrigerator, and other essentials. They even offered to buy me lunch, since I needed to be on site for most of the process in order to answer questions about the various circuits and how to configure them. While the installation ended up running about nine hours, the team was professional and clearly knowledgeable, and a few days later Span dispatched a handyman to patch up the holes in the drywall that were left behind.

After a quick training session, I was left to start working with the system directly. It didn’t take long to see exactly how much I had been missing. The primary screen within the app shows where power is coming from (solar, battery, or grid), and where it’s going (to the home, back to the battery, or back to the grid), all in real time. From there, it’s easy to drill down and get insights into (almost) every circuit in my home, detailing each circuit’s current power draw and, as time went on, how much power each circuit is eating up.

But information like this is only the start. Span is also designed to give you an incredible amount of control over how your battery is used, letting you categorize each circuit among three priority levels: Must have, Nice to have, and Not essential. If the power goes out, the Not essential circuits go dark, the Nice to haves run until the battery hits 50 percent capacity, and the Must haves stay on until the battery’s dead. With my old setup, circuits were either Must have or Not essential—and, critically, there was no way to change them. Now, swapping circuits among these three groups is literally a drag-and-drop operation in the app.

Why is this important? During my initial battery installation, my installer suggested we put the furnace blower on the backup circuit, so we could continue to have heat if the power was cut. It was a nice idea, but I soon found that this one circuit ate up so much power that it drained the battery in less than two hours—a big problem if the power goes out when the sun’s not out to recharge it. But there was no way to correct this. If the power was cut and I happened to be awake, I began manually shutting off that circuit altogether in order to keep the battery from draining too quickly. Without Span, I’d have needed to hire an electrician to fix this issue. With Span, correcting this mistake was trivial. Another nice feature: The app offers on-the-fly estimates of how long the battery will last in the event of an outage, so you can see the likely effect of changes to your priority levels.

Also, backup priorities tend to change. When we first installed our battery, pre-pandemic routines meant I was the only one working from home. Now my wife and our son are here full time, but their workspaces were not initially part of our critical loads. What happens when my daughter is home from college for the summer? Or if we move the router? Or remodel? With Span, it’s easy to make priority changes on the fly, and I find it’s something I tinker with surprisingly often.

What’s especially cool about Span is that, without a critical load panel, the entire house can effectively run off the battery, at least for a while. The reason for a critical load panel in part is that a battery inverter can only handle so much amperage—23 amps, in my case—but Span allows you to ignore this limitation. Its built-in logic ensures the inverter doesn’t get overloaded, and it uses your priority selections to gently shut down circuits if you start to get close to the limit. I haven’t experienced any overloads in my testing to date.

Again, Span provides detailed information about all of this, so I know how much juice my son’s gaming PC and Xbox are eating up (14 kWh each week), and whether our new washer and dryer are more efficient than the old ones they replaced (they’re not). And while you can turn circuits on and off through the physical breakers, you can also do so through the app: If my son doesn’t do his chores, I can shut off the electricity to his room without getting off the couch. That’s parenting, folks.

Is there anything Span can’t do? It’s not a perfect system, and some caveats are worth thinking about.

Foremost (for me) is the physical circuit limit in the Span box. 32 circuits sound like a lot, but the 40 I had in my home meant that a number of circuits had to be doubled up, with two breakers per slot. There’s nothing dangerous or unusual about this, but it does mean the app treats those doubled-up circuits as if they’re a single room. That reduces both control and visibility—my wife’s office is bundled with a largely empty guest room—and it makes for lengthy circuit labels that are difficult to read in the app. This issue can be mitigated with some careful attention to your setup, but unless Span ups the circuit limit at the hardware level, there’s no real way around this. (This issue was compounded by the problem that many of my circuits were misidentified after the original installation; I spent a weekend trying to suss out what was what and relabeling a good portion of the circuits in the app to clean things up.)

Another big challenge is that communication between Span and my inverter isn’t perfect. They do talk—a wire had to be run between the two devices—but Span can’t control the inverter’s settings. I can easily change where the battery power is routed, but if I want to change when the battery runs and how much it’s allowed to drain, I have to use the inverter’s app. Also, since there’s no longer a critical load panel for the battery to supply, the inverter app no longer reports power draw correctly. And the two apps tend to disagree when it comes to solar production: On a recent afternoon, my inverter said I was producing 2.3 kW, while Span said it was just 1.8 kW. It’s all a little sloppy for now, but there’s at least hope that firmware updates and app tweaks (on both sides) could improve things over time. Rao notes that a variety of new features are in the works for Span, including Alexa integration. I look forward to shutting down my son’s room via voice.

Finally, let’s talk price. You know this is not going to be cheap. While the cost varies based on the complexity of the installation, Span says that $6,000 to $7,500 is typical. The good news is that if you install Span as part of a solar-battery upgrade, you can include it in the total cost of your installation, which is then eligible for federal tax credits (a moving target, but 22 percent of the total cost, as of this writing).

Despite some minor flaws, I love the system. It’s a long-overdue, borderline genius product that stands to shake up a decidedly dull, stodgy industry and puts much-needed control back into the hands of homeowners. If you don’t have a battery backup system, however, its utility and value are going to be a lot more limited. If you just want whole-house insight into your electrical usage, add-on systems like Emporia Energy and Sense can get you most of the way for a whole lot less, though they lack controllability features. However, if, like me, you have a solar-battery combo at home, you’ll probably find Span surprisingly hard to live without.

Disclosure: Span installed my equipment for a nominal fee, and since it’s now permanently affixed to my home, there will be no way to return it after this review.