Can the lowly residential electrical panel become the hub of the solar-roofed, battery-backed, EV-equipped smart home? Arch Rao, CEO of Span.IO, thinks so.
The former head of Tesla’s energy storage business, Rao spent years integrating Powerwall batteries, rooftop solar inverters and other distributed energy resources (DERs) with the ubiquitous gray boxes that connect household circuits to incoming grid power.
“It’s easy to recognize why the panel is a critical piece of infrastructure. It connects everything,” Rao said. “But that panel is still sort of antiquated. We’re re-architecting it from scratch to be a much more capable device — not to be just a passive current protection device, but more of a multiplexer, an [input/output, or I/O] for energy and data.”
On Thursday, the San Francisco startup unveiled its flagship product, the Span panel. From the outside, it resembles an oversized white glass-and-metal smartphone mounted on the wall. Inside are the power electronics, sensors, processing power and software to monitor and control up to 32 household circuits, plus solar or battery inverters, EV charger controls, and grid connect-disconnect, all via smartphone app.
This is light-years more functionality than today’s dumb electromechanical panels can provide, of course. But it’s also better than the solutions that DER integrators must today cobble together from disparate parts if they want to give homeowners more sophisticated ways to manage their solar and battery power alongside their household loads.
These are the customers Span is targeting for its initial rollout in California and Hawaii this year, working with “select market leaders” in the residential solar field. The first is Honolulu-based Revolusun, a leading solar-storage installer in Hawaii. "I've been waiting for a product like this for years,” Revolusun CEO Josh Powell said. "It’s going to look better, perform better for homeowners, and simplify everything we do as installers both today and for retrofits down the line.”
While Rao wouldn’t name other potential installer partners, it’s notable that Span’s executive staff includes a Tesla veteran, as well as Colin Law, Span’s head of partnerships, who formerly served as Sunrun’s director of energy services partnerships.
Likewise, Span is working with solar inverter, battery and EV charger manufacturers to integrate their equipment with Span’s controls and application platforms. While Rao declined to name those manufacturers, the demonstration he offered at Span’s office included an LG Chem wall-mount battery.
As for the overriding question of how the high-tech panels will compete with their cheaper analog cousins, Span is targeting an upfront installation cost on par with the typical cost of a main panel upgrade required when solar, batteries or EV chargers are added to a home, or about $2,500, Rao said. With this, Span's installations are cost-advantaged even before the advanced functionality is taken into account.
“The combination of the material cost reduction, but more importantly, the significant reduction in labor cost, is what allows us to get to cost parity. And that’s just cost parity on the hardware and installation,” he said.
“When you include the software functionality we bring in, we’re way cheaper.”
While Span plans to produce "single-digit thousands" of units for its deployment partners next year, that figure could grow to hundreds of thousands in the years to come, he said.
The electrical panel: Past, present, future
Rao left Tesla last year to found Span, and in December raised a “mid-single-digit millions” seed round from investors including Wireframe Ventures, Congruent Ventures, Energy Foundry, Ulu Ventures, Hardware Club, 1/0 Capital, and Wells Fargo Strategic Capital.
All the while, he and his partners were looking for patent filings and other intellectual property from others chasing the same high-tech electric panel concept. While there are many different versions of the idea for controlling commercial and industrial loads, on the residential side, “we haven’t found anything,” he said.
That might be because the electric panel is a commodity piece of equipment, made by a handful of electrical equipment giants like Eaton and Schneider Electric’s Square D. While these companies have experimented with “smart circuit breakers,” they have little incentive to challenge their distributor and contractor customers with a more expensive product.
What's more, the standard electrical panel does a fine job for most homes. But most homes adding DERs find their original panels need an upgrade, along with new equipment such as automated transfer switches and isolation transformers. Years at Tesla’s Powerwall business gave Rao an intimate understanding of the costs and complications of these upgrades.
It also gave him the insight that the electrical panel was the natural point for pre-integrating these technologies, rather than the inverters that have become the default central control nodes for most residential solar-storage systems to date, he said. The Span panel has integrated key solar inverter communications and control standards such as IEEE 1547 to ensure that it can disconnect during grid outages and serve other critical tasks.
But where Span’s panel really outpaces inverters is its ability to monitor, analyze and control each individual household circuit, he said. This includes sensors collecting voltage, current and frequency data at kilohertz resolution, as well as actuators that can disconnect and connect each circuit via homeowner command or automated presets.
Outside of attaching current transformer clamps to every circuit, this level of data granularity is very hard to collect, he said. Energy disaggregation devices from startups like Sense can make do with induction clamps on a home’s electrical mains, but with a loss in accuracy and certainty of measurement, he said. But for the electrical panel, it’s a simple task.
This opens up a world of visibility and control that might otherwise be lost to solar-battery systems trying to manage household loads in relation to the home’s mix of grid-supplied and self-supplied electricity.
Take the example of setting up a solar-battery system to back up critical loads during a grid outage. Today, this involves asking the homeowner to preselect and hard-wire critical loads to be powered by battery, with little control over their electricity consumption beyond turning them on and off.
With the Span panel and app, by contrast, homeowners can pick and choose individual circuits as “must-have” or “nice to have” loads during an outage, preset which ones shut down as battery life is depleted, or control them on the fly from their smartphones.
And because the Span panel has been collecting circuit-level data for months or years before the blackout occurs, it can predict how much electricity those loads are likely to consume in the hours ahead, as well as directly monitor their current usage.
“Nobody does that today — not even Tesla. We ended up falling back and saying, ‘We’ll just show remaining battery life,’” he said. But this kind of vague estimation will become less and less acceptable as DERs become a central part of more homes.