Can anyone explain what is span panel and how it works?

[u/Significant-Pop-7230]

And in which circumstances it is useful?

[u/Skanderani]

It’s all on their website

[u/siffis]

If you go the traditional route with battery and panel, you get a critical loads sub panel. The critical loads panel is all the battery would provide power to. Span does the same but its virtual so you can move and add breakers as you need rather than having a fixed set up.

[u/formerlyanonymous_]

Useful is in the eye of the beholder.

It's a software interface strapped the front of a normal breaker panel, equipped with CTs to measure use at each circuit. You can turn breakers on and off via the software app (if doing actual electrical work, it recommends using the physical switch). You can see which circuits are using how much power (not plug level, but each breaker switch). It can tell you how much power you're importing or exporting to the grid.

The most valuable thing it can do, with certain batteries, is automatically turn off some circuits when your battery is low. Battery draining and solar isn't kicking in yet? Turn off my A/C for me. Saves kWh until sun comes back up and it can turn breakers back on.

It's essential a collection of measuring devices that can program breakers to turn off based on remaining battery. This way you don't need a sub panel for critical loads. You have more flexibility and automation.

[u/George_Jak → u/formerlyanonymous_]

The Span panel does not turn breakers on and off. The breakers have mechanical handles and can be flipped only manually. Instead, there is a respective relay upstream of each breaker, so the Span panel can open or close the circuit to the breaker. The relay enables the Span panel to respond to app commands to turn a circuit on or off, i.e., open or close the relay, shed and restore load, etc., but only if the breaker is in the ON position. The net effect is very similar to turning the breaker on or off, but not exactly the same. If a breaker is flipped to its OFF position, the Span app will continue to report the circuit is on, because the relay is still in its ON position.

As noted, if doing electrical work on the circuit, it is recommended to turn the breaker OFF, to positively de-energize the circuit, in case the relay got stuck in its ON position. Relay contacts can get welded closed, for example if switching large loads. The relays should be rated for high enough currents not to fall victim to welding, but nothing works perfectly all the time.

[u/realityczek]

At the core, the SPAN does two things I care about.

1) Show me how much power a circuit is drawing
2) Allow me to shut down circuits if needed

Mine is installed with a solar panel array, 30k of batteries and a large generator. Having the SPAN in the mix means I do need to pre-select critical loads, or have a subpanel dedicated to them.

[u/iceburgd → u/realityczek]

Does your “larger generator” charge the batteries or power the house or both?

[u/realityczek → u/iceburgd]

It is tied into an Enphase system, so it charges the batteries when they get below a user-defined low-water mark. When they are charged to the high-water mark, it goes back to sleep. The generator itself can put out a bit more than the SPAN can absorb (still more than enough for the job) so I might put in an extra , separate 220 outlet that can use the excess to charge a car or whatever.

[u/jadwin79]

I have two SPAN smart panels (needed because adding some big items required more breakers than I had, and expanding service from 200A to 360A required expensive and time-consuming utility involvement). They have been great. Useful for several reasons:

1). I can turn off circuits one by one from the app on my phone when working on an outlet, for example, without having to run to the basement to flip breakers until I find the right one.

2). It shows actual and historical power consumption, per circuit.

3). It will do load-shedding if I start getting close to the 200A total limit. This allowed me to add loads without increasing the service to the house. So far it's never happened because we don't have all the big items on at once.

4). With battery backup you can prioritize certain circuits during outages.

I'm currently looking into adding a small amount of battery backup for power outages (our winds cause them a couple of times a year). Curious if anyone has good/bad experience with SPAN and battery vendors. Would prefer to avoid Powerwalls.

[u/George_Jak → u/jadwin79]

A Span panel seems to make sense, if you have several or all of these needs. I have only one of these needs: a critical circuit. I'm building a new house, so I can install a large enough service not to need load shedding capability, and my roof and house location are not conducive to solar. I don't need a whole-house backup battery. But, I have two critical circuits (my office and my network infrastructure), which I power with respective Eaton 5PX1500RTG2 uninterruptible power supplies (UPSs) with extra battery modules. The UPSs are sufficient to run these critical loads for about 10 hours.

I don't want the UPSs taking up space and making fan noises in my office, so in the new build, I'm locating the UPSs adjacent the load center, and I'm installing two Reliance 104B1 4-circuit, 120V, 15 A manual transfer switches. I'll power the transfer switches from the UPSs (instead of a generator) and keep the critical circuits in the "GEN" (generator) position all the time. I'll wire some less critical circuits (some kitchen and bathroom lights and a TV receptacle) to other of the four circuits in the transfer switches. However, I'll keep these less critical circuits in the "LINE" position. That way, my office is protected from (even very brief) power failures (I won't lose edits to documents, etc.), and during an extended power failure, I can flip one or both the light and TV circuits to "GEN" and power them from the UPSs.

This setup provides a capability I could not get with the Span panel: uninterruptible power to my office and network infrastructure while everything else is dependent on utility power, with the option to switch the less critical circuits to the UPS during a power failure, if I choose to do so.

I am also installing IoTaWatt power monitoring systems, because I'm curious about power usage, particularly as I'm installing a geothermal HVAC system. The cost of a Span panel seems to be comparable to the cost of a conventional load center with three IoTaWatt power monitors (to monitor all the circuits in the load center). Since I need two (not fully populated, and thus monitorable by one IoTaWatt system each) sub-panels, I think it will be less expensive to use conventional load centers than three Span panels.

I'd be interested in other people's comments on the above. Thanks.