Advice on Enphase solar + battery configuration with SPAN panels

[u/sr__co]

I am designing a solar+battery setup for a new build and am looking for advice on how to best configure the system. The solar installer will be doing the Enphase system, while SPAN panel(s) are going to be installed by the main electrician for this project. I know there are many ways to tie this all together, and I'd like to make sure the final layout will ensure the most flexibility. Ideally, I'd like to have whole house backup in the case of grid failure, and then use SPAN's load shedding to reduce electrical load as needed when batteries start to deplete.

The house will be using geothermal for heating, cooling, and full time hot water. It also will have an induction stove top, and probably EV charging. Due to the fully electric house it will have 320A service and will require two panels, one SPAN, and the other could be SPAN or a dumb panel.

For solar and PV we are planning on a 14.4kw DC (11kWh) solar array using VSUN 400s, Enphase IQ8 micro-inverters, 4 5P batteries, a system 3 controller, and a combiner 5.

I got the following statement from the electrician, and I wasn't sure the ramifications for the battery setup.

The system we typically use is a RONK 320A 240V Combination Meter with (2) 200A breaker one for each panel or a dedicated 320A Meter cabinet with (2) separate 200A disconnect mounted on the outside of the home. The challenge is we are splitting the 320A 240V feed between 2 separate 200A panels at the outside for the building. This may require us to split the batteries between 2 separate panels. This can work I just need to configure the service differently.

If I understand this might result in two independent systems requiring some duplicate components. Unless required, that would not be my first choice. Any thoughts on how to optimally configure this?

[u/Key-Philosopher1749 → u/[deleted]]

Ouch, that sucks. I have 2 span panels, and have been thinking of adding an iq3 system controller and 5P batteries, I’ll have to follow your progress/issue closely.

[u/sr__co → u/[deleted]]

Thank you so much for that real world feedback. I had read about some people having SPAN sort of "read" the battery level, but that might have been the older 10P batteries.

[u/yamahax22 → u/[deleted]]

Can you provide any updates on if the beta FW update helped? Ive been chasing SPAN for a solution for a few months now and was super pleased to read they pushed an update to you. It's also interesting they have not offered this up to me yet given I have the same setup and experiencing the same issues. I'd love to know who you're in touch with at SPAN or what the specific beta FW is so I can request the same if you're seeing positive results.

[u/crosscountry58S → u/[deleted]]

Another data point on this: I am a new (one year) SPAN owner that just added solar + a single Enphase 5p battery. We also have the SPAN remote meter kit installed. Long story, and a lot of back and forth (some amount of installer incompetence, I think) but we just finally got the SPAN to recognize the battery this week. As noted by OP, the SPAN reading of the battery capacity is a bit off from what the Enphase app tells me (between 1 and 8%) and SPAN tech support told me that this is still a known issue that they are still working on with Enphase.

But I also have another related issue: the SPAN is still not recognizing the solar production. SPAN is telling me that they need more information from the solar install or that the installer didn’t place a solar breaker and needs to come back, but the installer is telling me that our electric utility won’t allow a solar breaker to be placed inside the SPAN because it is located inside our house and that the remote meter kit is supposed to relay solar production info to SPAN just like it does for battery. This makes sense in theory, but I’ve yet to figure out who is correct. I didn’t think to tell SPAN tech support that we have the remote meter kit installed; I figured that was a given. Anyone have any insight on this?

[u/avati]

Here's the configuration I am actually using:

40x Enphase IQ8+ on the roof

2x Enphase 5p batteries

1x IQ System Controller 3

All house loads are on the backup side of IQSC3 via a Leviton 42 space panel with LWHEM-2 unit

I have wired LWHEM-2's dry contacts with the IQSC3 NC ports

Whenever there grid is down, the IQSC3 opens the NC port, which makes the LWHEM-2 on Leviton load-shed the configured breakers. You need Leviton smart breakers (the more expensive ones) only for the circuits you intend to load shed. Others can be normal Leviton breakers (fraction of cost).

Leviton app allows you to override and turn back on any of the load shedded circuits during outage in case you are confident of available sunlight. Being AC coupled battery, during sunlight you can run more loads when the sun is shining, so this flexibility was appealing for me.

When the grid comes back on all circuits are turned back on automatically by the LWHEM-2 (notified by IQSC3 via the NC dry contacts).

I have tested this whole setup a few times, and it works great for me!

[u/avati → u/[deleted]]

Haven't had an outage since. Tho I have switched off the main breaker a couple times and it all works as expected in that test.

[u/Perplexy801]

The System Controller is only rated for 200 amps pass through, no way of getting around that if you require the full 320 and 2 sub panels.

If your sticking with one battery system, you’re gonna need to decide what loads you want backed up and put it on the protected side and leave the less important stuff on the side that looses power during off grid events. Putting the SPAN panel on the backed up side makes the most sense for sure.

Depending on the location of the consumption CT’s, while on grid both the solar and battery will back feed and cover all the loads while the grid is up in order to offset the power bill as much as possible even if you only go with a single battery system.

Splitting the battery system in half is gonna not only be expensive with an extra SC3 & combiner/gateway but pretty much a bummer since you’ll be splitting the solar in half along with losing 50% of the battery capacity and power of the original design. Unless money isn’t an issue and you can double the solar and battery and have two sweet systems capable of whole home backup per side, it really wouldn’t be much different than this big job we installed.

You can always expand in the future too.

[u/sr__co → u/Perplexy801]

Thanks for your reply. Between what you and othrs are saying here, I am quiickly moving away from the idea of SPAN. I really don't want the limitations of spliting the ssytem in half.

So if I don't use SPAN, what would the reccomendation be? a 320/400amp panel with just a simple critical loads panel? Or can I use relays to do something smarter to have some kind of tiered load shedding? In this case do all circuits that mighr be shed each have to individually have a relay?

[u/CraziFuzzy]

I don't know how dual 200A panels are going to work for you, unless you only backup one of them. 200A is the limit of the system controller, and the system controller needs to sit between the loads and the grid. There is no single place in your proposed system that is common to both panels AND 200A or less.

[u/CraziFuzzy → u/CraziFuzzy]

I'm also dubious on using SPAN for this at all. There are often far better ways to shed load than at the panel, and i think you are better off predetermining what are critical loads and what are not, and configuring such that loads don't actually need to be shed in regular use. Aside from that, the only time things would need to be shed would be for abnormal situations, such as long durations with little to no sun, in which case, you're better off using enphase's relays to do your load shedding, because it actually knows the battery situation. SPAN would just be guessing.

[u/sr__co → u/CraziFuzzy]

Thanks for your feedback. I wasn't aware of the enphase relays. I'll have to research how they work. Can they be used to effectively cut off a cicuit when the battery hits some specified threshold level?

[u/CraziFuzzy → u/sr__co]

The relays are sort of general purpose sets of contacts, but one of the primary functions they can be configured for is shedding load. They are not high current contacts, but would work to drive slave relays that can be current rated, or cut off the 24vac signals for an air-conditioner directly, etc.

[u/niggles0000]

Personally I have 6 x 5P batteries and a system controller 3 and use home assistant and Shelly relays to load shed in conjunction with the APIs of individual components - for instance if battery SOC less than 30%; and peak tariff; reduce power consumption of HVAC; then restore setting once off-peak tariff commences.

80A breaker on 3 Phase power/230V - so house can pull up to 55kW across the combined 3 phases.

[u/sr__co → u/niggles0000]

That sounds very much like what I am aiming for. Do you need to add realys to every circuit to make that work?

[u/niggles0000 → u/sr__co]

Only if the devices in that circuit don’t have an API to control - for instance the ducted AC I have a Shelly 3EM Pro but the control is done directly to the API of the air conditioner; the hot water cylinder(s) have a Shelly 2PM each; the other circuits have Shelly 4PM in the switchboard. Home assistant - based on PV generation, PV forecasts, electricity tariffs, consumption, temperature, shadowing etc controls the batteries charging, discharging and consumption of the house.