[RE-wrenches] EG4 v HomeGrid battery systems update?
Christopher Warfel
cwarfel at entech-engineering.com
Wed Sep 3 12:03:41 PDT 2025
Hi Jason, I spoke with Solark re Homegrid and EG4. Did not mention you
name but your experience. You have been really helpful. I am centering
on open loop w EG4. My longest work commute is 15 minutes on this
island, so it's just having the time to trouble shoot. Plus, one mess
up, and everyone knows about it. Chris
On 9/3/2025 1:18 PM, Jason Szumlanski via RE-wrenches wrote:
> Nothing like a coincidence...
>
> A client on an island with three stacks of 8 HomeGrid batteries has
> just called me to report that the entire system is down. All of the
> battery BMS module displays are dark. I have mySolArk data from three
> inverters there that show the batteries were topped off and just
> idling along with solar covering the load at 5:00 pm last night when
> the power suddenly went out, killing the Starlink connection. I'm
> going for a boat ride tomorrow to check it out. Ugh.
>
> I will report my findings. Not sure if it's a battery or inverter
> issue, but the customer's handyman reported nothing on the battery
> screens, which seems strange to me. Even an error should not turn the
> display off, as far as I recall.
>
> P.S. No power loss notifications from Sol-Ark is a frustrating loss of
> functionality. I heard a rumor on Facebook that they are fixing this
> in mySolArk this month, but I'm not holding my breath.
>
>
> Jason Szumlanski
> Principal Solar Designer | Florida Solar Design Group
> NABCEP Certified Solar Professional (PVIP)
> Florida State Certified Solar Contractor CVC56956
> Florida Certified Electrical Contractor EC13013208
>
>
> On Tue, Sep 2, 2025 at 4:31 PM Jason Szumlanski
> <jason at floridasolardesigngroup.com> wrote:
>
> We have some stacks of HomeGrid out there in various capacities,
> from the smallest with five in a stack, up to four fully populated
> stacks of eight. In total, I oversee around 150 Stack'd batteries,
> including many that I installed and some that were installed by
> others. I will say that they are easy to install, have a nice bold
> visual interface, look good, and perform up to expectations. They
> communicate flawlessly with Sol-Ark 15k. However...
>
> I believe there is a fundamental design flaw in this stackable
> battery architecture. Here is why I am no longer offering HomeGrid
> in a nutshell:
>
> * When one battery in a stack has a fault, the entire stack
> faults out, which renders the stack non-functional until you
> either:
> 1. Remove the battery from the stack or turn the circuit
> breaker off, and:
> 2. Reconfigure all of the dip switches to remove the
> battery from the communication loop, then:
> 3. Reprogram the master BMS to recognize the new stack
> members and their positions.
> * If you have multiple stacks, you have to do all of the above,
> and in addition:
> 1. Remove a battery from each additional stack to balance
> them, then perform all of the above steps on each stack.
> 2. But before you reprogram each master BMS you have to take
> the stacks out of parallel communication, then reprogram
> the parallel stacks before operation again.
> 3. Making each stack equal is per HomeGrid support, but in
> practice, I don't know if it is necessary, especially if
> you are losing one of eight (12.5%). If you have smaller
> stacks, this might be a bigger issue.
> * To diagnose a battery issue with a laptop and cable and get
> warranty support, you can only do that with the master BMS
> because each battery does not have a comm port. That means you
> have to have the entire stack non-functional while you perform
> diagnostics, which is not ideal for off-grid settings,
> especially if there is only one stack.
> * If a battery fails to balance and becomes depleted, causing a
> fault, there are no simple terminal bolts to connect an
> external charger. I'm not sure how you would even accomplish a
> manual charge without opening up the case.
>
> The EG4 server rack batteries work in a fundamentally different
> way. Each battery has an independent BMS. When there is an alarm
> in a stack or stacks of batteries, the entire battery bank does
> not fault out. You can physically take a battery out of the stack
> without changing any dip switches on the other batteries. You can
> shut one down or experience a fault on one battery without any
> others shutting down. I have tried this with the LifePower4
> batteries, even when there are multiple communication strings of
> 16 batteries connected to a communication hub. The rest of the
> batteries just keep on working, which is the way it should be! The
> communication hub will just show zero values for the battery that
> is missing from the stack. I cannot confirm if this is the case
> with the LL batteries, but I suspect it would be. In a way, this
> is like having the batteries in an open loop in terms of
> resilience, with all of the benefits that closed-loop battery
> communications offers. I have had a small variety of battery
> issues with EG4, and not once has the whole bank of batteries been
> affected by one battery's issue.
>
> Side note about another server rack option: I can confirm that
> Pytes Ebox V1 batteries in a communication stack will shut down
> all batteries if one has a fault, at least confirmed by one
> situation I had. This is despite each battery having it's own BMS
> and console port to communicate with the batteries. The situation
> in my case was a battery that had no "Barcode" programmed into it,
> which was causing a parallel communication fault and shutting down
> the whole stack. In this case, physically bypassing the battery
> with the issue with a Cat5 coupling worked fine. There are no dip
> switches to set, and the master battery reconfigures the
> communication stack automatically. With Pytes' support, I was able
> to manually code in the Barcode to the BMS with a console cable,
> and the problem went away. I am not sure if all varieties of
> faults would have the same effect with Pytes EBoxes, but this
> communication issue definitely caused the whole stack to fault out.
>
>
> The phenomenon of the new breed of LFP batteries lacking
> reliability/redundancy inspired a blog post that I did just a
> couple of weeks ago:
> https://floridasolardesigngroup.com/homegrid-stackd-batteries-the-redundancy-fallacy
>
>
> A couple of other notes on HomeGrid:
>
> * They do not have any way to connect conduit to the BMS. You
> wouldn't want to anyway, especially with rigid conduit, since
> you might need to remove the BMS for service. The BMS should
> be at the bottom, in my opinion, for this reason. You can only
> run positive and negative battery cables out of the provided
> strain relief glands in free air, and it requires that the
> batteries be about 4 inches away from the wall. There is no
> suitable way to protect 100% of the battery cables.
> * Along the same lines, if you ever plan to expand the system,
> make sure you leave enough battery cable length to reach a
> higher level.
> * The lack of busbars is a really nice feature (until you get
> into larger systems).
> * The discharge rate supports the maximum input for a Sol-Ark
> 15K with, I believe, just three batteries.
> * I love their "busbar pair" designed specifically for the
> Sol-Ark 15K. I order a pair with every inverter, regardless of
> what battery I am using (although I am not actively selling
> Sol-Ark right now).
> * You can't monitor the condition of individual batteries with
> Solar Assistant, or any other tool remotely to my knowledge.
> You can't even monitor the condition of paralleled stacks.
> * The "app" for the batteries is mind-bendingly useless – unless
> I'm really missing something.
> * For some firmware and hardware versions, over-the-air updates
> are not possible, and HomeGrid will need to send you an update
> tool. To be fair, I think this is also the case with EG4 and
> some other manufacturers.
> * Once we received a shipment where three of eight batteries
> were in the right boxes, but there were no guts in the
> batteries at all! It was just an empty steel battery shell. We
> had to send them back to our supplier. The boxes actually said
> 13 Kg on the labels rather than 52 Kg, but nobody at the
> factory caught it. Strange.
> * HomeGrid Support is very competent, I would say among the best
> in terms of knowing their products inside and out, but it's
> 50/50 whether I get someone on the phone or get a call back in
> a timely manner that allows me to complete a service call.
> They are willing to schedule assistance if you have an
> off-grid situation that requires help.
>
>
> Is this a vote for EG4? Not necessarily, but it's hard to argue
> with the price and the superior reliability/redundancy aspects of
> the LifePower4/LL batteries. One battery fault should not shut
> down an entire system unless there is a legitimate safety hazard.
> It's possible that these are UL issues that require
> system shutdowns, but EG4 appears to have overcome the problems
> I've seen with other manufacturers' products.
>
> Like others mentioned, I prefer to go with the 14.3 kWh / 16 kWh
> sealed batteries. I feel they have better build quality (other
> than my recent rant about rust on the MNP PowerFlo16), and keeping
> components sealed up better just makes sense to me, especially in
> challenging environments. Of course, if you want more modularity
> in terms of expansion options and less impact if a single unit
> goes down, 5 kWh units might be a better option. There is no right
> or wrong option, I guess – sometimes it just comes down to
> priorities, space, mounting options, and price.
>
>
> Jason Szumlanski
> Principal Solar Designer | Florida Solar Design Group
> NABCEP Certified Solar Professional (PVIP)
> Florida State Certified Solar Contractor CVC56956
> Florida Certified Electrical Contractor EC13013208
>
>
> On Tue, Sep 2, 2025 at 10:41 AM Christopher Warfel via RE-wrenches
> <re-wrenches at lists.re-wrenches.org> wrote:
>
> Hi Wrenches, I went through the archives and read the
> comparison between
> these two. The HomeGrid manual was in such a mess (or my pdf
> reader was
> defunct), that I started looking at other options. If anyone
> has a
> strong opinion of either of these two, or something better, I
> would
> appreciate. We traditionally install small systems, and this
> would be
> one (@15kWh). I would prefer to use a racking system with the
> BMS as
> part of the packaging. Solark 12kPV multimode. Thank you, Chris
>
> --
> Christopher Warfel, PE
> ENTECH Engineering, Inc.
> PO Box 871, Block Island, RI 02807
> (401) 447-5773
>
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--
Christopher Warfel, PE
ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
(401) 447-5773
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