[RE-wrenches] EG4 v HomeGrid battery systems update?
Jason Szumlanski
jason at floridasolardesigngroup.com
Wed Sep 3 12:19:16 PDT 2025
Happy to help.
Sol-Ark already knows I'm pretty ticked off with them. :)
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 Wed, Sep 3, 2025 at 3:05 PM Christopher Warfel via RE-wrenches
<re-wrenches at lists.re-wrenches.org> wrote:
> 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
> >
> >
> > [data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=3D]
> > On Tue, Sep 2, 2025 at 4:31 PM Jason Szumlanski <jason@
> > floridasolardesigngroup.com [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
> > > [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 [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
>
> _______________________________________________
> List sponsored by Redwood Alliance
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