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
<ja...@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@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
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here: http://re-wrenches.org
List Address: RE-wrenches@lists.re-wrenches.org
Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
There are two list archives for searching. When one doesn't
work, try the other:
https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
http://www.re-wrenches.org/etiquette.htm
Check out or update participant bios:
http://www.members.re-wrenches.org
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here:http://re-wrenches.org
List Address:RE-wrenches@lists.re-wrenches.org
Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
There are two list archives for searching. When one doesn't work, try the other:
https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
http://www.re-wrenches.org/etiquette.htm
Check out or update participant bios:
http://www.members.re-wrenches.org
