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
<[email protected]> 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 <[email protected]> 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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