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
>
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