If you’re looking for a safe, reliable way to build your own massive DIY off-grid solar system at a fraction of the cost, you’ve come to the right place. This is a detailed walk-through of the planning and installation of our 7,200W - 28kWH - 5,000W - 120V off-grid solar system that powers our entire homestead. By piecing together our own system from multiple components we were able to save thousands of dollars. Powered by SanTan Solar Panels, REPT LiFePO4 Batteries, REC BMS, @VictronEnergyBV Inverters, Charge Controllers & Color Control GX, and @IronRidgeSolar rack mounting.
CHAPTERS// 00:00 - Intro 00:51 - High Level Overview of System 01:19 - Article 01:54 - Wiring Diagram 02:20 - Solar Shed Recap 03:18 - Grid & Power Goals 05:40 - Solar Overview 07:14 - Planning & Building the Ground Mount 08:07 - IronRidge Design Assistant, Parts, & Panel Install 11:57 - Wiring Solar Panels 16:07 - Lithium Battery Bank 19:03 - Buying Lithium Cells from Alibaba 23:21 - Building the LiFePO4 Battery Back 27:05 - Fusing & Protecting the System 29:03 - Battery Management System (BMS) 31:01 - REC BMS 33:30 - REC BMS Wiring Guide 38:24 - Victron Color Control GX 42:02 - Victron Quattro Inverter Charger 43:45 - Grounding the System 44:50 - Victron MPPT Solar Charge Controllers 48:52 - Final Tweaks & Adjustments 50:28 - Real World Impressions & Usage 51:56 - What Would We Do Differently? 54:20 - Wrap Up 55:00 - Thanks
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[Music]
if you're looking for a safe and
reliable way to build your own massive
diy off-grid solar power system you've
come to the right place hey there i'm
ashley and this is jonathan we're a tiny
shiny home our family six has spent many
years traveling full time in our
renovated vintage airstream before
finding some off-grid property here in
cochise county arizona our dream here is
to build a sustainable off-grid desert
homestead using solar power water
catchment and natural building
techniques to create our own oasis in
the desert we'll be doing a full cost
breakdown in a separate article and
video but for now we'll be focusing on
the building the installation and the
wiring of our huge off-grid solar system
before we go any further let's give you
a high-level overview of our system 7
200 watts of solar panels 5 series 6 in
parallel
28 kilowatt hours of lithium batteries
two parallel 16 in series at 48 volts
5 000 watt inverter single phase at 120
volts surges to 10 000 watts this should
power our airstream our solar shed and
eventually our house if you get lost
during this video there is a full
nerdy detailed article
on our site with all this information
with links to buy everything with wiring
diagrams it's 10 000 words
it's ridiculous but it's full of good
information so make sure you go check
out this site below disclaimer i'm not
an electrician nor do i play one on
youtube all information here is solely
for entertainment purposes and all
electrical work should be performed by
qualified individuals according to local
electric codes cool
cool also yes you will hear roosters in
the background we live on a farm
[Music]
are you a visual person like me do you
just want to like see all this laid out
in excruciating detail without having to
watch 30 minutes or read 10 000 words
well you're in luck because i made a
wiring diagram of our entire setup you
can zoom in on it as close as you want
in high res glory you can buy it from
our site
right now before we get started we have
to mention that this solar power install
was part of a much larger project which
you can see right behind me this is our
earth bag solar shed office this was a
great way for us as a family to build
naturally and sustainably and try out a
ton of natural building techniques it
was so much work but it turned out so
good it doubles as an office and a guest
room but it also has all that power gear
inside setting up an independent
off-grid solar system was a huge part of
our infrastructure out here on our
homestead we're excited to share this
power setup with you because we think we
found a great way to create a large
it's okay just keep going gosh we're
excited to share this power setup with
you because we think we found an
incredibly cost effective way to make a
massive safe reliable off-grid solar
power system
[Music]
[Music]
now that could we have
built oh i'm not going to talk to you
sorry
all right
now could we have just hooked up to the
grid sure it's about a half mile away to
the nearest pole we could have done that
for about 35 000
that's crazy but do we want to do that
no we want to be off-grid and
sustainable that's kind of the whole
point of why we moved out here but it
turns out that we were able to build our
own system for way less than that oh
yeah so it totally worked out anyway now
we do have to talk about our power goals
because that's going to be different for
everybody right right we came from a
background of traveling full-time in our
airstream and most of that time we were
off grid and boondocking so we're
already pretty used to being like low
power low energy and not not low energy
but like
we're not using a lot of energy right
yeah from a high level overview we knew
we wanted to go with a 48 volt battery
system because the conversion from 48 to
120 volts is much better than a 12 or 24
volt
we also knew that we didn't need 220 now
that might be controversial but we have
been used to living
off-grid low power for such a long time
we decided to stay at 120. we decided we
didn't need a dryer now
okay some of you are going to say why
does she not want a dryer um we live in
arizona most of the year it's sunny and
if for some reason i can't dry things
outside i'll just run to the laundromat
and dry it real fast but the plan is to
just hang all of our laundry out on the
line yeah low humidity helps a lot
for cooking and heating we do have a
mini split that uses very little power
for heating but otherwise we're going to
supplement with like gas propane wood
there's much more efficient ways to heat
than to just run electricity to
everything also we're building all of
our buildings with hybrid adobe
earthbags which means we are creating
thermal mass and taking advantage of
passive solar and should we ever decide
to change our minds and say well maybe
we do actually need 220 volts or we've
wired and sized the system to grow with
us as needed so that means i might get a
dryer maybe one day okay all right
enough of this overview stuff let's get
to it first thing
solar ground
[Music]
first question i know you're going to
ask is
why did you build this huge solar panel
array and why didn't you just put your
solar panels on the roof of your solar
shed it's a good question the reason for
that is that we built this to take
advantage of passive solar that means
that there's clear story windows facing
south that let the sun come in in the
winter but then there's an overhang so
that in the summer those windows are
shaded and the roof is slanted
north so that means we can't put solar
panels on that roof because it's totally
facing the wrong way you need to be
facing south in our case preferably at
about 30 degrees so we had to build a
solar ground now our first step to
saving money on this install was solar
panels so here's the thing solar panels
get installed in residential and
commercial installations but then often
they're replaced every couple of years
due to contracts they still work totally
fine but thankfully there's a company
called santan solar they buy these used
panels they re-certify them and then
they sell them back to you at a fraction
of the cost so we took advantage of
their yearly sidewalk sale and bought 30
of these 240 watt residential panels for
only 25 apiece that means we got 7 200
watts of solar for less than 800
that's crazy now it turns out that was
actually the smallest expense in related
to our solar panels because we still had
to build a ground mount and that is what
we're going to talk about
[Music]
next this solar ground mount ended up
being a massive project in and of itself
there was so much research to do and so
many things to plan for
the first was that we needed to make
sure that these panels were going to be
as efficient as possible so there's a
couple of online calculators you can use
to tell you how to tilt them and then
which way to point them in our case it
was 30 degrees and then 10 degrees east
of south we live in the high desert of
southeast arizona which means that we
get insane monsoons and weather events
and even a little bit of snow so we had
to engineer this thing to withstand 100
mile an hour plus winds in very sandy
soil conditions that means we look to
the experts to help us figure this out
because this is way too much to figure
out on your own thankfully there's a
company called ironridge and they make a
lot of the components that allow you to
attach the solar panels to your frame
they also have an online assistant tool
that will do so much of this work for
you they'll help you figure out exactly
how much pipe you need how much cement
you need how to cut everything what your
angle should be they provide full
drawings that can even help you get
permitted if that's something that you
have to worry about for your local codes
so let's start with the iron ridge
components that you're going to need top
caps
rails
rail connectors ufo or universal fit
object module and stopper sleeves
end caps and wire clips
and a grounding
while we were able to directly order
those items from ironridge we had to
source other items like the three inch
schedule 40 pipe
a ton of cinder blocks a bunch of cement
all ourselves using the diagrams
provided by ironridge we picked this
spot for our solar array because it's
about 100 feet to the solar shed and we
didn't want to run
any heavier gauge wire longer than we
had to we started by augering the eight
holes that were five and a half feet
deep by two feet wide then we had to cut
our steel pipe because the pipeline came
in 20 foot segments and our entire array
is over 32 feet we had to do all that
math and figure out how to cut the legs
to go down in the holes and then also
how to split the long ones so that they
landed right on top of a pier and we're
connected by a top cap it's kind of
confusing
here's a picture
[Music]
and again i have to give a shout out to
the iron ridge design assistant tool
because it helped us know exactly how
long to cut all these pieces of pipe
once the holes were dug it was time to
use the stacks of cinder blocks and
jacks to get the horizontal rails in
place both parallel with each other and
leveled horizontally
as you can imagine lining all this up
took a while and we had to readjust many
times once these were in place it was
just a matter of attaching the vertical
piers via iron ridge's top caps letting
them hang in the holes and then filling
with cement not that this was easy we're
talking like 200 plus bags of cement by
the time we got finished none of us ever
wanted to see a bag of cement again with
the frame in place it was time to add
the rails which are the heart of the
iron ridge system we went with the
xr1000 because they're rated for higher
wind and heavier snow loads and all that
stuff and because of the way we were
setting up our solar panels we needed 12
rails total one on each side of the
array so here's a close-up of how these
components work this is the top cap so
your pipe is going to slide up inside
there and then you tighten it up to hold
it in place then it uses the u-bolt to
go over and attach to this one and then
you tighten it up the rails are then
connected to the pipe via a rail
connector which is sort of a an l
bracket that uses the u-bolt and then
slides into the track and then it can
slide up and down and move exactly where
it needs to and then you can tighten it
into place one thing we realized using
this system is how forgiving it is we
were like super worried about making
sure everything was like perfectly lined
up but it turns out that because
everything can move every which way it's
a lot more forgiving than we thought it
was and it made it much easier to
install the next step is that you're
going to use what are called ufos or
universal fit objects
these go into the rail there's a little
track on top of the rail that will slide
into
and then the panel will set down
on that and then you tighten it up and
it clamps it down to start your panel
array you have to use a stopper sleeve
on the ufo to give it a flat surface to
set against then it's just a matter of
setting new panels in with ufos in each
track all the way up one final thing
about the iron ridge system is that
everything should be torqued to exact
specs so make sure you have both a foot
pound and an inch pound torque wrench
with the ground mount built and the
panels attached it was time to turn our
attention to wiring we already decided
that we wanted to run these five in
series so we could jack the voltage up
keep the amps low and then keep our wire
runs a smaller gauge going from the
array into the solar shed also by
creating high voltage arrays we were
able to pull in more power earlier in
the day later in the day and when it's
cloudy here's how the math worked out
each 240 watt solar panel array
connected five in series produced 1200
watts 186 volts and eight amps then
connecting all six arrays in parallel
created a 7200 watt 186 volt 50 amp
solar panel system from a physical
connection standpoint connecting in
series means that you take the positive
from one panel and connect it to the
negative of the next panel and then you
do that all the way down
but then you have one at the end that
you're going to have to run back into
your combiner box so we had to do a
bunch of math and a bunch of measuring
and then buy a bunch of pv wire and mc4
connectors and extend and create our own
wires to make this all work in order to
get all of our wires into our combiner
box we had to buy 300 feet of solar wire
and 24 mc4 connectors with each series
of five panels we needed to connect and
parallel and so that's what this
combiner box does you can see this one
has four inputs so we have four of our
five panel arrays on this one and then
two on the other one and also that means
that we have room to expand on that
other box if we ever want to add more
panels the other important thing we
needed as part of this install was a
lightning arrester we hadn't heard of
this until we moved out into the wide
open spaces of the desert but apparently
indirect lightning strikes are a thing
out here and so just in case
this ground mount were to ever get hit
by lightning it would run through this
lightning arrestor it would run to the
copper ground rods that we have
installed it would trip and none of that
surge would ever go into the solar shed
where all of our gear is the other cool
thing about this box is that it's
already pre-wired for you so all you
have to do is make up your mc4
connections connect them into the bottom
and then run your pv wire up and connect
it here and all this is already taken
care of honestly i think the hardest
part of all this was figuring out how to
mount these boxes
to the steel pipe we used some unistrut
and a bunch of plywood and it's super
janky but hey it's on there and it works
[Music]
next up is trenching now obviously
everyone's trenching situation is going
to be very different like we mentioned
we had to run a little over a hundred
feet from this array to the solar shed
so what we did is we took the positive
and negative wire coming out of each of
these we ran it up through a service
entrance goes down into the ground all
the way over and then through some lb
connections on the outside of the solar
shift because of the length of the run
and the amperage we use six gauge wire
which will actually allow us to increase
our panels if we ever need to but this
ran through one and a half inch conduit
through multiple twists and turns and we
dug it all by hand and it was ridiculous
but we got it done now one last cool
thing about this iron ridge system is
grounding grounding is very important
you're putting a ton of power through
the system so
the neat thing is that the way the iron
ridge ground mount is designed is that
all the metal is all touching each other
so the system is grounded by itself but
they also give you a grounding lug
connection that connects to the frame
and you run a bare copper wire to an
eight foot ground rod we also wanted to
make sure that with our lightning
arresters they also need to run to a
ground rod so what we did is we put two
ground rods in but one here
for the iron ridge actual array and then
we put one in here that the lightning
arrestors connect to and then we
connected it all together just in case
because hey
lining sucks
[Music]
another big part of how we saved money
during the solar install was batteries
now there are so many different ways to
build a large battery bank now but i
think we've reached the point where
lithium batteries are definitely the
best choice for a large bank that you
want to last for a long time lead acid
or agm batteries are going to be bigger
and heavier you're only going to get
half the capacity they're going to have
voltage sag when they get hydras on them
but lithiums will be smaller and lighter
they don't have to be vented they don't
have any voltage sag and you can charge
them quickly
they're just much much better overall
and with lithium batteries running at
2000 to 3000 cycles they could totally
last 15 to 20 years which is crazy the
one downside to lithium is that they
need a brain or a bms to help manage
voltage and temperature and balancing
but overall if you're going to invest
this much money into a large battery
bank that's going to run your entire
property the bms is totally worth the
investment so these are the main options
for lithium batteries on the market
right now tesla sells its power wall
which is a battery pack inverter and
charger all in one you can get used
electric car batteries like the chevy
volt and nissan leaf rack mounted 48
volt systems like the life power eg4 and
of course everyone's getting into the
lithium cell game with companies like
battleborn that have a bms built into
each battery there are some issues with
each of these though power walls are
crazy expensive about five hundred
dollars per kilowatt hour battleborns
are also ridiculously expensive at about
720 dollars per kilowatt hour and the
built-in bms doesn't interface well if
you have more than one the rack mounted
systems are a little bit cheaper around
three hundred dollars per kilowatt hour
and electric car battery prices are all
over the place from 170 to 300 per
kilowatt hour but they're difficult to
source and they come in hard to open
housings with lots of voltage and setup
quirks what if you could buy small
efficient easy to connect cells to build
your own battery bank at a fraction of
the cost enter alibaba so here's the
thing other than tesla every single one
of those battery cells i mentioned
they're all made in china
so maybe you should just buy your
batteries directly from china anyway
recently there's been a surge in
competition for these types of cells if
you go to alibaba and you type in 280
amp hour lithium battery pack you will
get thousands of results in fact we only
spent 130 dollars per kilowatt hour for
our 28 kilowatt hour battery bank it was
about 3 800
and that was in the middle of covid when
the prices went crazy high so they could
even be lower now the tesla or
battleborn options would have cost us
five to seven times for the amount of
storage
you just have to assemble the packs
yourself and we'll get to that in a
minute now before i get too excited
about alibaba and saving tons of money
on lithium batteries
i have to tell you a story so settle in
we're going to recount the saga of
buying batteries from alibaba and having
them shipped directly from china our
story begins with a search
[Music]
like i said searching for a 280 amp hour
grade a lithium cell on alibaba gets you
a lot of results so i reached out to a
few suppliers to get estimates things
started out well the representatives
were asking important questions like
what voltage battery bank are you
building
are you buying the right amount how are
you going to use it what's the
application they all got me estimates
and we picked one that seemed like a
pretty good price and then that's when
things started to get weird i tried to
pay for the order with a credit card and
it was declined not by my credit card
company but by alibaba and then because
alibaba had deemed my credit card
dangerous i couldn't pay with any credit
cards for anything so i was left with
like paypal and western union as a way
to pay which felt super sketchy didn't
want to do western union so i ended up
doing paypal and it went through okay
finally first hurdle we're past it then
like two days later i get an email from
the supplier and they're like hey
those sales you ordered we actually
don't have them in stock even though
they told me that they did
we would like to give you a different
battery that's more capacity for the
same price because we're going to keep
our word but here's the thing it wasn't
the same cell so
if you've looked into buying these
batteries online you may have run across
a few acronyms there's eve
rept
and a few other ones but the the main
thing is that evee cells have been
around a lot longer and there's just a
lot more sort of anecdotal data out
there that we can use to see that they
do last a long time and they are what
they say they are
however they were out of the eve cells
and they wanted to send me rept which is
kind of like a newer kid on the block
and there's not that much information
about them
so i was like i'd really like the ones i
paid for and they said well it's going
to be six months before we get some in
we were in the middle of covid all the
shipping ports were backing up we really
needed to get these batteries here in
stock so i went ahead with the rept
and just kind of dealt with it and i
figured well you know they're so cheap
if they really don't work out then we'll
just get something else and one thing i
should mention is that you have to
really plan ahead for these because it
does take a couple of months for these
to actually make it from china
going over the sea and then come to you
there were definitely a few points
during this process where i started to
worry if i got scammed because when they
shipped them they gave me a bunch of
fedex tracking numbers that never really
updated they just said pending the
entire time and i would ask them for
some sort of update on shipping and they
would send me shipping manifest
completely in chinese it didn't really
help me and then they're like well it's
in port but the ports are backed up and
then they're like well now it's in
customs and it could be like a week or a
month
and
we waited and we waited and we waited
and then all of a sudden two and a half
months later fedex showed up with eight
huge boxes
and that fedex tracking number still
never updated it still says pending to
this day so i'll have to say if you're
willing to wait a little bit longer and
do your research you can get a large
lithium battery bank for a fraction of
the cost also several other youtubers
have had issues trying to buy battery
cells like this and instead of getting
grade a cells they end up with grade b
which have some problems with swelling
or maybe they don't have the full
capacity ratings
but i've got a few tips here to help you
avoid that try going through alibaba
instead of aliexpress
stick to well-known cell names like eve
or rept
get quotes from multiple suppliers and
avoid any prices that seem too good to
be true if you're curious we bought
ourselves from this company
and this is the exact listing the good
news is our batteries were all packaged
very securely no swelling perfectly top
balanced and we can't say a bad thing
about now let's head inside and look at
exactly how we built this battery bank
[Music]
while using these small compact cells
made it easier to build their own
battery bank that's not to say it wasn't
difficult building something safe and
secure for a battery bank this big is
still hard to do first we had to decide
how we were going to connect them
together batteries connected in series
means that their voltages are added
together the batteries wired in parallel
means their amp hours are added together
we knew that we needed a 48 volt system
we also knew that our bms was going to
have 16 inputs so really it was just a
matter of doing a bunch of math we could
have bought 16 of the 3.2 volt battery
cells connected them all in series and
created a 48 volt system because 3.2
volts times 16 equals 51.2 volts but
that only would have been about 14
kilowatt hours of storage the way you
figure that out is you take the amp hour
of each cell and multiply it times the
volts so 280 amp hours times about 50
volts gives you 14 kilowatt hours that's
a decent amount of storage but because
we're building this for our entire
homestead we knew we needed more
simplest way to get more was just to
double the amount of batteries so we
bought 32 batteries grouped them
together in packs of two via parallel
connection and then connected each pack
of two
in series to create a 28 kilowatt hour
battery bank instead the battery shipped
with some really flimsy bus bars and
nuts and washers but we opted to go get
our own copper bar stock and basically
redo those connections to get our
maximum flow through before we could
connect anything though we had to build
a battery box to keep all these
batteries in we had to decide which way
to configure them because really they're
best connected end-to-end in a series
configuration but we didn't have that
much room in this little power corner of
our solar shed so we basically took
16 and then another 16 and stack them on
top of each other lithium batteries need
to be compressed so that they don't
swell over time so what we did is we
took some thick plywood some long pieces
of all thread rod some heavy duty
nuts and washers and we basically put
two pieces of wood on each
end of the 16 group and then use the all
thread to compress it together and hold
it so that they wouldn't expand and
contract during usage then we welded a
metal frame
to hold each group of 16 batteries each
cell weighs about 11 and a half pounds
so a 4016 weighed almost 200 pounds huge
shout out and thanks to juwan and
michelle from beginning from this
morning they not only helped us plan
this whole system but they also brought
their welding gear and helped us build
this battery box with our packs created
we slid them into place and began to
cut and drill holes in the copper bus
bars so that we could connect everything
together remember we were connecting two
cells in parallel and then each pack of
two is connected in series this is a
little confusing so here's a graphic of
what it looks like
then all we needed to do was continue
that series connection from the top row
to the bottom row and we did that with a
large two ot copper welding wire now
before we tightened the nuts down to
hold the bus bars in place we did have
to run our bms wires and we'll get into
the bms install in a minute but just
know that we ran a bunch of 18 gauge
wires to each pack of two so that the
bms can balance and keep track of the
voltage in each cell and finally we
needed to run heavy duty two out wire
from the positive post and the negative
post of the battery into the system and
we'll cover that more
[Music]
before we get into wiring the bms i want
to talk about fusing and protecting the
system with something this big with this
much power flowing through it you want
multiple points of protection so i'm
just going to show you real quick what
we've added kind of talk about each one
and show you sort of how the power flows
through
so right off of the positive
battery post we're going to run through
a 300 amp t-class fuse this will protect
the system and the batteries it'll
protect both ways if there were some
sort of power surge
there's also a battery disconnect and so
this is a switch that will cut off any
power from the batteries
if you need to do any maintenance or
anything like that after the switch
you're going to run through your
contactor so everything on this side of
the contactor
is always going to have power unless
this blows or you turn this off but
everything on this side of the contactor
will only have power if the bms says
it's okay for it to and so it's checking
for voltage and temperature and all
sorts of things the last major part of
the 120 volt side is that you're gonna
have power coming from that contactor
into your inverter but first it's going
to flow through
a circuit breaker this is a 200 amp
circuit breaker
again we can flip this off if we want to
shut power off to the inverter but it
also protects the system if the inverter
decides to go haywire and so that way
power doesn't flow back to the system if
we don't want it to and then finally
from the negative post on the battery
you're going to run through your current
sensing shunt
which is also connected to the inverter
and it looks for state of charge one
important note when you're installing
any of these circuit breakers or
switches or fuses they should all either
be removed or turned off while you're
installing until you're ready to boot
the system
[Music]
i can't overstate how important a bms or
battery management system is to a large
battery bank like this you have to
protect these cells from overcharging
under charging from temperature extremes
you have to make sure that they're
balanced properly or that 15 to 20 year
reference that i gave you earlier isn't
gonna hold up because they're gonna die
way too early here's everything that a
good bms should do over voltage
overcharging the batteries can be very
dangerous and cause swelling or fires
the bms constantly checks for high
voltage and shuts off the system if
needed under voltage
batteries that have discharged too low
can also be permanently damaged if tried
to use during that state the bms checks
for low voltage and will shut off the
system until it reaches a safe threshold
high temperatures the stability of
lithium battery cells depends on keeping
them within their operating temperatures
if you're charging them while they're
too hot this could lead to a fire low
temperatures lithium batteries will be
damaged if you try to charge them and
their internal temperature is below 32
degrees so the bms checks for cell
temperature and shuts down the charging
aspect if needed charge flow and
hysteresis a good bms will let you set
these parameters so that over voltage
and temperature issues never happen in
the first place the bms should talk to
your charge controller and help fill and
float the system safely keeping all your
cells near the same voltages will
drastically increase their life a good
bms should be able to equalize or
balance all the cells voltages by
diverting some current from higher
voltage cells to the whole pack or the
whole pack to a lower voltage cell
trying to run a large off-grid battery
bank without a bms is asking for all
sorts of problems you're going to reduce
the life of the battery reduce your turn
on investment and possibly start a fire
so spend the extra cash and get a good
bms for your batteries what bms should
you get it's a great question we chose
rec bms for these reasons they have a
great reputation for stability and
customization
and are very knowledgeable of using
batteries off-grid the support is
fantastic and very technically detailed
their products can talk natively to
victron gear using the proprietary
victron ve can protocol this was
important for setting both charge
controllers and the color control gx
which is the heart of our monitoring
system deep level settings are
accessible via their new wi-fi module so
you don't have to connect a computer to
make updates it measures battery
temperatures via probes but also has an
internal temperature for the unit itself
displays real time info at the cell
level on its own touch screen can be
configured with a pre-charge delay which
should prolong the life of your
equipment by sending a trickle charge to
components so that they don't get hit
with a large inrush of current and
measures using a precision shunt
resistor this gives a very accurate
state of charge percentage you may be
wondering why we didn't offer a built-in
bms we mentioned earlier some batteries
come with built-in bms's but here's the
problem with that not only does it
inflate the cost but it means that many
of the sensors and the elements are all
proprietary and they're all enclosed
where you can't really get to them so in
our case if a temperature sensor ever
goes bad if a voltage wire ever goes bad
those are easy to replace we can do it
ourselves and that's much better for
long-term maintenance this is our
recommended shopping list for rec bms
components the rec q bms 16s which is
the main unit
current sensing shunt
temperature sensors
pre-charge resistor delay
wi-fi module
lcd touch
display your cable for victron v you can
your contactor
and your current sensor harness now in
our article we have affiliate links to
all the rec components but i did want to
give you a heads up if you go to the
link for the actual bms unit there you
can actually add almost all of these
other elements as part of a package and
you save like five percent for each
thing so make sure you do it that way if
you're going to build your own system as
much as we love our rec bms it was by
far the most complicated part of the
install so i'm going to walk you through
every single wire every single
connection and show you how it all works
together
[Music]
now we're going to walk through in order
step by step each thing that we're going
to connect to the bms this is very
technical so i'm not going to be on
screen a lot here but we are going to
show up close
video of each connection and also refer
to our wiring diagram step one turn off
the bms and pull the cell wiring harness
out and start running individual wires
from each battery cell to the
corresponding number we use small 18
gauge wire one end will go into the
screw terminal and the other we crimped
on a ring terminal to go in the positive
post of the cell keep in mind that the
first input on the harness actually goes
to your negative connection on the
battery
then you connect to all the positives in
order down the line and do not plug this
wiring harness in until later
remember how we grouped our batteries in
packs of two this was so we would have
16 cells which happens to be the exact
number of inputs that the rec q bms has
wiring up 16 cells will take some time
but this is an important step in letting
the bms know exactly what the cell
voltage is of each battery cell as well
as enabling that important balancing
feature that we'll need to maintain the
batteries step two now it's time to
connect your ve can bus cable from the
bms to the victron color control gx this
allows the bms to talk natively to the
central hub of your power system the
next one gets a little complicated it
can go directly to your lcd touch
display this touch screen gives you all
sorts of useful info like your state of
charge cell temperatures and voltage or
you can connect it through the rec wi-fi
module now we highly recommend getting
the wi-fi module for these reasons
number one if you don't have it you have
to buy some pc software use a special
cable go through a windows driver
installation setup and because it uses
your rs-485 port that means anytime you
want to use it you have to disconnect
your display here we only use mac so
having to buy a pc to do this would just
be a huge pain in the butt the wi-fi
module stays connected all the time and
is easily accessible from any device via
a wi-fi connection
you can still get access to the full
programming features of the bms but in a
much simpler and easier to use web
version of the application you can also
choose to connect it to your existing
wi-fi network so that any device can
quickly connect at any time without
needing to connect directly to the wi-fi
unit you'll likely be doing a lot of
tweaking to the settings in the
beginning as well as monitoring so being
able to do this on any device is
incredibly convenient by the time you
buy the pc software and cable you're
halfway to the cost of the wi-fi module
anyway so it's totally worth the extra
upgrade so yes we recommend getting the
wi-fi module that means that the rs-485
port on the bms goes to the wi-fi
module's main communication port note
that there are small positive and
negative wires coming out of this cable
that need to be connected to your main
positive and negative post step four use
the wi-fi module's display cable to
connect to the rec bms display this also
has negative and positive wires that
need to connect to your main positive
and negative post step five is
temperature sensors this cable comes
with three sensors attached just screw
into the bms and then place the sensors
where you like on your batteries with
some tape step six the current sensor
wire will connect directly to the
positive and negative input screws on
the top of your shot
this provides an accurate system state
of charge back to the bms
remember that the positive side of the
shunt is where your battery negative
connects and the negative side of the
shunt is for everything else moving on
we have the output wiring harness again
make all connections with this unplugged
you'll plug everything back in later in
a certain order step seven now we
mentioned the pre-charge unit above if
you're wondering exactly what this does
i'm just going to read it to you it
charges the input capacitors of the
system components before the main
contactor switches on which eliminates
high inrush currents at the switch-on of
the contactor and prolongs the contactor
lifespan dramatically for the bms wiring
harness you only have two connections
one that goes straight to the battery
side of your contactor and one that goes
to the bms input positive on the
pre-charged unit the rest of the
pre-charged connections are pretty
self-explanatory
system plus goes to the system side of
your contactor battery plus goes to the
battery side of your contactor
system negative goes to the negative
side of your shunt
contactor positive goes to the positive
contactor wire
contactor negative goes to the negative
contactor wire
yeah like i said it's a lot of
wires
but hey now you know how to hook it up
so let's look at the victron color
control gx
[Music]
the victron color control gx is the
heart of your monitoring system it's
going to give live info at a glance
everything is going to connect to it and
with the vrm or victron remote
management portal you can access your
power system from anywhere in the world
at any time wow that's cool thanks bab
before you fire up your system for the
first time you're going to want to make
sure everything's connected to it so
let's look at all the wires you've
already connected the rec bms via the ve
can bus but in order for it to talk
directly to everything you've got a few
more cables to run
to connect your inverter use a ve bus or
ethernet cable and for the mppt solar
charge controllers use ve direct cables
the display also needs power so connect
its positive and negative wires to the
positive and negative of the system you
may need to put a terminator plug into
the second ve can slot it does come with
one and if you want to run the vrm
portal full time a usb wi-fi adapter
will allow you to connect the display to
your network at this point you've built
out the base of your system now we're
going to look at solar charge
controllers and the inverter in a minute
but for now let's look at the process
for booting it up for the first time
number one
plug in the outputs wire harness on the
bms
number two
plug in the cell wire harness on the bms
number three turn on your battery
disconnect switch
number four
turn on the bms you'll see a red light
at this point the bms is going to run a
bunch of checks after seven seconds if
all is well you will hear a clunk of
your contactor and the light will turn
green and that means the bms says
everything's good now the bms is going
to need to have all the proper settings
for your specific battery type this will
pass along crucial information like load
and state of charge to the color control
gx if you want to see the settings that
we use for our specific batteries make
sure you go and check out the article
i've got everything in there but of
course always send your specific
schematics to rec and ask them to help
you set up your settings exactly we
still need to adjust some settings for
the victron color control gx so that the
victron unit can read from the bms i'm
not going to go through all those here
just make sure you go to our article
we've got them all listed out if you've
connected everything properly you should
see the same state of charge numbers on
the rec bms display and the victron
color control gx display because now
they're talking to each other keep in
mind that most systems are going to
treat a battery pack as 50
by default until it has been charged to
a full 100 so if you aren't seeing the
numbers you expect there just give it
some time until it's been fully charged
if you haven't already make sure that
you have power running into your
inverter this is very simple you're just
going to run a big 2 oh welding cable
from the system side of your contactor
into the positive in and then from the
negative side of your shunt to the
negative end and of course i should
mention that our two ot wiring is based
on our system size how many amps and
watts we're pushing through you may need
to go bigger or smaller depending on
your setup with the power run to your
inverter it's time to flip on that 200
amp pull toggle and then turn on the
inverter and see if your victron color
control gx changes to status of
inverting and see if the invert is
actually working
[Music]
congrats you've got power but we're not
finished yet so what we're gonna do is
shut everything back down and then
continue making our other connections
number one turn off your inverter number
two flip your 200 amp pull toggle
number three turn off the bms
number four switch the battery
disconnect off
at this point you've already got your
positive and negative trunk wires
providing power to the inverter and
you've got your victron cable going from
the inverter to the color control gx but
there are still more connections we need
to make if you want to charge your
batteries via generator you can run some
wire to the ac in one connection then
connect the other side of the wire to a
30 amp plug note that we're now in three
wire territory black is line white is
neutral and green is ground
also know that you'll need to adjust the
charging settings of the inverter based
on your generator size we have a small 3
500 watt harbor freight generator but
victron is assuming we'll be using
something much larger as a backup the
default input current limit is upwards
of 60 amps but our generator only puts
out about 25. you're gonna have to
change the setting for smaller
generators but victron does not make
this easy we had to do the dip switch
dance a very convoluted way to set your
input current via tiny switches behind
the top panel of the quattro
i won't get into this here you'll have
to read the manual carefully but once
it's changed you'll see the number for
input current limit updated by going to
menu quattro inverter on the color
control gx supposedly you can get in and
change this with a special cable and
some software on your computer as well
but we haven't tried that yet the
quattro requires all grounding cables to
be connected together so not only will
the ac out need its ground connected to
the ground post the ac in but also
grounding chassis from your solar charge
controllers and from the inverter itself
which is kind of weird that all connects
to a single post and then that post runs
a bare six gauge copper wire out to
another eight foot ground rod on the
outside of the building and finally we
get to the whole point of this setup
clean stable 120 volt power this is as
simple as running a romex cable from the
ac out into a circuit breaker box or
however it is that you need to connect
your setup in our case we ran to a main
lug panel which separates the power into
three connections one for our house one
for this solar shed and one for our
airstream and then we have another
breaker box for all the elements inside
the solar shed but hey everyone is going
to run their 120 volt or 220 volt
differently so we're not going to get
into any more detail
[Music]
let's talk solar charge controllers now
technically you can set this up at any
point during the process we just happen
to be waiting on
trenching and then also a few of these
elements to ship from amazon so we
hooked these up last so even though we
have the combiner boxes back at the
solar panel array with their own circuit
breakers we've added a second set of
circuit breakers right here coming in
these are from the positive lines on
each combiner box array from there we
ran two gauge cable
from the circuit breaker into the
positive pv
of each one
and then also the negative lines still
came through and they just go directly
to the negative pv
then out of that we're going to go
through another set of circuit breakers
right here these are 100 amps each and
so the positive power
from the solar charge controllers is
going to run through here and then down
to that system side of the contactor
then you're also going to run two gauge
wire from the negative side of both
solar charge controllers all the way
down to your shot just for reference
these are
40 amp circuit breakers and these are
100 amp circuit breakers these provide a
second layer of protection just in case
whatever happens out there those circuit
breakers maybe they didn't catch it and
the power still came through these
should trip if it's over 40 amps and it
shouldn't ruin these solar charge
controllers
also because we have so much solar it
means that during the day many of our
appliances are running directly off of
solar power anyway so if we ever need to
work on the system just because we've
we've flipped the battery switch
disconnect doesn't mean that there's no
power in the system so we have to make
sure we flip off the circuit breakers
here as well make sure there's no power
flowing through and we don't electrocute
ourselves now remember we had two
combiner boxes outside and so we decided
to go
with two charge controllers we've
oversized these on purpose again for
feature expandability these are 250 volt
85 amp charge controllers so they're
plenty big and we can always add more
solar if we need to without having to
replace them don't forget like we
mentioned earlier chassis ground
connections they're kind of over here on
the side they're hard to see but they
run from both units to the grounding lug
on the inverter once all of your panels
are connected and all your wires are run
inside it's time to boot up the system
with your solar power for the first time
here's the order number one turn on the
battery disconnect switch number two
turn on the bms and wait for the
contactor to turn on number three flip
on the breakers in the combiner boxes at
the solar panel ground mount number four
turn on the 100 amp pull toggle switches
going from the mppt charge controllers
to the system
number five turn on the 40 amp circuit
breakers going from the solar panel
array to the mppt charge controllers i
should note that i actually did this
backwards the first time and caused a
bunch of headaches for myself in my
attempt to be extra careful i actually
left all of my circuit breakers off when
turning this stuff on for the first time
these are smart solar charge controllers
and when they boot up for the first time
they're supposed to read the voltage of
your system and set themselves properly
but because i had this switched off it
actually wasn't connected to the battery
at all and it defaulted to 12 volt
batteries which is obviously not right
and so when everything turned on i got
all sorts of errors and alarms and
everything went haywire and it took some
time for me to figure out what happened
thankfully these units are bluetooth
enabled so i was able to pull up an app
on my phone and get in there and change
the batteries the right type of
batteries and the system voltage to the
right voltage and once we got past that
then everything was good hey look at
that you have power it's been a long
road but by building this yourself
you've been able to save thousands and
thousands of dollars high five
[Music]
moving forward i want to set a few
expectations your bms is going to spend
some time
balancing your battery cells they're not
going to be perfect right out of the
gate in fact they may overheat they may
shut down for a couple of days if things
aren't set right and that's the other
thing is you're going to be constantly
tweaking these bms settings trying to
get them to work right the first few
months we had several shutdowns in the
dead of summer when we were running
multiple air conditioners and the
batteries were getting charged just a
little too much and the bms got too hot
and then the whole thing just shut down
and the vrm did its job and it sent
notifications and everything did what it
was supposed to but it was still very
frustrating so here's my advice to you
go ahead and just send an email to rec
bms i should have done this at the very
beginning and i don't know why i didn't
but i just sent them the spec sheets of
my batteries and said hey
something's not right with my my battery
charging settings because the bms is
getting too hot trying to balance these
cells
and they immediately reply back with the
exact settings and it's been perfect
ever since also not having the right bms
settings caused all sorts of other
issues when the system would shut down
and reboot then sometimes the wi-fi
module or the touch display wouldn't
reconnect and then sometimes it would
lose its connection to the internet and
it was just a whole thing so just get
those bms settings right just send them
an email it'll make your life much
easier
[Music]
as of this video we've had this system
running full-time for six months and we
couldn't be happier with the results
it's easy to throw around a bunch of
theoretical numbers but to actually have
that real world experience
has been amazing to see
this solar powered system running
silently in the background especially
once we got those bms settings figured
out because our house isn't built yet
we're still only using a fraction of
this system but right now our current
average is about 13 kilowatt hours
production and about 10 kilowatt hours
of consumption during the summer when
we're running multiple air conditioners
we've seen usage as high as 35 kilowatt
hours i'm excited to see how the system
performs once we're actually using it to
its full capacity because right now
we're filled back up to 100 by probably
8 or 10 o'clock every single morning
we're just scratching the surface on the
amount of solar power output this thing
can produce all in all this system is a
beast and we know that we paid probably
half of what all of our other neighbors
paid for their own off-the-shelf systems
and our system is probably two or three
times the capacity and i'm not saying
this to brag i'm just saying that it's
really cool how big of a system you can
build at such a small cost if you learn
how to piece all these components
together yourself plus if you build it
right you can switch out components and
grow as needed
[Music]
it's not all unicorn rainbows though
hindsight is always 20 20 and there are
a few things that we would do
differently so let's talk about those
real quick understanding alibaba's
payment and shipping methods
this whole process was very
uncomfortable for me i didn't understand
why they wouldn't take my credit card i
didn't understand why after i paid for
it they tried to give me a different
product and then i didn't understand why
it took so long to ship and why they
couldn't give me meaningful updates it's
a very different process for buying
something on amazon
but now that i know how that process
goes i'm okay with it because i saved a
ton of money on batteries but at the
time it was very stressful solar panel
wattage now yes we got a great deal on
our solar panels we mentioned that we
only spent 25 bucks a panel but here's
the thing that solar ground mount that
massive solar ground mount that we had
to build
cost almost five times as much as the
panels themselves so what we would have
done differently is we would have spent
more money on higher capacity panels
that should have been roughly the same
size and then built a solar ground mount
that was much smaller which would have
reduced that cost the only upside is
that now we have a huge solar ground
mount and if we want to replace with
those higher capacity panels we can
totally switch them out and do that down
the road smart solar battery voltage
like i mentioned i didn't have the right
things turned on when i flipped on the
solar charge controllers for the first
time and they couldn't read the battery
voltage and caused all sorts of problems
don't be like me make sure it can read
that battery voltage on startup bms
balancing settings and finally like i
said i really should have just emailed
rec a long time ago and gotten those
exact bms settings for my specific
battery cells would have saved me a lot
of stress those first couple of months
now you may be asking how much did this
all cost you keep saying it's like super
cheap but you haven't given me any
numbers well this thing got so long that
we're going to have to do the cost
breakdown in a separate article video
which should be coming soon but in the
meantime again that article that we've
linked to a few times in this video has
links to all the products in it so you
can go ahead and piece that together
yourself if you're in a hurry we'll come
back and we'll add a link to that video
and article when it's finished so make
sure you're subscribed so you know when
we put it out
[Music]
hey congratulations you made it through
our nerdiest video ever
i'm not sure how i keep talking myself
into making these really long detailed
nerdy posts and articles and videos it's
really good information and it's
something that we were looking for when
we tried to build our system so you're
just helping other people yeah speaking
of we have to take a minute and we have
to thank a few other people who came
before us because obviously there's a
ton of diy solar information out there
on the internet already and we were
inspired by a few important people
one is michelle and juan from beginning
from this morning who helped us build
our whole system piece it together and
helped us understand how it all worked
together not only that but they built
the battery box and i mean they did so
much to help us we could not have done
it without them also handyman and wild
wonderful off-grid for showing us how to
build the frame that our solar panels go
on yeah because like we said that was a
whole thing and they had some really
great videos that helped explain the
best way to do that and finally will
prows of diy solar systems he does super
deep dives on all sorts of lithium
batteries really great resource if
you're going to go down that road i hope
that this installation breakdown and
wiring diagram help you understand how
to build your own massive off-grid solar
power system in a way that's safe and
cost-effective and reliable now we are
just getting started here on the
off-grid homestead our house is not
built yet but that does begin this year
in 2022 so make sure you're subscribed
if you would like to see how all this
power will work for our house don't
forget we do have that full wiring
diagram for download if you want to
check that out and that cost breakdown
is coming very soon so again we hope
this was useful and we'll see you soon
[Music]
you