Where This Guide Comes From
This walkthrough follows Martin Johnson's off-grid solar battery bank install on his homestead in North Idaho, a build that has passed 2.3 million views. He and his family started out in tents on bare land and have been putting the place together themselves ever since, which is the reason the video is worth watching rather than skimming: nothing in it was installed by a contractor with a van full of specialised tools. He opens sixteen batteries, mounts two charge controllers and two inverters on a shed wall, makes every battery cable by hand, and then flips the switch on camera.
The system replaces a 24V setup that had been running the house on eight of the same batteries with two small controllers and two 3,000W inverters, all of it crammed into a camping tent he cheerfully calls the hillbilly solar shed. The upgrade doubles the battery count, doubles the system voltage and roughly quadruples the inverter capacity. If you have been wondering when it is time to stop adding batteries to a 24V bank and start over at 48V, this build is the answer in hardware form.
Why 48V Instead of 24V
The move from 24V to 48V is the decision that shapes everything else in the video, and the reasoning is the same one that applies to any expanding off-grid system: at a given power level, doubling the voltage halves the current, and current is what costs you copper, heat and voltage drop.
The practical evidence is in the inverter spec. Two Victron Quattro units rated 5,000W each, running at 48V, are stacked to produce 240V split phase and about 10,000W total. Trying to reach that number on a 24V bank would mean something in the neighbourhood of 400A at full load, which is a cable and breaker problem long before it is a battery problem.
Sixteen 100Ah batteries at 12.8V nominal works out to roughly 20kWh of stored energy on paper. That is a house-sized bank, and house-sized banks belong at 48V. Our wall-mounted and stackable storage units follow the same logic — once you are past a certain capacity, the system voltage goes up because the alternative is a very thick cable run.
Eight New Batteries, Four Series Strings, One Bank
The bank is built from sixteen 100Ah lithium iron phosphate batteries: eight new ones and eight already in service. The wiring is the part worth copying.
Each group of four batteries is wired in series, positive to negative down the line, which turns four 12.8V units into one 48V string. Four of those strings then go in parallel — negative to negative, positive to positive — producing one large 48V bank. This is the 4s4p arrangement, and it is why the shelf holds sixteen batteries while the system still speaks a single voltage.
He notes something that is easy to miss on camera: the batteries can be mounted in any orientation. No venting, no electrolyte to spill, nothing that has to stay upright. That freedom is a genuine LiFePO4 advantage over flooded lead-acid, and it is what makes a wall-mounted stack practical in a shed with limited floor space.
One thing he does not do, and a lot of viewers noticed: he stacks the batteries directly on top of one another with no gap between the rows. More on that in the comment section below, because it turned into the most discussed detail in the video.
Mounting the Gear: MPPT, Lynx Distributor and Shunt
With the bank on the wall, the equipment goes up in a deliberate order: charge controllers on one side, busbars and shunt in the middle, inverters above.
The charge controllers are Victron MPPT units rated for 450V input and 100A output. The 450V ceiling is the interesting number, because it lets you put a lot of panels in series. Series panels raise voltage and lower current for the same wattage, which means the cable from the array to the controller can be 10 AWG instead of something the size of a garden hose. He is running somewhere around 300V from the roof into those controllers, and he lays out four separate PV inputs across the two units — two strings per controller.
Two Lynx Distributor units serve as the DC busbars. They bolt together into what is effectively one fused busbar pair, and they carry the heft you would expect: solid copper, rubber covers, and a data cable so the components can talk to each other.
The battery shunt goes on the negative side, as close to the battery as the cable allows. Everything else — every load, every charger — connects downstream of the shunt, because anything wired ahead of it will be invisible to the monitor and your state-of-charge readings will lie to you.
A surge protector sits on the same negative side, and a Victron Cerbo GX with its small display gives him Wi-Fi and Bluetooth access to the whole system. He can watch charge current, load and battery state from the house or from anywhere else, which for an off-grid build is less of a gadget and more of a diagnostic tool.
Making Battery Cables That Don't Fail
The cable section is the most useful ten minutes in the video for anyone building a bank, because it shows a method that costs very little and produces joints that hold.
He needs twelve short cables to series-connect the batteries, all of them 2 AWG. The cable is cut with a proper cutter rather than a hacksaw, and the reason matters: a clean square cut lets the strands sit flat inside the lug, while a ragged cut leaves stray copper that will not fit and will not compress evenly.
Stripping is done with a knife, carefully, working around the jacket rather than into it. The copper strands in this size of cable are thin, and nicking them at the strip line creates the stress point where the cable eventually breaks.
The lugs go on with a hammer-style crimper — open it, drop the cable and lug in, seat it with a couple of taps, then drive it home against something solid. He uses a tree stump. You will hear the crimp stop moving when it is fully set. Hydraulic crimpers and soldered lugs both work; this one is cheap and repeatable, which is the point.
The detail most people skip: pre-bend the cable before crimping. Once a short cable has two crimps on it, it goes stiff, and trying to shape it afterwards puts stress right at the lug. Bend it first, then crimp, then slide heat-shrink over the barrel.
Two Inverters for 240V Split Phase
The inverters are the heaviest part of the job, literally. Each Quattro is a 5,000W 48V unit, and they are mounted high on the wall on hanger brackets, which he manages to do alone and does not recommend doing alone.
The pair is configured as master and slave over a data cable and set to run split phase, producing 240V between the two hot legs and 120V from either leg to neutral. That is what lets a normal American house panel work: 240V for the big loads, 120V for everything else.
The AC side is wired in two directions. Generator input comes in on AC-in from a 240V generator, there to recharge the bank during long cloudy stretches. AC-out feeds a small distribution panel with a 50A breaker to the house and a 20A breaker for the shed outlets and lights. From there the feed runs underground to a standard residential panel, which is fed entirely by the battery bank — no grid connection at all.
Bringing the Solar Array In
Current array: six panels in one place and four in another, adding up to roughly 3,000W. Sixteen more panels are planned, which will bring the total to somewhere between 5,500W and 6,000W.
For now, two PV cable pairs come through a drilled hole in the shed wall and land on the first controller: PV1 and PV2. Positive gets red tape at the far end so there is never a moment of guessing. The other two inputs stay empty until the additional panels arrive, at which point eight panels go in series on one input and eight on the other.
He is careful to point out that the array was disconnected during this work, so the cables carried no voltage while he handled them. That is the habit worth copying — dead conductors, tagged conductors.
Grounding, First Power-Up and the Voltage Check
The near-miss in the video is the grounding. He walks through the whole DC and AC side, reviews every connection one more time, and then realises he was about to power up with nothing bonded. Four components need a ground: the two inverters, the charge controllers and the distribution. A ground conductor ties them together and then runs outside to a ground rod.
With that fixed, the switch goes on. No sparks, no smoke. A multimeter across the bank reads 53V, which is what a fully charged 48V LiFePO4 bank looks like at rest. The inverters boot, the Cerbo display comes alive, and the AC output measures 240V leg to leg and 120V from each leg to neutral. Both readings correct on the first try.
Then the house breaker goes on and the system picks up a real load.
First Loads and What the Numbers Looked Like
The first measured load is small and completely believable: about 229W total, split roughly 150W on one inverter leg and 69W on the other. Lights, a fridge cycling, standby draw — the sort of base load an efficient off-grid house actually carries most of the day.
Then the solar switch goes on. With a sunny sky, the array puts about 2,300W into the controllers, the bank takes roughly 2,000W of charge, and the AC loads pull about 241W at the same time. The display shows the flow: PV in, battery charging, inverter out.
Those three numbers together tell you more about whether a system is healthy than any single reading. Charge current above load means the bank is gaining. Charge current below load means it is losing, whatever the sun is doing.
Lithium vs Lead-Acid: The Capacity and Maintenance Difference
The video is sponsored by Battle Born, and he makes the comparison plainly: a 100Ah flooded lead-acid battery should not be discharged below about 50%, so you get 50Ah of usable capacity. A 100Ah LiFePO4 battery can be taken down to empty without damage, so you get the whole 100Ah.
Same label, twice the usable energy. That arithmetic is the reason so many off-grid builds have switched chemistry, and it is why comparing amp-hour stickers across chemistries is close to meaningless. Compare usable watt-hours instead.
The maintenance side is just as practical. No watering, no venting, no equalisation charges, no terminals turning green. Each battery carries its own BMS that cuts charging when the cells get too cold and stops discharge before they are over-drained, so the protection travels with the battery rather than living in a separate box on the wall.
For anyone sizing a first bank, the takeaway is that the chemistry decision and the voltage decision are separate. Pick LiFePO4 for the usable capacity and the low maintenance, then pick 12, 24 or 48V based on how much power you intend to move — the sizing and wiring guides here walk through that side of it.
And if you're not hunting for a consumer brand but need the battery itself — a custom LiFePO4 pack at a specific voltage and capacity, an OEM or ODM project, or wholesale supply for your own power station line — that's what we do. Dajiu Energy is a Chinese manufacturer building LiFePO4 batteries for RVs, homes, golf carts and portable applications since 2017. Our product range covers LiFePO4 drop-in replacement batteries, EV and golf cart batteries, wall-mounted home storage, portable power stations, commercial energy storage and battery swap cabinets — explore the full lineup in our product center, or browse more buying guides. Tell us your voltage, capacity and size, and we'll engineer the pack to hit it.
What Viewers Are Asking (Top Comments on the Video)
The comments under this video split into two camps: people impressed by the wiring, and people worried about the shelf. Both are worth reading, because both point at things a first-time builder should think about before copying the build. The creator did not reply to these threads, so the answers below are ours.
Source video: Martin Johnson - Off Grid Living — "EASIEST Off Grid Solar Power System Battery Bank" (2,396,163 views). Component ratings, wiring layout and start-up measurements are quoted from the build shown in the video. Comment text is quoted as posted; answers are Dajiu Energy's own.