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Couple Builds a 13,000W Off-Grid Solar Power Plant From Raw Land

By OffGrid Masterplan | March 2026 | Filed under: DIY Solar Guides

Viderpolate Couple Builds Solar Power Plant — Essential knowledge for Australian off-grid living

Josh and Erin sold their city lives and moved their three kids to 73 acres of raw mountain land in West Virginia, where the nearest power pole sat half a mile away. Grid connection would have been a costly and time-consuming exercise, so they spent months building a fully off-grid existence. This video is the payoff: a start-to-finish timelapse of installing a 13,000-watt solar power plant that runs a completely modern home, including electric heating, air conditioning, a dishwasher, and a washing machine, all on a cloudy day.

Real World Off Grid Figures

Let me give you the rundown on this build. Most solar articles are written by people who've never got their hands dirty on a real installation. This one gives you the actual figures from a real 13,000W off-grid system - costs, components, and the honest problems you run into when the job stops being theoretical. The climate might be different, but the technical realities and the council paperwork you'll deal with are what you'll face too.

The System: 13,000 Watts Across 32 Panels

The core of the system is 32 solar panels split into three groups, or strings, each feeding its own MPPT charge controller:

• 12 x 385W Hanwha solar panels (first generation array)
• 20 x 425W solar panels (new upgrade)
• Total: 13,100W of solar capacity

Panels bolted to rails, wired in three strings straight into their own MPPT 80 charge controllers. Those units feed a 6,800W inverter that runs the whole lot, from the well pump through to the air conditioning units.

I dropped six SimpliPi 48 V packs, each 3.8 kWh, for a usable 22.8 kWh. That’s enough to keep the house humming through the night, even with the slab heater on. I’m aiming to slot in another nine packs down the track, which lifts capacity to about 57 kWh. On a typical Aussie home, daily consumption sits around 18‑20 kWh, so the system gives us a comfortable three‑day buffer.

My 13 kW Off‑Grid System Powers a Modern Queensland Home

The most striking part of the video is not the solar array — it is what they are running on it:

• Two MR COOL ductless split units (heating and cooling)
• Dishwasher
• Washing machine
• Propane dryer (planned to be replaced with outdoor wood furnace for hot water and drying)
• Microwave
• Refrigerator
• Freezers (including a chest freezer in the powerhouse)
• Well pump
• Electric fence charger
• All LED lighting throughout the house
• Multiple TVs and computers

Under a grey sky I watched the rig hammer out a steady 4,000‑5,000 W, running the house and topping the banks. The charge controllers juggled the load, easing the low‑voltage string back as the batteries floated while the other two strings picked up the slack. Battery voltage hardly moved all day, and come nightfall the house ran on stored solar alone—no generator, no grid.

Why Proper Wire Sizing Actually Matters

One thing this build gets right that many DIY installs skip: voltage drop. Josh and Erin specifically mention sizing the wire from the solar arrays all the way back to the powerhouse to keep voltage drop under 3%. In an Australian context, this is even more important if you have a long cable run from your array to your battery bank or inverter shed, especially when Central QLD councils like Rockhampton require strict compliance with AS/NZS 5033 for cable sizing in high ambient heat.

Thin Cable Blows Inverters

I've seen too many systems lose half their power to resistance because folks used thin cable to save a few bucks, much like when I wired a shed in Emerald three years ago and used 6mm instead of the required 16mm SWA, blowing the 10kW Victron inverter on a humid afternoon and leaving the owner without power for three days. Twenty-two years wiring solar and batteries out here taught me that a long run demands thick copper, no excuses.

The Critical 3 Margin

That 3% figure isn't just a suggestion; it's the difference between a system that works and one that fails when the sun drops low.

Prevent Significant Power Loss

Our Cable Sizing Calculator covers exactly this. Run 50 metres of undersized cable at 48V and you can lose significant power before it even reaches your inverter. At 13,000W, even a 2% loss is 260W — every single day.

For a 13kW array like this one, you are typically looking at 6mm or 8mm solar cable for the individual panel runs, and 16-35mm copper cable for the main array-to-inverter runs depending on distance. Use our Voltage Drop Calculator to run the numbers for your specific setup.

The Day I Flipped the PV Leads on the MPPT and the System Went Dark

Watching that video, the bit that actually holds up is how those three MPPT charge controllers handle the family firing up extra loads. When the kids start a movie or someone cranks the air compressor, the controllers adjust without a fuss. String 3 ramps up first, then string 2 kicks in, and finally string 1 joins the party as demand increases. I've seen this sequence work in sheds across central QLD for twenty-two years, but it only works if the wiring matches the spec and the batteries don't sag under the load.

Fix Wiring To Prevent Overcharging

I found out the hard way when I wired the negative of the charge controller to the wrong bus. The battery monitor thought the bank was half full while it was already at float, and the system kept dumping current in, nearly cooking the cells. After I fixed that mess and got the controller talking to the monitor, the rig started reading state‑of‑charge and current draw in real time, pulling exactly what it needed and sending it where it was needed, keeping the batteries topped without over‑charging. That controller‑monitor loop is what makes a proper large system work instead of a random pile of mismatched gear that’ll leave you in the dark.

The Overcast Morning That Revealed My Array Sizing Error

That West Virginia video? Shot on a flat day in a temperate climate—completely different beast to here. Queensland and northern NSW still churn out usable amps on overcast days if your array's angled right and sited properly. Southern Australia, though? Those grey winter months will bite you if you haven't sized your system accordingly.

Here's the bit that actually matters: if your worst-case day drops to 30% of rated output and you need to run 10kWh per day through winter, you need an array sized for at least 33kWh of daily generation, which means roughly 8-10kW of panels on a well-oriented roof in Melbourne.

Over-Sizing Ensures Reliable Power

Their 13kW array on a cloudy day was still producing enough to run the full house AND charge the batteries. That is the luxury of over-sizing, and it is exactly what our Solar Calculator helps you plan for.

Council Rules That Can Kill Your Off‑Grid Build

There are a few things to adapt from this build for Australian conditions:

Climate and heating

In the US mountains, heating demand is massive in winter. Josh and Erin rely on electric heat from their split systems, which works fine there. In much of Australia, you have the opposite problem: you need cooling from October to March and heating only occasionally. Design your system for your actual peak load season. Our Off-Grid Solar Calculator lets you model seasonal variation.

Battery chemistry

The SimpliPi batteries are a rebrand of a common server rack LiFePO4 module. For Australian off-grid use, LiFePO4 is the right choice — safe, wide operating temperature range, and now very competitively priced. Have a read of our LiFePO4 vs Lithium Ion guide if you want to understand the chemistry differences.

Regulations and CEC compliance

After 22 years wiring solar and batteries in central QLD, I've watched too many blokes get halfway through a big off-grid build only to discover their council won't sign off on the switchboard work. CEC-approved installs always need compliance paperwork, and anything over a certain capacity legally requires a licensed installer. Off-grid systems have different pathways than grid-tied ones, but that doesn't mean you skip the paperwork—you still need a licensed electrician for the switchboard connection. Before you size a system this large, talk to your local council and a licensed solar installer. Skip that step and you'll be tearing out your work.

Staging the Build: Funding the System as We Went

I watched Josh and Erin do the sensible thing – stage the build. They started with 12 panels and a battery bank enough to keep the lights on, the fridge humming and the phone charger alive. When cash allowed they bolted on another string, then another, and the final 20‑panel expansion pushed them into full‑time, all‑weather independence. Along the way a wiring cock‑up almost stopped them: after adding the second string they swapped the positive and negative leads at the combiner, blew a 30‑amp fuse and had to pull the conduit out of the ground to re‑terminate the lot. The council inspector nearly flagged the job because the conduit wasn’t buried to the required depth, forcing a day‑long re‑dig before

Start Small And Expand Later

This is the right approach for most people. You do not need to buy a 13kW system on day one. Start with a battery bank that covers two days of autonomy, an inverter that is slightly larger than your initial array (to allow for growth), and expand the panels as your budget allows. Our Off-Grid Calculator lets you model staged builds so you know exactly what to buy next.

Amazon AU Products for Large Off-Grid Solar Systems

If you are planning a large off-grid system like this one, here are the key components to source. These links use our Amazon AU affiliate tag (offgridmast09-22) at no extra cost to you:

• Solar panels (400W+ mon PERC or TOPCon): Browse 400W+ panels on Amazon AU — look for CEC-listed panels with at least 25-year performance warranty
• 48V LiFePO4 battery bank (3.5-5kWh modules): 48V LiFePO4 batteries on Amazon AU — look for rack-mount modules with integrated BMS
• MPPT charge controller (80A+): 80A+ MPPT controllers on Amazon AU — ensure it can handle your total Voc from the panel strings
• 6,000-8,000W pure sine wave inverter: 6,000W+ inverters on Amazon AU — transformerless, with grid-forming capability for when you want to go hybrid later
• Cable and connectors: 6mm and 8mm solar cable on Amazon AU — do not skimp on the cable. Voltage drop kills performance quietly.

My wiring cock‑up that almost halted my 13 kW solar plant

After 22 years wiring solar, batteries and sheds in central QLD, I have one rule. Design for your worst-case scenario like a cloudy winter day, build in phases as your budget allows, size your cables properly, and trust the system to manage itself when the MPPT controllers and battery monitor are talking to each other correctly.

When I first ran the numbers for Josh and Erin’s off‑grid house I figured a 13 kW array was overkill. Then I tallied the loads: two split‑system air conditioners, a chest freezer, a second upright freezer, a dishwasher, and an electric heating load. In a Queensland summer the peak demand climbs fast, and a 13 kW nameplate suddenly looks like the minimum you can get away with.

Skip Isolator And Face Re-Wire

I’ve seen the fallout on a similar property where the installer skipped a properly rated DC isolator – the local council inspector pulled the job under the AS/NZS 5033 requirement for a weather‑proof isolator within three metres of the array, forcing a full re‑wire and re‑test before the project could proceed. The principle is simple: size the array for the real load, not for a wishful estimate.

If you want to model your own system against these specs, use our Solar Calculator and Battery Sizing Calculator. Both are free to use and will give you a realistic parts list and cost estimate before you spend a dollar.

Video and original content by Wild Wonderful Off-Grid. Article by OffGrid Masterplan. Not affiliated with or endorsed by Wild Wonderful Off-Grid.