Every figure in this article comes from one source video — Rockhill farm's DIY Solar Generator - Save Thousands by Building Your Own, watched more than 750,000 times. Host Brock and his dad Keith take a $3,000 portable power station that Brock reviewed a week earlier, put it next to an empty wheeled box, and build a DIY replacement that delivers roughly 90% of the functionality for about 10% of the price. The numbers are unusually honest for a build video: they reuse two batteries that were already sitting on the farm, buy one $150 inverter, and end up spending ninety dollars out of pocket for the whole working setup. If you would rather watch the build before reading the breakdown, the video is right here:
What makes this build worth studying is that it is not a sponsored showcase. The video grew out of viewer comments on an earlier review — people said the reviewed unit was nice but they would never spend $3,000 on backup power — and the host built the cheap version in response, with his dad, using equipment that was already lying around. The result is a practical, serviceable solar generator with honest numbers: what it costs, what it runs, and where the money goes. Those same trade-offs — inverter first, battery second, expand over time — are exactly what we help customers balance at Dajiu Energy.
The host is fair to the retail unit before questioning its price. It is rated for 3,000 charge cycles, which means you could run it down and recharge it every day for roughly 10 years, and at the end of that decade the batteries are not dead — they may still hold about 80% of their original capacity. That is a genuinely long-lived product. But $3,000 is a lot of money, and the video's point is not that the retail unit is bad — it is that most people do not need to spend that much to cover the loads they actually have.
The host's dad is the proof. He has run backup power this way for decades on a small budget — a battery that was not being used, an inverter, a couple of lamps and a TV. His brother's wedding needed outdoor lights and music, which gave this build a real deadline: a cheap, portable way to supply electricity to an outdoor venue without buying a $3,000 machine. That is the exact scenario a budget solar generator is for — occasional but important power, delivered cheaply and reliably.
The build has two main parts and only one of them is new. The first part is an inverter — the device that turns 12V battery power into the 110V AC your appliances use. The dad had recently bought a 1500W inverter for about $150. The video also checks Harbor Freight and notes a 2000W unit at $170 — almost the same power for twenty dollars more — plus 2200W models for a few hundred. The host's advice is worth writing down: start with the inverter you will end up with, because you do not want to buy inverters twice as your needs grow; batteries are the part you add later.
The second part is two 12V lead-acid batteries that were already on the farm. One was mounted on a trailer to run a winch — used maybe two or three times a year — and the other came off a 1941 Model A tractor started a few times a year. The host makes a point that surprises a lot of people: letting a lead-acid battery sit unused is what ruins it. These two batteries were heading for failure precisely because they were not being used, and pressing them into service actually maintains them and makes them last longer. That single insight turns the cost of the batteries from "$150 each" to "free, and better for them."
The wiring is simple enough to show in one sentence: connect the two batteries positive to positive, negative to negative, then connect the inverter's positive to the positive bank and its negative to the negative bank. That is a parallel connection — the capacity adds while the voltage stays at 12V. The host connects the battery cables (the only thing actually purchased today) between the two batteries, and the setup produces power immediately when the inverter is switched on.
The comments section adds an important refinement the video only implies. Commenters with real electrical experience pointed out that when connecting the inverter to a two-battery bank, the inverter cables should land on opposite corners of the bank — positive on one battery, negative on the other. That way each battery carries roughly the same load, instead of one battery working harder. The same commenters noted that parallel charging works best when the batteries are the same chemistry, age and state of charge. On a budget build you use what you have, but matching the batteries as closely as possible is the right habit. The host also mounts everything in a wheeled plastic tote, drills a couple of holes, and zip-ties the inverter so it cannot slide around and short against the terminals.
This is the section where the video earns its trust, because the host actually tests loads and reads the inverter's watt meter. A cheap LED light draws so little it does not even register on the meter — around 1 watt. Then he plugs in a 9-amp drill: 849 watts at start-up, settling to 425 watts continuous — he had measured the same numbers earlier on a separate meter, about 800W surge and 400W continuous. The takeaway: even a modest 1500W inverter can start a demanding power tool because surge current is brief.
The video then runs the numbers for what most people actually need in an outage: LED bulbs under 10W each, a 55-inch flat screen TV at about 57W, an internet modem under 10W. Add a couple of lamps, the TV and the modem, and you can light and entertain a room for under 100W total — which a good battery will run for several hours. The dad's 20-year-old habit is the same math: a boat battery and an inverter powering a few lights, a TV and a modem through an outage, or tent-camping luxury with a light, radio and fan. When you know your loads in watts, sizing a battery and inverter becomes arithmetic instead of guessing.
A solar generator has to get its energy back, and the video shows three paths, in order of convenience. First, a regular battery charger — charge the batteries in the shop, exactly like charging any other battery. Second, your vehicle's jumper cables — the alternator charges the bank while the vehicle runs; crude but effective in a pinch. Third, solar panels, which is what makes it a solar generator. Solar panels are no longer expensive, especially for trickle charging: the host bought a 25-watt solar charger from Harbor Freight for this build and calls it plenty for a trickle charge. He has been maintaining two fuel-pump batteries for the last couple of years with a 7-watt version — enough to keep an idle battery topped up indefinitely.
Heavy users get a bigger path: the reviewed $3,000 unit shipped with two 200W panels (400W total), and Harbor Freight's 100W panel runs about $120–125, so 400W of charging costs roughly $500. Whatever path you choose, a charge regulator (charge controller) is required — this one cost $20 and regulates the panel's 14–18V output down to a safe constant voltage for the battery. Clips come with the panel, so hook-up is literally clip-on. For a permanent installation, that same controller concept scales to our larger off-grid storage systems.
The video closes with two honest cost scenarios, both compared against the $3,300-ish retail unit. Option one — basic build from nothing: at least $100 for a battery, $150 for an inverter of this size, a plastic toolbox and dolly around $50 — call it $350 for an inverter, battery and box. Add the solar panel ($70) plus its regulator ($20) and you are at $90 more, for a system that covers the base loads above. A second battery adds about $100. So the most basic version lands around $350 versus $3,300 retail — a saving of roughly $3,000, with the honest caveat that it is not as polished as the retail unit.
Option two — match the retail unit with lithium: LiFePO4 batteries at about $400–600 per 100Ah (two of them ≈ $1,000), a 2000W inverter under $200, 400W of solar ≈ $500, a better charge controller ≈ $70, a nice wheeled box ≈ $100 — total around $1,800, still about half the price of the retail unit with similar capability and a fraction of the weight. The video only spent $90 because the batteries and box were already owned. The lithium upgrade path matters for one reason: lithium weighs about a third as much and holds about twice the energy of lead-acid, which is exactly why modern portable power stations — and our LiFePO4 power stations — are built that way.
The build's most educational moment is a battery-care lesson hiding inside a cost trick. A lead-acid battery that sits low on charge corrodes its lead plates, and corroded plates short out — that is what kills an idle battery. Keeping it charged is the life of a lead-acid battery. The dad explains that both batteries in this build were on their way to being ruined by neglect, and the project effectively rescued them: putting them to work and keeping them charged maintains them.
There is a design lesson here for anyone running backup power. If your backup battery sits for months between outages, attach a trickle charger or small solar panel to keep it topped up — the host's 7W panel has maintained a pair of fuel-pump batteries for two years without a manual charge. If you would rather not think about maintenance at all, that is the real argument for a lithium battery: a LiFePO4 pack with a built-in BMS manages its own state, tolerates deeper discharge and sips only about 3% self-discharge per month. It costs more up front and removes the maintenance problem entirely — which is the trade-off the video lays out so clearly.
The video's answer is quietly practical: a DIY build makes sense when you want maximum power per dollar and you already have (or can find cheap) batteries, a box and a basic skill with a wrench. The $90 build proves the point — real backup power for less than a tank of gas. It makes less sense when you want a finished, warrantied, all-in-one unit that works out of the box with built-in metering and low-temperature protection, because those features cost engineering, and that is where the $3,000 units earn their price.
There is also a middle path most people never consider: buy the inverter once, and treat batteries as the expandable part. Start with one battery, add a second when you need more runtime, and upgrade the charging path over time. That is the exact modular logic behind every system we size at Dajiu Energy — whether a single 12V drop-in battery or a wall-mounted home storage bank, the architecture is the same and the expansion is bolt-on. Whichever way you go, the numbers in this video — under 100W for lights and TV, 425W continuous for a drill, $350 for a working backup — are the ones that matter.
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.
Source video: Rockhill farm — "DIY Solar Generator - Save Thousands by Building Your Own" (youtube.com/watch?v=upLh5uzpPkc). Comment excerpts are quoted verbatim from the video's top comments; where the creator replied, his words are quoted, otherwise answers are Dajiu Energy's own. Build figures and prices are transcribed from the video.
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