The short answer: a DIYer shared a huge home solar system with 70 panels (about 28 kW) and 62 kWh of battery storage. The builder said it cost about $20,000 for the major equipment, not counting labor or miscellaneous materials. Commenters were impressed, but many warned that most people will not get this price. The builder owns an electrical shop and likely bought at trade pricing.
Below, we break down what was built, why the $20K figure started a debate, which costs are usually missing from a headline number, and how to plan a project like this without nasty surprises. Whether you are dreaming of going off-grid or just curious how far DIY solar can go, this is what the build actually teaches.
What Did the DIYer Actually Build?
According to a report from The Cool Down, the system is far larger than a typical home installation. The equipment list works out to:
- 70 SEG solar panels, each rated at 405 watts
- Two EG4 18KPV inverters
- Two 31 kWh EG4 battery banks
Together, that adds up to roughly 28 kilowatts of solar capacity and 62 kilowatt-hours of storage. The original post's title reportedly said the builder was going 100% off-grid the next day, which is a big part of why the project drew so much attention.
| Component | Quantity | Details |
|---|---|---|
| Solar panels | 70 | SEG, 405 W each (about 28 kW total) |
| Inverters | 2 | EG4 18KPV |
| Battery banks | 2 | 31 kWh each (62 kWh total) |
| Reported cost | - | About $20,000 for big items only |
| Not included | - | Labor and miscellaneous materials |
kW vs. kWh: Understanding the Numbers
These two units confuse many first-time solar buyers, and the difference matters when you read a build like this one.
- Kilowatts (kW) measure power, or how fast electricity is produced or used at a given moment. The 28 kW figure describes the combined rating of the panels under ideal conditions.
- Kilowatt-hours (kWh) measure energy, or how much electricity is produced, stored, or consumed over time. The 62 kWh figure describes how much energy the batteries can hold.
A useful way to picture it: kW is like the speed of a car, and kWh is like the distance traveled. Real-world panel output is usually lower than the nameplate rating because of weather, panel angle, shading, heat, and system losses. So a 28 kW array will not deliver 28 kW all day. Actual production depends heavily on your location and the season.
For an illustration only, imagine a household that uses 40 kWh in a day. A 62 kWh battery bank could, in theory, cover a day and a half of that use without any solar input. Your own numbers will differ, which is why checking your utility bills comes first.
Is $20,000 a Realistic Price for 28 kW of Solar?
Not for most people. Some quick math shows why the number surprised readers. Spread over about 28,350 watts of panels (70 x 405 W), $20,000 comes to roughly $0.70 per watt. That single figure covers panels, inverters, and 62 kWh of batteries, and it excludes labor and everything else needed to finish the job.
When readers asked what the build had cost, the builder answered that it was about $20K for the big items, not counting labor or miscellaneous materials. One commenter cautioned others to set realistic expectations if they hoped to match that price. Another suggested the builder likely had wholesale access. The builder confirmed it, noting they own an electrical shop.
The takeaway is that the $20K figure is real, but it reflects an insider's purchasing power and free labor. It is not a benchmark for a typical homeowner shopping at retail.
What the $20K Does Not Include
A headline price for "the big items" leaves out many costs that add up quickly. In a separate report on DIY solar budgets, commenters described how smaller items inflated their totals:
- Mounting hardware: one builder said the mounts are what really add up.
- Copper wiring: another reported spending over $1,000 on PV wire alone and still needing more.
- Overall overruns: a third said they had probably spent about twice what they planned once everything was counted.
For a 70-panel array, racking, wire, breakers, disconnects, grounding, and conduit can be a large share of the real budget. One DIY guide from EcoFlow estimates that non-panel extras can run roughly $1,200 to $2,500 on a typical home project, with permit fees often falling between $300 and $1,000. That guide is aimed at ordinary-sized systems, so a build of this scale could easily cost more in those categories.
A budget checklist for the "hidden" items
- Racking, rails, and roof or ground mounts
- PV wire, battery cables, and conduit
- Combiner boxes, breakers, fuses, and disconnects
- Grounding and surge protection
- Permits, inspection fees, and utility paperwork
- Specialty tools such as crimpers and torque wrenches
- Professional review or sign-off by a licensed electrician
- Your own time, which is unpaid but not free
Why Trade Pricing Changes Everything
Electrical contractors and supply shops often buy in bulk and have accounts with distributors. That can lower the cost of panels, inverters, batteries, and small parts alike. They also already own the tools, know the code, and can do the labor themselves, so the parts that consume the largest share of a professional installer's quote are simply absent from their cost.
This is not a criticism of the builder. It is context. A homeowner comparing this build to a retail quote is not comparing like with like, and that gap explains most of the debate in the comments.
Who Can Realistically Copy This Build?
Good candidates
- People with electrical training or a licensed electrician on the team
- Owners of properties with plenty of roof or ground space
- Households with high, steady electricity demand
- Anyone able to source equipment at trade or bulk prices
Poor candidates
- First-time DIYers with no electrical experience
- Homes with modest energy use, where a system this size is overkill
- Areas with strict permitting or interconnection rules that have not been researched
Safety note: high-voltage DC wiring and large battery banks can cause serious injury or fire if installed incorrectly. Local code and utility rules also vary, so confirm what is allowed where you live before buying anything.
Battery Storage: Why 62 kWh Matters
Storage is what makes an off-grid or near-off-grid setup possible. Solar panels only produce during daylight, so batteries carry the household through evenings, cloudy stretches, and outages. A 62 kWh bank is many times larger than the single-battery systems many homes install, which is a big reason this build stood out.
Larger storage brings tradeoffs, though:
- Cost: batteries are often one of the most expensive parts of a solar system.
- Space and weight: big banks need a suitable, ventilated, code-compliant location.
- Safety: installation, fusing, and disconnects need careful design.
- Sizing: buying more storage than you can recharge with your panels wastes money.
The builder paired the batteries with a very large array, which helps keep them charged. Both halves of the system need to be sized together.
Should You Really Go 100% Off-Grid?
Going fully off-grid sounds appealing, but it removes the safety net of the utility. In some places, staying connected offers benefits such as backup when the batteries run low and, where allowed, credit for excess power. In other places, going off-grid may be the only practical choice for a remote property.
Questions worth asking before you decide:
- How much power do you use during your worst month, not your average one?
- What is your plan for a long stretch of poor weather?
- Do you have a backup generator or another fallback?
- Does your local authority permit a fully disconnected home, and what inspections apply?
- Does your insurer have requirements for solar and battery installations?
How to Budget for a Large DIY Solar Project
- Start with your usage. Review 12 months of utility bills to find your real kWh consumption.
- Size the system to the need. More panels are not automatically better if you cannot use or store the power.
- List every component, including racking, wire, breakers, disconnects, grounding, and monitoring.
- Add a contingency. Given the overruns commenters described, an extra cushion is sensible.
- Check permits and inspection requirements with your local authority and utility.
- Verify current incentives. Federal and state solar incentives have changed in recent years, so confirm what applies to your project this year before counting on a tax credit.
- Get comparison quotes from local installers, even if you plan to DIY, so you know what you are actually saving.
Lessons Any Homeowner Can Take From This Build
- Headline prices rarely tell the whole story. "About $20K for the big items" is a very different claim from "the whole system cost $20K."
- Professional access is a real advantage. Trade pricing and existing skills can cut costs dramatically.
- Small parts add up. Wire, mounts, and connectors caught other builders off guard.
- Size matters, but fit matters more. A system should match your usage, roof space, and budget, not just impress commenters.
- Get expert eyes on the plan. Even confident DIYers benefit from a code review before energizing anything.
Frequently Asked Questions
How many panels did the DIYer install?
Seventy SEG panels rated at 405 watts each, for about 28 kW of capacity.
How much battery storage does the system have?
62 kWh, from two 31 kWh EG4 battery banks paired with two EG4 18KPV inverters.
Did the whole project really cost $20,000?
The builder said about $20K for the big items only. Labor and miscellaneous materials were not counted, so the true total is higher.
Why did commenters doubt the price?
Similar equipment often costs much more at retail. The builder later said they own an electrical shop, which likely means trade pricing.
What is the cost per watt of this build?
Dividing $20,000 by roughly 28,350 watts gives about $0.70 per watt, but that covers only the major equipment, including batteries, and not labor or extras.
Can a beginner build a system this large?
It is not advisable without electrical expertise. Systems of this size involve high-voltage wiring, code compliance, and often inspections. Consider hiring a licensed electrician at least to review and sign off on the work.
Do I need permits for a DIY solar system?
In most places, yes. Requirements vary by city, county, and utility, so contact your local building department before you buy equipment.
The Bottom Line
This build is impressive, and it shows what a skilled, well-connected DIYer can do. But the $20K headline covers only major equipment and reflects insider pricing. If you are planning your own project, budget for the "little things," verify local rules and incentives, and compare your plan against real installer quotes before you commit.
Next step: read the original report, then review your own electricity bills to see what size system you would actually need.