A permitted, inspected, signed-off 3.2kW standalone solar system on your property. Eight 400W panels in a single series string, an off-grid inverter/charger, a 5kWh LiFePO4 battery, and a single 120V outlet. Not connected to the grid. Not connected to the utility. Standalone — on your shed, garage, or workshop.
This is the real thing. A minimum viable code-compliant standalone installation that runs real loads, passes inspection, and puts you in control of your own power. One permit, two inspections, signed off, done. Nobody comes back. Nobody bills you monthly. It’s yours.
If you built the 200W starter system, you already know how solar works. This is the upgrade — permits, AC output, full code compliance, grounding, labeling. Everything the 200W system wasn’t, this system is. And it can actually run your tools, your fridge, your lights, your shop.
Daily generation in Oregon: roughly 9.6 to 12.8 kWh per day (3,200W x 3 to 4 peak sun hours x 0.80 system derate). That’s real energy, every day, from your roof.
Through your single 120V outlet:
One outlet is intentional. It’s the minimum complete circuit the inspector needs to see — generation, storage, conversion, disconnection, utilization. You can add more outlets later. Start with one, get signed off, and expand from there.
This is paperwork, not a battlefield. The inspector wants you to pass. Here’s how to make it happen.
You — the homeowner. Owner and occupant of the property. Not renting it out, not flipping it. You do the work yourself. Oregon law gives you that right.
Your local building department. In Portland, that’s the Bureau of Development Services (BDS). Residential electrical permits can be filed online or in person.
A few hundred dollars. Contact your local building department for exact fees.
The permit expires if you don’t start work within 180 days, or if you stop work for 180 days. Each passed inspection resets the clock. Don’t let it lapse.
Two. That’s it.
8x 400W monocrystalline panels, series wired (single string).
Typical specs per panel:
| Spec | Value |
|---|---|
| Open-circuit voltage (Voc) | ~41V |
| Short-circuit current (Isc) | ~13A |
| Maximum power voltage (Vmp) | ~34V |
| Maximum power current (Imp) | ~11.8A |
String electrical characteristics (8 panels in series):
| Parameter | Calculation | Result |
|---|---|---|
| String Voc | 8 x 41V | 328V DC |
| Temperature-corrected max Voc (-15 C) | 328V x 1.14 | 374V DC |
| String Vmp | 8 x 34V | 272V DC |
| String Isc | Same as single panel | 13A |
Listing requirement: UL 61730 or UL 1703. Every panel from a reputable manufacturer carries this — Canadian Solar, REC, QCells, LONGi, JA Solar, Trina. Printed on the panel label.
Prioritize American-assembled panels where available. Check manufacturer filings for factory locations and domestic content. The panel market is changing — more American assembly capacity is coming online. If you can get American-made at competitive pricing, do it.
Why 400W: Market sweet spot. Good output, manageable size (6.8’ x 3.4’, about 50 lbs), widely available, competitive price. Single string of 8 gives you a clean voltage window (272V to 374V) that fits prosumer inverter MPPT ranges.
Off-grid inverter/charger: one unit that takes high-voltage DC from your panels, charges the battery, and outputs 120V AC to your outlet.
Critical specs:
| Requirement | Spec |
|---|---|
| MPPT voltage window | Must accept 272V to 374V DC range |
| AC output | 120V single-phase |
| Continuous power | 3,000 to 3,500W |
| Listing | UL 1741 — non-negotiable |
Reference products: EG4 6000XP, Victron MultiPlus/Quattro, Sol-Ark, Growatt SPF series. Starting points for research. Verify UL 1741 listing on the specific model before you buy.
Mount inside the structure. Adequate ventilation, manufacturer-spec clearance. Bond the enclosure to the grounding system.
5kWh LiFePO4 (48V 100Ah server rack battery).
| Requirement | Spec |
|---|---|
| Chemistry | LiFePO4 (Lithium Iron Phosphate) |
| Capacity | 5kWh (48V x 100Ah) |
| Listing | UL 9540, UL 9540A, or UL 1973 |
| Communication | CAN bus or RS485 — confirm inverter compatibility |
Why LiFePO4: No hydrogen gas, built-in BMS, 3,000 to 6,000+ cycle life, thermally stable. Safest lithium chemistry on the market.
Why 5kWh: Enough for overnight lights and small loads. One unit, simple. Expandable later by adding another in parallel. Start practical, grow as needed.
Reference products: SOK 48V 100Ah (UL 1973), EG4 LL series (UL listed), Victron Lithium Smart (UL listed). Verify listing and inverter communication compatibility before purchasing. Check country of origin on all components.
Installation: DC disconnect or breaker between battery and inverter. DC-rated overcurrent protection. Accessible for inspection. Labeled with voltage and chemistry. Standard shed ventilation is fine for LiFePO4. Secure against tipping.
This is where most DIY systems fail. Every piece of metal that could become energized during a fault needs a low-impedance path to ground. Skip this and you’re not just failing inspection — you’re building something dangerous.
Equipment grounding:
Grounding electrode system:
Everything you need, with specs and listing requirements. No affiliate links — just the specs so you can source the best deal from whoever earns your business.
| Component | Specification | Listing | Approx. Cost |
|---|---|---|---|
| 400W Monocrystalline Panel (x8) | Voc ~41V, Isc ~13A | UL 61730 | $800-1,200 |
| Z-Bracket Panel Mounts (8-panel set) | Universal roof mount | — | $60-120 |
| PV Grounding Lugs (x8) | Serrated contact | UL 2703 | $16-40 |
| Component | Specification | Listing | Approx. Cost |
|---|---|---|---|
| 10 AWG PV Wire, Red (100ft) | USE-2, UV-rated, 600V | UL | $30-50 |
| 10 AWG PV Wire, Black (100ft) | USE-2, UV-rated, 600V | UL | $30-50 |
| 600V DC Disconnect Switch (30A) | NEMA 3R, DC-rated | UL | $40-80 |
| EMT Conduit, 3/4” (10ft sticks, x2+) | Galvanized, exterior runs | UL | $15-30 |
| Component | Specification | Listing | Approx. Cost |
|---|---|---|---|
| Off-Grid Inverter/Charger | 3,000-6,000W, MPPT 120-500V DC, 120V output | UL 1741 | $1,200-1,800 |
| Component | Specification | Listing | Approx. Cost |
|---|---|---|---|
| 48V 100Ah LiFePO4 Battery | 5kWh, server rack, CAN bus/RS485 | UL 9540 or UL 1973 | $1,500-2,500 |
| DC Battery Fuse/Breaker | DC-rated, per battery specs | UL | $20-40 |
| Component | Specification | Listing | Approx. Cost |
|---|---|---|---|
| 12 AWG NM-B (25ft) | AC branch circuit, 20A | UL | $15-25 |
| 120V AC Disconnect/Breaker (20A) | Standard AC | UL | $15-30 |
| 20A GFCI Duplex Outlet (NEMA 5-20R) | NEC 210.8(A) | UL | $15-25 |
| Electrical Boxes + Cover Plates | Standard residential | UL | $10-20 |
| Component | Specification | Listing | Approx. Cost |
|---|---|---|---|
| 6 AWG Bare Copper Wire (25ft) | GEC | — | $25-40 |
| 10 AWG Green/Bare Copper Wire (50ft) | EGC | — | $20-35 |
| Ground Rods, 8ft copper-clad (x2) | Min 6ft separation | UL | $20-30 |
| Ground Rod Clamps, acorn (x2) | For 6 AWG conductor | UL | $8-15 |
| Component | Specification | Approx. Cost |
|---|---|---|
| PV Warning Labels (set) | Pre-made, UV-resistant | $15-30 |
| Label Maker | Brother P-Touch or similar | $30-50 |
The 30% federal ITC reduces that. A $5,000 system becomes $3,500 after the tax credit. That’s your tax dollars coming back to you. See Incentives for the full breakdown.
Buying advice: Order all 8 panels in one shipment — freight is a major cost, and matched panels from the same batch have consistent electrical specs. Confirm UL listings before ordering. Stick with known manufacturers for inverter and battery — that’s where the money is and where cutting corners costs you. Buy extra wire and fuses.
Full connection map, panels to outlet:
Panels (8x series) -> PV Wire (10 AWG) -> DC Disconnect (600V, 30A) -> Inverter MPPT Input -> Battery OCPD -> Battery -> Inverter AC Output -> AC Disconnect (120V, 20A) -> GFCI Outlet (NEMA 5-20R)
| Circuit | Wire Type | Gauge | Notes |
|---|---|---|---|
| DC source (panels to inverter) | PV Wire / USE-2 | 10 AWG min | UV-rated, 600V, exterior |
| Interior DC | THWN-2 in conduit | 10 AWG min | Transition at listed junction box |
| AC branch (inverter to outlet) | NM-B | 12 AWG | 20A circuit, interior |
| Battery to inverter | Per manufacturer specs | Per spec | Short run, heavy gauge |
| EGC | Bare/green copper | 10 AWG min | Continuous through all panels |
| GEC | Bare copper | 6 AWG | Protected from damage |
Required by NEC 210.8(A) for accessory buildings. Use a GFCI receptacle or GFCI breaker. Common inspection failure. Costs $15. Just do it.
Labeling is where DIY systems most commonly fail inspection. It’s easy, it’s cheap, and it’s the difference between a pass and a “come back next week.”
DC disconnect:
AC disconnect:
Conduits/raceways with PV circuits:
Inverter:
Battery/ESS:
Power source directory (NEC 710.10):
Warning labels:
Durable, weather-resistant, UV-resistant, legible. Per NEC 110.21(B).
Fifteen steps. Do them in order. Take your time. Getting this right the first time is the whole point.
1. Prep workspace. Clear the area. Post your line diagram. Lay out all materials and tools. Verify the full BOM is on site.
2. Pull permit. Application, site plan, line diagram, spec sheets. Pay the fee. Post the permit.
3. Mount panels (two-person job). 50 lbs each, awkward in wind. Late afternoon or overcast days are easier. Verify layout matches site plan.
4. Install grounding lugs on every panel frame. One UL 2703 lug per panel, serrated contact biting through anodization.
5. Run PV wire from array to equipment location. 10 AWG PV wire through EMT conduit. Service loops at both ends.
6. Drive ground rods. Two 8-foot rods, 6 feet apart minimum. 6 AWG copper GEC, listed acorn clamps.
7. Install inverter and battery. Mount inverter on wall. Set up battery rack. Ventilation, access, room to work.
8. Install DC disconnect. 600V DC-rated, between array and inverter.
9. Wire DC side (disconnect stays OFF). PV wire to disconnect input, disconnect output to inverter MPPT. EGC from panel lugs through daisy chain to inverter ground to electrodes.
10. Wire battery (don’t connect yet). Install battery OCPD. Run cables to inverter battery input. Battery breaker stays open.
11. Wire AC side. Inverter out -> AC disconnect (20A) -> 12 AWG NM-B -> GFCI outlet. Staple NM-B per code.
12. Install all labels. Every label. Right now. Before the inspector shows up.
13. Call for rough-in inspection. Permit posted, spec sheets ready, line diagram visible.
14. After rough-in passes: energize and test. Battery first. Verify inverter sees it. Then DC disconnect ON. Check MPPT voltage. Check AC output at outlet. Test GFCI.
15. Call for final inspection. Everything complete, everything labeled, everything grounded, everything listed. Pass this and you’re done.
Run through this yourself before calling the inspector.
You have a permitted, inspected, signed-off system. Legal, safe, yours. No monthly bill. No utility involvement.
This is a foundation, not a limit:
The 30% federal ITC applies. See Incentives for the tax credit math.
If this feels like a big step, start with the 200W system. It’s one afternoon, one panel, and it teaches you everything you need to know before going bigger.
For deeper technical context: batteries, inverters, string design, wiring and safety.
Run your numbers. See what the utility company doesn’t want you to know. Get your free energy audit.
DATA SOURCED FROM: Oregon Revised Statutes (ORS 479.540, 479.560), Oregon Administrative Rules (OAR 918-309-0000), Oregon Residential Specialty Code (ORSC R105.2), NEC 2023 (Articles 210.8, 250, 480, 690, 706, 710), Oregon Solar Installation Specialty Code (2010), NEC 690.12 Exception No. 2 (rapid shutdown exemption), NEC 690.7 Table 690.7(A) (temperature correction), NEC 690.8 (circuit sizing), NEC 690.45 / Table 250.122 (EGC sizing), NEC 250.53 (grounding electrodes), NREL PVWatts (production estimates), manufacturer published specifications (component data, listing certifications)