r/balconysolar commenters keep saying the same thing: new kit payback feels long, so they are pairing Craigslist panels with a new microinverter. That works. It also fails badly if you cheap out on the inverter or buy dead panels.
Here is the budget path I would actually follow in 2026.
Compare budget DIY cost vs all-in-one kit payback at your utility rate.
Run payback math →The budget formula
| Component | Buy used? | Typical cost |
|---|---|---|
| Panels (2× 400W) | Yes | $100–$200 local |
| Microinverter (new) | Never used | $150–$250 |
| Railing mount / frame | New or DIY | $50–$120 |
| Cabling, connectors | New | $30–$60 |
| GFCI outlet upgrade (if needed) | Electrician | $0–$150 |
| Total | $330–$780 |
The inverter is non-negotiable new with a current UL 1741 SB certificate. Used panels are fine if you test them.
Where to find used panels
Craigslist / Facebook Marketplace: Rooftop upgrade leftovers dominate. Look for 300–450W mono panels, ≤10 years old, no obvious cell cracks.
Solar installers: Some sell pulled panels after rooftop swaps. Call local installers and ask if they have “decommissioned but working” stock.
Avoid: Unknown-brand AliExpress panels with no spec sheet, panels with microcracks across cells, anything stored flat in a puddle for years.
Test before you mount
- Visual: No cracked cells, bent frames, corroded junction boxes
- Voc check: Multimeter on open circuit in sun. Should hit spec sheet Voc ±10%
- Match pairs: Two panels on one HMS-800 should be within ~5% wattage rating
Bad panels waste a good inverter. Spend 20 minutes in a parking lot before you haul them upstairs.
Pick the inverter (new only)
Hoymiles HMS-800-2T ($150–$250): two inputs, 800W AC, best for dual-panel builds. See microinverter comparison.
APsystems EZ1-LV ($140–$180): single 400W panel starters.
Buy from a US distributor (Signature Solar, Renvu) so warranty and UL docs are traceable.
Mounting on a budget
- Railing clamp kits: $40–$80 on Amazon; verify wind load for your floor height
- Freestanding A-frame: Lumber + concrete blocks if landlord bans railing mounts
- Fence-line: See fence-line mounting guide
Do not drill into building facade without written landlord approval.
Wiring and safety
- Panel DC → microinverter → NEMA 5-15 plug into GFCI outlet
- Dedicated 15A or 20A circuit preferred (NEC backfeeding)
- Keep cord off walking paths; strain-relief the plug connection
- Notify utility if your state law requires it
Anti-islanding is in the inverter firmware, not something you add later.
Payback example
Oregon buyer, PGE territory, ~13¢/kWh, 800W used-panel build for $550 total:
- Production: ~2.8 kWh/day average annual
- 70% self-use: 1.96 kWh/day × $0.13 = $0.25/day → $93/year
- Payback: 5.9 years
Same math at Maryland 21¢ retail: $150/year, payback 3.7 years.
Used panels are why Reddit skeptics say “payback isn’t that bad.” They are right if you skip the $1,900 battery bundle.
What not to do
- Used microinverters: No warranty, unknown firmware, possible failed anti-island
- No UL listing: Insurance and liability nightmare
- Power stations as grid tie: Jackery/Bluetti are not plug-in solar (power stations vs plug-in)
- Skip GFCI: Required for plug-connected loads outdoors
Document UL listing for your insurer before you plug in.
Plug-in solar insurance guide →Related: EcoFlow vs Hoymiles vs APsystems | Oregon & Washington Plug-In Solar | Best Balcony Solar Kits 2026
Dana Whitmore
Energy Engineer & Billing Analyst · Optiwatt Energy Advisor
Dana has spent the past three years analyzing residential electricity billing data across PG&E, SCE, and SDG&E service territories. She's reviewed billing records for thousands of California households, and built the simulation engine that powers this site's rate-plan comparisons. She holds a degree in Electrical Engineering and lives in the Bay Area.