Show HN: My $1k self-install, off-grid solar backup build for renters
A renter-friendly, $1k off‑grid solar backup system that runs through extension cords and window-fed cabling is drawing strong interest as a way to cut high electricity bills and ride through increasingly common blackouts and safety shutoffs. Commenters highlight how cheap used commercial panels and modern LiFePO₄ batteries make small DIY systems economically attractive, even for EV charging or partial home backup. At the same time, many raise serious concerns about electrical code violations, fire risk, landlord approval, and insurance coverage, arguing that portable “solar generators” or properly permitted installations are safer alternatives.
Used / Decommissioned Panels and Performance
- Several commenters report buying used commercial panels very cheaply (e.g., SunPower T5) and say they still operate near original output.
- Explanation offered: commercial sites swap panels early to chase incentives, higher efficiency, and better land use, creating a cheap secondary market.
- Others ask for sources; specific surplus vendors and links are mentioned.
- Some uncertainty remains about performance beyond ~20 years.
Power Outages and Motivation for Backup
- Many report frequent or memorable outages in otherwise “first world” locations: rural U.S., Canada, parts of California, Pacific Northwest, Northeast U.S., Spain.
- Causes cited: ice storms, wind, trees on lines, wildfires, utility “public safety” shutoffs, aging infrastructure.
- Others say they rarely or never lose power and see backup as unnecessary except for edge cases.
- Several people frame DIY solar + batteries as a way to keep critical loads (heat, fridge, lights, comms) running during increasingly common grid disruptions.
Safety, Code Compliance, and Landlord Issues
- A large subthread argues the showcased setup is code‑breaking and dangerous:
- Bare or lightly protected DC wiring through windows.
- Rooftop panels not structurally secured or ballasted per code.
- Long extension‑cord “alternate circuits” treated as permanent wiring.
- Non‑listed or uncertified batteries/inverters indoors.
- Detailed NEC citations are provided to argue this would fail inspection in the U.S. and may violate rules in Canada.
- Others counter that:
- DC voltages and LFP chemistry are relatively safer than many think.
- Residents routinely use extension cords and portable systems.
- Insurance typically pays claims even when work isn’t to code, though non‑renewal is likely.
- Landlords in the thread generally say they would forbid such installs due to fire, liability, and roof‑damage risks, especially in rentals.
Economics, Payback, and Alternatives
- In very high‑price markets (e.g., parts of California) commenters see excellent payback; in low‑price regions (e.g., parts of the U.S. Southeast) payback can exceed a decade.
- Some stress that grid‑tied, permitted systems with or without net metering can be more economical than DIY off‑grid, depending on local tariffs.
- Alternatives suggested:
- “Solar generators” (portable battery + inverter + MPPT).
- Proper hybrid inverters that prioritize solar, then grid, then battery.
- Small backup batteries or generators sized only for critical loads.
- Using ice, extra thermal mass in freezers, or generators instead of large solar systems for rare multi‑day outages.
Aesthetics and Practicality
- Multiple people note the cabling is visually intrusive and would fail basic “acceptance factor” for partners or landlords.
- Some are inspired by the concept (cheap, renter‑friendly backup) but want a cleaner, code‑compliant, plug‑and‑play version.