NEC codes for solar and energy systems — a plain English guide
NEC 551 — Recreational Vehicles
Covers electrical systems in RVs, including solar installations on motorhomes, travel trailers, and van conversions. If you’ve wired or are planning to wire solar on your RV or van, this is your section — it sets rules for wiring methods, grounding, battery compartments, and how solar integrates with the vehicle’s existing electrical system.
Applies to: RV and van solar installers.
Cross-links: RV Solar Panel Wiring · Van Life Solar Setup · Off-Grid RV Solar · RV Battery Bank
NEC 690 — Solar Photovoltaic Systems
The primary code governing residential and commercial solar panel installations. It covers everything from panel placement and wiring to how your system disconnects from the grid during an outage and how it must be labeled. Plug-in balcony systems fall under a subset of this code, and hardware must meet UL 3700 certification to be considered safe for reverse-current feed into your home’s wiring.
Applies to: All grid-tied and off-grid solar panel installs.
Cross-links: Plug-and-Play Solar · Balcony Solar · Beginner’s Solar Kits
NEC 705 — Grid Interconnection
Covers how your solar or battery system ties into the utility grid — including the size limits on systems that can connect without utility approval, the required grid-protection devices, and how power flows between your home, your batteries, and the grid. If you’re considering a home battery backup that can export to the grid, or a hybrid inverter, this is the section that governs what your installer has to do. For the full breakdown — load-side vs. supply-side connections, the 120% rule, and the AHJ sign-off process — see NEC Article 705 in Plain English.
Applies to: Grid-tied solar and battery systems.
Cross-links: Home Solar Power Banks · Solar Generator as Home Backup
NEC 706 — Energy Storage Systems
Governs battery systems — from individual lithium cells to whole-home battery banks. It covers installation, spacing, temperature limits, disconnect requirements, and how storage systems interact with both solar panels and the grid. Covers LiFePO4, lead-acid, and other chemistries. Also relevant to EV charging setups that draw from or buffer power in battery systems.
Applies to: All solar battery installations, off-grid storage, backup power systems.
Cross-links: LiFePO4 Batteries · RV Battery Bank · JuiceIndex — EV charging stop planning
NEC 750 — Energy Management Systems and Alternative Generation
Covers systems that manage multiple energy sources — including solar, wind, fuel cells, energy storage, and EV charging — under a single controls framework. If your home coordinates solar panels, a battery, an EV charger, and demand response signals from your utility, that coordination falls under NEC 750. It’s the newest and least-well-known of the bunch, and it’s increasingly relevant as homes add EVs and smart energy management.
Applies to: Homes with multiple energy sources, EV chargers, smart demand-response systems.
Cross-links: JuiceIndex — EV charging stop planning · Solar Generator Kit