Stand-Alone Systems

Article 710 gathers the requirements for stand-alone (off-grid) power systems in one place. These are premises supplied only by their own generation and storage — remote cabins, rural homes, telecom huts, anywhere the utility simply isn't. It grew out of scattered provisions in the solar and interconnection articles as fully off-grid installs became common.

Key points: the supply output must be able to handle the largest single load that could start, plus rules on sizing the inverter to the calculated load, allowing an inverter output rating in place of a conventional service calculation. It addresses back-fed and multi-source arrangements, disconnects, and the fact that an off-grid inverter can be the sole source — so its overcurrent behavior and grounding matter more than usual. It reads as the off-grid companion to Article 705's grid-tied focus.

When it applies

Article 710 covers stand-alone systems, installations that power a structure entirely without a permanent utility connection. Think a remote cabin or off-grid property running on PV, batteries, and maybe a generator, where your sources have to carry the whole load on their own.

Common mistakes

• Sizing the inverter output circuit below the largest single load the system must actually start and run.
• Forgetting that with no utility backing you up, source and storage capacity has to be planned for real peak demand, not average.
• Neglecting a clear means to shut down and service the power source safely.

In the field

On an off-grid cabin I had to remind the owner there is no grid to lean on when the well pump and the fridge both kick on at once. The inverter and battery bank have to swing that combined surge alone. I sized the output circuit to the largest load the system supplies and built in headroom for simultaneous starts. Stand-alone means your design is the only safety net; there is no utility to cover a shortfall.