Every disconnect in a solar system exists so that somebody other than you can make it safe — a firefighter at 3am, an electrician who has never seen your install, a utility worker. That framing explains the requirements that otherwise look fussy: they are about being findable, reachable and obvious under pressure.
The disconnects a typical system needs
| Disconnect | Separates | Typical location |
|---|---|---|
| DC disconnect | Array from inverter | At or beside the inverter |
| AC disconnect | Inverter from the panel | Beside the inverter or at the service |
| Utility-accessible disconnect | System from the grid | Outside, near the meter |
| Battery disconnect | Battery from everything | At the battery, close to the terminal |
| Rapid shutdown initiator | Roof conductors | At the service entrance |
Not every system needs all of these, and requirements vary by code edition and by utility. The utility-accessible outdoor disconnect in particular is a utility requirement more often than a code one — ask yours early, because retrofitting it means opening finished work.
Placement is what gets checked
Inspectors check that disconnects are readily accessible — reachable without a ladder, without moving obstructions, and without opening another enclosure. A DC disconnect tucked behind the inverter where nobody can reach it in an emergency fails inspection even though it is electrically correct.
They must also be labelled to identify what they isolate, and marked to indicate on and off positions. Labelling is the most commonly failed inspection item across DIY solar generally, and it costs stickers and a label maker to get right.
The DC arc problem, again
A DC disconnect is not a light switch with a bigger badge. Because DC does not cross zero volts, an arc drawn when contacts separate can sustain itself — so DC disconnects are built with specific arc-quenching mechanisms and are rated for a maximum DC voltage.
Two consequences. First, use a device rated for DC at or above your string voltage; an AC-rated switch is not a substitute. Second, and more practically: never break a DC connection under load. Open the disconnect properly, or shut down the inverter first so no current is flowing. Pulling an MC4 connector apart on a producing array draws exactly the arc the disconnect was designed to handle.
Rapid shutdown
Recent NEC editions require module-level rapid shutdown on rooftop arrays, so that conductors on the roof can be de-energised from a control at the service entrance. In practice this means microinverters, DC optimisers or dedicated module-level shutdown devices — a plain string inverter with none of those will not pass inspection under those editions.
This is an equipment decision, not something you add at the end. Establish which code edition your jurisdiction enforces before choosing your inverter, as covered in string versus microinverter.
The shutdown sequence, in order
- AC disconnect first — stop the inverter exporting
- Then the DC disconnect — isolate the array
- Then the battery disconnect, if one is present
- Then verify with a meter that everything you are about to touch is actually dead
And remember what a disconnect cannot do: the panels themselves are still producing voltage whenever light hits them. There is no switch on a solar module. Isolation stops power flowing downstream; it does not make the array inert.
Local amendments vary considerably here, so confirm with your building department rather than any general guide — including this one. The full inspection picture is in what inspectors check.