Okay, let's break down NEC 690.13 in the context of a hybrid inverter with DC PV, DC battery, AC grid, and AC load connections.

Understanding the Goal of 690.13

The core intent of 690.13 is safety. It's about providing readily accessible and reliable means to completely de-energize the PV system (or critical parts of it) for maintenance, emergencies (firefighting, rescue), or other operational needs. This ensures that personnel can safely work on any part of the electrical system without being exposed to dangerous voltages and currents from the PV array.

Applying 690.13 to a Hybrid Inverter Setup

Let's analyze each connection point and what's required:1. DC PV Connection

Definitely requires a disconnect. This is the primary source of PV-generated power. A disconnect must be installed between the PV array and the inverter. This disconnect needs to be appropriately rated for the DC voltage and current from the PV array. The common term is "PV Disconnect" and it's often a large, lockable DC-rated switch.2.

DC Battery Connection

Requires a disconnect. While not part of the PV system itself, the energy storage system is included in 690.13. Batteries can supply power back into the inverter (and potentially to other circuits), so a disconnect is needed to isolate the battery bank. This disconnect should also be appropriately rated for the DC voltage and current of the battery system. It's also important for safety during battery maintenance or replacement.
3.

AC Grid Connection

Requires a disconnect. This is your connection to the utility grid. A disconnect is necessary to isolate the inverter from the grid. This is typically accomplished with an AC disconnect.4.

AC Load Connection

Requires a disconnect. Even if the load is normally supplied by the inverter, a disconnect is needed. This is because the inverter could backfeed the load circuit even if the grid is down (assuming it's configured to do so and has available power from PV or batteries). The disconnect ensures that the load wiring can be safely de-energized.

Important Considerations



Location

The location of the disconnects is critical. They must be readily accessible and located in accordance with other NEC requirements (e.g., within sight of the equipment, grouped together where possible, etc.). Check your local AHJ's specific interpretation of "readily accessible."

Listing

All disconnects must be listed for their intended use. This is especially important for DC disconnects, which have specific voltage and current interrupting requirements.

Lockout/Tagout

All disconnects should be capable of being locked in the open (off) position to prevent accidental re-energization during maintenance (lockout/tagout procedures).

MID (Maintenance Isolation Device)

While some hybrid inverters have built-in MID features, they do not always satisfy all the disconnection requirements of 690.13 on their own.

Your Related Question: Hybrid Inverter as Part of the "PV System"

This is a great question! With PV Disconnect Open

Technically, no, the inverter is not part of the PV system when the DC disconnect between the panels and the inverter is open. The inverter is then operating (potentially) as an ESS inverter. Its primary function is no longer processing power directly from the PV array. However, from a practical perspective, you still need to consider the inverter's potential to be energized from the battery and/or the AC grid. That's why the battery and AC disconnects are crucial, even if the PV disconnect is open.

In summary:

You generally need at least* four disconnects in your hybrid inverter setup to fully comply with 690.13:1. DC PV disconnect (between panels and inverter)2. DC Battery disconnect (between battery bank and inverter)3. AC Grid disconnect (between inverter and utility)4. AC Load disconnect (between inverter and critical loads)Always consult with a qualified electrical professional and your local Authority Having Jurisdiction (AHJ) to ensure your PV system installation meets all applicable codes and regulations. The AHJ's interpretation of the NEC can sometimes vary, so it's always best to get their approval during the design phase. Flag for review