For years, the cheapest way to wire a generator into a house has been an interlock kit — a metal plate on the panel that costs less than a nice dinner out. So it’s natural to assume the same trick carries over once solar panels and a battery arrive. It usually doesn’t, and the reason has little to do with price.
An interlock kit is a sliding bracket that physically blocks the main breaker and a generator breaker from being on at once, which is what stops a generator from backfeeding the grid. A transfer switch does the same safety job with a dedicated switching mechanism, often automatically.
Why the interlock trick caught on
It’s mostly cost. According to Consumer Reports, an interlock setup runs roughly $50 to $150 for the hardware plus an electrician’s labor, while a transfer switch typically lands between $500 and $1,500 installed. For someone with a portable generator they roll out a few times a winter, that gap is the entire argument.
What changes with a hybrid inverter
Solar and storage break the assumption. A grid-tied battery runs through a hybrid inverter that’s constantly monitoring the grid, detecting outages, and islanding the home on its own. Interlock kits are built around manual operation; they generally aren’t designed to coordinate with that kind of always-on equipment, and many simply aren’t compatible with it.
That’s why solar-plus-storage installs lean on switching designed for solar and storage instead. It can disconnect from the grid the instant it drops, decide which circuits get backed up, and fold in a generator later if you want one — none of it needing a person at the panel.
There are still cases where an interlock makes sense:
Portable generator only — no solar, no battery Someone is reliably home to run it Budget is the deciding factor, and outages are rare
What the owner actually feels
In practice, the difference shows up the moment the grid drops. With a battery and integrated switching, an outage is close to a non-event. A manual bracket means walking to the panel in the dark, cutting the main, and flipping breakers in the right sequence before anything comes back. Inspectors tend to read the two differently as well — a load hub that brings every source together reads as an asset, whereas a kit can raise questions. Whatever the hardware, one rule never bends: backup power must never flow back onto utility lines, which Consumer Reports and electricians alike flag as both illegal in most places and a real hazard to line crews.
Anyone planning a battery now — or leaving room for one later — is better off seeing how integrated switching ties solar, storage, and a generator together before settling on a bracket.
Источник: stroibloger.com