There's a widespread assumption that a house with solar panels will keep the lights on when the grid goes down. For most systems, that's simply not true — and it's one of the first things a buyer should understand about a solar home, especially in hurricane, wildfire, and storm-prone regions. What a buyer actually inherits depends on whether there's a battery, how that battery is wired, and how much life and warranty it has left. Here's what to check.
Why solar alone goes dark in an outage
Almost all grid-tied solar systems are designed to shut off during a power outage. It's a safety feature: the system can't feed electricity back into lines that utility crews may be repairing. So unless the home has battery storage (or specific islanding hardware), the panels stop producing the moment the grid fails — exactly when a homeowner expects them to help. A buyer counting on solar for storm resilience needs to know this before closing.
What a battery actually changes
A battery with the right setup lets the home keep running critical loads when the grid is down. But "has a battery" isn't the whole story — three details determine what the buyer really gets:
- Whole-home vs. partial backup. Many installations back up only a subset of circuits (a "critical loads panel") — often fridge, some lights, and outlets, but not central air. Confirm what's actually on backup.
- Capacity and runtime. A single battery might run essentials for part of a day; multi-day outages need more storage or careful load management.
- Battery age and warranty. Batteries carry 10–15 year warranties and degrade over time. A battery halfway through its life has less usable capacity and fewer warranty years than the spec sheet suggests.
Storm-region specifics
In hurricane and wildfire areas, resilience is often the whole reason a system exists — so the details matter more. Worth verifying: whether panels and mounting meet local wind-load requirements, whether the battery is installed where heat or flood risk is managed, and whether the system has been inspected after any prior major storm. A buyer paying a premium for "storm-ready solar" should get confirmation, not marketing.
What to verify before you buy
- Is there a battery, and what's the make, model, and install date?
- Which circuits are backed up — whole home or critical loads only?
- Remaining battery warranty and current usable capacity.
- Does backup actually work? Ask when it was last tested.
- Who services the battery if the installer is gone? See our installer-out-of-business guide.
A SolarDisclosure™ report identifies the battery make, model, and warranty standing along with the rest of the system — so "storm-ready" is verified, not assumed.
Look up the system →Thinking about adding storage to a system that doesn't have it? See adding a battery to an existing solar system.
General information, not engineering or safety advice. Backup capability and storm ratings depend on the specific equipment and installation — verify with a licensed professional.