How to prepare your solar panels for a power outage or grid disruption

A lot of Hawaii homeowners assume that having solar panels means they will have power no matter what happens to the grid. That assumption causes real disappointment during an outage. Whether your system keeps the lights on depends entirely on how it is configured, and there are concrete steps you can take beforehand to make sure it performs the way you expect when it matters.

Why solar panels alone don’t solve an outage

Solar panels convert sunlight into electricity. They do not store it. Without a battery, any electricity your panels produce during the day has to be used immediately or sent to the grid; none of it is available after dark or during a grid shutdown unless a battery is part of the system.

That distinction explains the most common source of confusion: “I have solar panels, why is my power out?” The answer usually comes down to system type.

The three system types, and what each one does in an outage

Off-grid systems

Off-grid systems operate independently of the utility grid entirely. With a battery, they can keep providing power indefinitely as long as the sun (or another renewable source) keeps recharging the battery. Without a battery, an off-grid system has no power available whenever the sun isn’t generating.

Grid-tied systems

Most Hawaii solar systems installed without a battery are grid-tied. These systems are designed to shut down automatically the moment the grid loses power, for safety reasons, so utility crews working on downed lines are not at risk from your system feeding power back. If you have a grid-tied system with no battery, an outage means no electricity, solar panels or not.

Hybrid systems

Hybrid systems combine grid connection with battery backup. They draw from the grid when it’s available and switch to stored battery power when it isn’t, giving you continuous power through an outage while still using the grid normally the rest of the time. This is the setup we recommend for most Hawaii homeowners who want real outage protection; our solar batteries page covers the equipment options in more detail.

What to do before a storm or planned outage

Activate storm mode

Both Tesla and Enphase offer a storm-watch feature (Storm Watch for Tesla, Storm Guard for Enphase) that automatically switches your battery to full backup reserve when severe weather is forecast. It pulls alerts from national weather services, so your system starts preparing before the outage even hits. Keep in mind storm mode typically won’t trigger for planned or rolling outages, since there’s no weather event to detect.

Raise your battery reserve manually for known outages

For planned outages that storm mode won’t catch, raise your battery’s reserve setting. Most systems run a 20 to 30% reserve day to day; for a known outage, we recommend bumping that up to around 50% so you have a deeper cushion of backup power available.

Charge everything before the outage starts

If you get advance notice of a storm or planned outage, make sure your battery is fully charged and, if you have an EV, that it’s charged too. Cutting other non-essential loads in the hours before an outage also helps stretch what’s stored.

Managing your battery during the outage itself

Monitor your charge level

Don’t let a battery run itself down without checking in. Enphase recommends disconnecting backup loads around 10% charge, with full shutdown around 2%, and restarting only once a charging source (typically sunlight) is available again. Tesla Powerwall enters standby mode below 10% charge and sends an app notification; while in standby, it attempts hourly solar recharge checks and waits if the charge drops more than 2.5% between attempts.

Prioritize essential appliances

Not everything in your home needs to stay on during an outage. Refrigeration, medical equipment, lighting, and communications should take priority over things like electric dryers or pool pumps. Knowing which circuits are on your backup panel ahead of time, rather than figuring it out mid-outage, makes this much easier.

Avoid restarting a low battery mid-storm

Cycling a nearly depleted battery on and off during a storm shortens the window before it fully depletes. Let it complete a full recharge cycle when sunlight or grid power returns rather than repeatedly drawing it down and restarting.

After the storm passes

Once the outage ends, check your monitoring app to confirm production has returned to normal levels compared with pre-storm output. A storm can occasionally shift panel alignment, introduce debris, or trip an inverter fault that isn’t obvious without checking the numbers. If anything looks off, that’s the time to schedule a system check rather than waiting for the next bill to reveal a problem. Our service team can walk through your monitoring data with you if you’re not sure what you’re looking at.

Outage protection is a design decision, not an accident

The single biggest factor in how your solar system behaves during an outage is decided at installation: whether a battery is part of the design at all, and how the backup circuits are wired. If your current grid-tied system leaves you without power every time Hawaiian Electric loses a line, adding a battery retrofits that protection in. Our guide to Hawaii power outages covers what typical outage durations look like across the islands and what size battery actually covers a full day without sun.

If you’re not sure what your current system will do in the next outage, contact us for a system review, or get a free estimate on adding battery backup.