The short answer
If your home goes dark during a grid outage, the useful first question is whether the installed system was designed to supply backup power. If it was, identify what stopped: every backed-up circuit, one appliance, solar charging, or power after several hours. Those observations lead to different service requests. A sunny roof and a battery display are not enough to diagnose the interruption.
Grid-connected solar generally shuts down when utility power fails unless an approved backup arrangement allows it to operate independently. DOE describes this safety distinction in its solar resilience guidance. There are equipment-specific exceptions to battery-based backup: Enphase's documented Sunlight Backup configuration supplies selected essential loads in daylight without a battery. That capability requires a complete supported configuration, not merely an IQ8 model name. Enphase Sunlight Backup
This guide concerns U.S. installed residential systems. It helps you choose a capability review, a load review, or fault service. It does not provide a shutdown sequence or a way to connect a generator. During smoke, arcing, a burning odor, flooding around electrical equipment, or loose storm-damaged components, move away and seek emergency or qualified electrical help. Do not approach equipment to collect better data. DOE warns that untrained people must not touch PV electrical components even when they are presumed de-energized. DOE PV safety guidance
Branch one: the installation has no documented backup mode
Look in the commissioning report or owner's documentation for the operating configuration. Ask the service provider to confirm whether it is grid-connected solar only, battery storage without backup, partial-home backup, whole-home backup, or a specific daytime-only arrangement. Do not infer the answer from a product brochure describing capabilities your installation may not include.
If the paperwork says solar only and support confirms no backup arrangement, loss of household power during an outage may match the design. An emergency inverter replacement would not be justified by that observation alone. Ask the provider to explain how normal production resumes after utility restoration and whether any current event indicates a separate fault.
If backup matters to you, request a separate feasibility review after the outage. Name the loads you need and the conditions you want covered, such as overnight refrigeration or a well pump during cloudy weather. Ask what equipment, electrical work, controls, local approvals, and utility review would be required. This is a design decision; adding a battery or buying a larger inverter should not be assumed to deliver the intended result.
If your purchase documents promised backup but the commissioning record does not show it, ask the installer to reconcile the discrepancy in writing. Keep the installed-capability question separate from any contract remedy. For ownership and purchase-record questions, see the solar-home ownership and backup checks.
Branch two: some circuits work and others do not
Use the existing circuit schedule, rather than experimenting with breakers. Note which ordinary lights or appliances were already operating and which lost power. Compare them with the provider's list of backed-up circuits.
If the refrigerator works but an unbacked-up range does not, that observation may fit a partial-backup design. If a circuit listed for backup stays unavailable, tell support its label, the affected appliance, the outage time, and the current app status. A failed appliance and an unavailable circuit are different complaints; avoid opening equipment to distinguish them yourself.
Ask the provider whether intentional load control is involved. Enphase's Sunlight Backup guide describes controlled loads and states that off-grid supply can shut down when available solar power cannot meet the loads. Cloud cover can therefore matter even while it remains daytime. That is a configuration-specific operating limit, not proof that every daytime interruption is normal. Enphase homeowner guide
Your service decision changes when a previously supported essential circuit is now consistently unavailable, the app reports a fault, or the written load schedule does not match observed behavior. Request a review of that circuit's backup assignment and control status before paying for additional battery capacity.
Branch three: power stops when a demanding appliance starts
Write down the sequence using events you already observed: which appliance started, whether all backup power stopped, what the app reported, and whether service returned. Do not repeatedly start the appliance to reproduce the problem.
Power and stored energy answer different questions. Kilowatts describe power at a moment; kilowatt-hours describe energy over time. A battery with energy remaining can still face a power constraint. EIA explains the units; the installer must assess the equipment's actual continuous and short-duration capability and the household load requirements. EIA measuring electricity
Tesla's Powerwall outage guidance specifically identifies overload from starting energy-intensive loads as a reason backup supply can stop. This is a useful example of why a remaining-charge display does not clear the load question. Use the instructions for your own system rather than transferring Tesla's restart procedure to another brand. Tesla outage practices
Request a load assessment when the interruption repeatedly follows normal use of an appliance the installation was meant to support. The report should address the appliance's starting requirement, simultaneous loads, installed power limits, and any approved control strategy. A quote for another battery should explain which constraint it resolves and whether other components or controls also limit the result.
Branch four: backup lasts for a while, then stops
Save the state-of-charge information available before and after the interruption, the duration already observed, the solar and household-energy screens, and any full event message. Ask support whether the system reports depletion, a protective standby state, an overload, or another fault. There is no universal remaining-charge percentage or recovery sequence for all home batteries.
If the provider identifies depletion, review what consumed energy and what solar recharge actually occurred. Ask for an estimate based on the installed usable energy, reserve behavior, expected loads, and stated weather assumptions. Treat the estimate as conditional. Do not infer overnight duration from the array's nameplate watts or from one short demonstration.
If power disappeared soon after transition despite adequate reported charge and modest intended loads, request fault investigation rather than accepting “you need more storage” without supporting findings. The technician should state whether the charge value was current and what event evidence supports the diagnosis.
Branch five: the home has backup power but solar production pauses
A solar pause while the home remains powered can be a different operating condition from failed backup. Tesla explains that Powerwall may signal solar to reduce or stop when production exceeds what the home can use and the battery can store, then allow it again when storage can accept energy. That explanation applies to the described Powerwall arrangement. Tesla outage practices
Give support simultaneous solar, battery, load, and grid-status readings if they are safely available. Ask whether the pause matches documented control behavior. A full battery, paused solar, and powered essential loads should not automatically generate the same repair scope as an empty battery and a dark backup panel.
Buy the assessment that matches the branch
A useful written scope identifies the installed backup configuration, the observed interruption, and the question to be answered. Ask who will review controller events, load assignments, power limits, charge history, and transition behavior. Electrical testing and a controlled demonstration belong with qualified personnel under a site-specific procedure.
Separate diagnostic fees from optional upgrades. Before authorizing equipment, require the proposed model, the constraint it addresses, compatibility evidence, applicable local and utility approvals, and a commissioning plan. An upgrade promise should state which appliances it supports, simultaneous-use limits, and which weather or duration assumptions remain.
Close the service request with an explanation tied to your actual branch. For a corrected fault, keep the event findings and professional completion tests. For an operating limit, obtain a revised load plan and a clear trigger for calling again. For missing capability, retain the documented feasibility outcome. Keep those records with your solar and battery maintenance file so the next outage starts with a known operating plan.