Grid failure response

Infrastructure fails in sequence, not all at once

A standard power outage from a storm or equipment failure is usually localized and repaired within hours to days. A geomagnetic storm severe enough to damage high-voltage transformers at multiple points in the grid operates differently. NOAA's Space Weather Prediction Center documents historical events in which geomagnetic storms caused transformer saturation, overheating, and failure across large regions. The 1989 storm blacked out the entire Quebec province for nine hours and damaged transformers that took months to replace.

Large power transformers are custom-built and not stocked in large numbers. When multiple transformers fail across a wide area simultaneously, the repair timeline is measured in weeks, not days. Ready.gov's space-weather guidance reflects this: it treats severe geomagnetic events as long-duration outages, not standard outages.

The cascade effect matters. When electricity goes, water treatment and pumping stations lose power within hours. Municipal water pressure drops as storage tanks drain without replenishment. Fuel pumps at gas stations stop working. Cell towers run on battery backup for a few hours before going offline. The outage is not just darkness. It is water, fuel, and communications in sequence.

Water before everything else

Ready.gov's space-weather preparedness guidance is explicit: fill bathtubs, sinks, and every available container with water while municipal pressure still holds. This is the single most time-sensitive action in the first hour of a major grid failure. Once pressure drops, municipal water is gone until the grid comes back.

A standard bathtub holds 30 to 50 gallons. With two people and a 3-day minimum of one gallon per person per day, that is 6 gallons needed just for drinking and cooking. The rest of the stored water covers sanitation. Fill everything available immediately, before doing anything else.

After water: note how much food is in the house and plan around refrigerator and freezer contents first. A full freezer maintains temperature for about 48 hours if left closed. A half-full freezer for about 24 hours. Eat from the refrigerator first, then the freezer, then shelf-stable supplies.

Locate a battery-powered or hand-crank NOAA radio. Cell phones will have limited battery and no signal as towers go offline. The NOAA radio is the most reliable way to receive emergency broadcast information when the broader communications infrastructure is degraded.

Foil wrapping, generator runs, and driving for supplies

Wrapping electronics in aluminum foil after a geomagnetic event has already damaged the grid provides no protection. A Faraday cage only protects unpowered electronics from an EMP if they are shielded before the pulse arrives. Retroactive foiling is not a useful action. The concern about electronics is legitimate for future preparedness planning, but not as a first-hour response.

Running a generator immediately is tempting but comes with risks that outweigh the benefits in the first hour. Generators should never run indoors or in attached garages: carbon monoxide kills quickly and silently. In the first hour, the priority is water, not power. If a generator is available and can be used safely outdoors, it becomes valuable in hour two and beyond for running a sump pump, a medical device, or refrigeration.

Driving immediately to buy supplies contributes to road congestion at exactly the moment emergency responders need clear routes. If supplies are genuinely missing and stores are open, a quick targeted trip is reasonable. A broad supply run to multiple stores in the first hour is usually counterproductive and expends fuel that becomes critical if the outage lasts more than a few days.

The 50% rule for lead-acid deep-cycle batteries

Lead-acid deep-cycle batteries — including AGM and flooded types — suffer permanent capacity loss when regularly discharged below 50% of their rated capacity. This threshold, known as depth of discharge (DoD), is a key maintenance principle. On an overcast day, a 100-watt solar panel may produce only 10 to 20 watts — insufficient to recover a deeply discharged battery. The protective action during a prolonged low-production period is to reduce loads rather than drain the battery further, preserving both current charge and long-term capacity. Lithium iron phosphate (LiFePO4) batteries tolerate deeper discharge and are less sensitive to this issue.

Why grid-tied solar stops when the grid does

Grid-tied solar inverters include anti-islanding protection that automatically disconnects the system when grid power fails. This is a deliberate safety feature to prevent the system from backfeeding electricity onto power lines where utility workers may be present. It is not damage from a storm or geomagnetic event — it is designed behavior. An off-grid or hybrid system with a dedicated battery bank and off-grid inverter operates independently of the grid. This distinction matters for anyone evaluating solar as an emergency backup power source: grid-tied without battery storage provides zero outage benefit.