Battery & storage
Enter a conservation-mode load, expected shutoff length, and strong clear-day solar offset. Get a battery size for a planned safety power shutoff.
How it works
Step 1
A multi-day planned shutoff benefits from the same conservation approach as any extended outage, similar to the storm season planning tool.
Step 2
PSPS events happen on clear, dry, high fire-risk days, meaning excellent solar production is typical, not the exception.
Step 3
Utilities typically warn a day or more ahead, giving time to top off the battery before the shutoff begins using the charge time from grid tool.
A Public Safety Power Shutoff, or PSPS, is a planned, preemptive outage that a utility initiates during high fire-risk weather conditions, typically hot, dry, and windy weather, to reduce the chance of a wildfire igniting from power line contact with vegetation or equipment failure, a wildfire-prevention practice Ready.gov's power outage preparedness guidance also addresses as part of planning for planned outages specifically. Unlike a storm outage, which often strikes with cloud cover and limited warning, PSPS events happen on clear days with excellent solar production, both factors this calculator accounts for differently than the storm season backup planning tool.
The same hot, dry, clear weather conditions that raise wildfire risk also happen to be excellent conditions for solar panel output, since clear skies without cloud cover allow panels to operate near their rated capacity throughout the day, consistent with NREL's solar resource data. This means a household's solar system often produces close to its best daily output during precisely the conditions that trigger a PSPS event, meaningfully reducing the net battery capacity needed compared to a cloudy storm scenario with the same conservation-mode load.
Utilities in wildfire-prone areas typically issue PSPS warnings anywhere from several hours to a day or more before the actual shutoff begins, based on forecasted fire-weather conditions. This advance notice gives households a genuine opportunity to fully charge their battery using the charge time from grid tool before the shutoff starts, unlike a storm that can knock out power with little to no warning, and confirming your inverter can complete this rapid charge in time is covered by the hybrid inverter sizing calculator in our Inverters & Equipment category.
If you're in a region that experiences both storm outages and PSPS events, comparing this result against the battery reserve percentage tool shows how differently these two scenarios affect your realistic battery needs. If financing affects your PSPS-readiness budget, the quick financing comparison tool in our Financing category gives a fast cost overview.
Questions
A household running a 500 watt conservation load for 3 days, with strong 6 kWh daily solar offset typical of clear fire-weather conditions, needs about 22 kWh of nameplate capacity, roughly 2 batteries, since PSPS events usually coincide with excellent solar production.
A Public Safety Power Shutoff, or PSPS, is a planned, preemptive outage a utility initiates during high fire-risk weather conditions, typically hot, dry, and windy, to reduce wildfire ignition risk from power lines. Unlike storm outages, PSPS events happen on clear days with strong solar production, and utilities usually provide advance notice.
Yes, utilities typically issue PSPS warnings a day or more ahead of the shutoff, which gives time to fully charge the battery from the grid or maximize solar charging before the outage begins, unlike a storm that may knock out power with little warning.
PSPS event duration varies by utility and weather conditions, but many last from several hours up to 2 to 3 days, though some extended high-risk periods have lasted longer. Checking your specific utility's PSPS history for your area gives a more precise planning figure.