| Quick answer: A Public Safety Power Shutoff is a planned de-energization called by your utility when wind and fuel conditions make the lines a fire risk. Rooftop solar alone will not carry you through one — a grid-tied system is required to shut down when the grid goes away. Riding out a shutoff takes stored energy or a generator, plus equipment that safely isolates your house from the utility. |
The first time a household loses power for two days because of weather that never actually caused a fire, the reaction is usually the same: this cannot be how it works. It is how it works, it is deliberate, and it is likely to remain a feature of living in much of California. The question worth answering is not whether shutoffs will happen but what a house needs in order to be unbothered by one.
What a PSPS actually is, and who calls it
A Public Safety Power Shutoff is a temporary, intentional de-energization of specific circuits to reduce the risk of a wildfire started by electrical infrastructure. The decision belongs to the utility, not to the state or to your county. As the California Public Utilities Commission sets out on its Public Safety Power Shutoff pages, six investor-owned utilities hold that authority, and the standard is whether the utility reasonably believes there is an imminent and significant risk that strong winds could topple lines or drive vegetation into them.
The triggering conditions are a combination rather than a single threshold: sustained low humidity, forecast high winds and stronger gusts, dry fuel on the ground, and often a Red Flag Warning in effect. Utilities publish somewhat different criteria — PG&E states specific humidity and wind figures in its customer guidance, while SCE describes the same categories without publishing numbers — so it is worth reading your own utility’s page rather than assuming a statewide rule.
How long a shutoff lasts
Utilities are required to restore power within 24 hours of the end of the weather event, unless it is unsafe to do so, and to file an explanation with the CPUC if they miss that. That requirement is often misread as a promise that outages last a day. It is not. The clock starts when the wind event ends, not when your lights go out, and inspection of every de-energized line has to happen before re-energization.
In practice, most shutoffs are resolved within a few hours to a few days. A minority run considerably longer when a wind event persists or when damage is found during inspection. Plan for the range, not the average.
Why your solar shuts off too
This surprises nearly every solar owner during their first outage, and the explanation is a safety requirement rather than a defect. A grid-tied inverter must detect that the grid has gone away and stop energizing the lines within about two seconds. The behaviour is called anti-islanding, and the reason is that a line crew treating a circuit as dead must not have your inverter quietly back-feeding it.
In California this is not optional. Storage and generation connect under the CPUC’s Rule 21 interconnection tariff, and inverters interconnected to utility systems in the state must be certified to UL 1741 SB, which tests conformance to IEEE 1547-2018 — the standard that mandates the shutdown. The Department of Energy puts the consumer version plainly: solar systems are designed to switch off if grid power cuts out, and riding through an outage requires both a properly configured inverter and storage.
What backup actually requires
Three things have to be true. You need a source of energy that is not the grid. You need equipment that disconnects your house from the utility and forms its own stable island, which is what a battery’s backup gateway or a generator’s transfer switch does. And you need the loads you care about to be wired so that source can reach them — often through a dedicated backup panel rather than the whole house.
That last point causes the most disappointment. A battery sized for evening bill savings and wired to cover the whole main panel can be overwhelmed in an outage by loads nobody thought about. Deciding in advance what must stay on — refrigeration, well pump, medical equipment, a few circuits of lighting, internet, perhaps one air conditioning zone — is what makes a backup system behave the way people imagine it will.
Battery or generator?
| At a glance | Home battery | Standby generator |
| Runtime limit | Stored kWh, recharged by solar each day | Fuel supply, refillable indefinitely |
| Multi-day outage | Works if paired solar can recharge it daily | Works as long as fuel lasts |
| Everyday value | Also shifts usage out of the peak window | None — idle until an outage |
| Noise and emissions | Silent, no combustion | Audible, combustion by-products, ventilation required |
| Maintenance | Minimal | Routine servicing and fuel management |
| Heavy motor loads | Bounded by the unit’s surge rating | Generally strong, sized by generator capacity |
| Incentive eligibility | May qualify for storage programs | Generally not |
Neither is universally right. A remote property that regularly loses power for four days in winter has a strong generator case. A household in a shutoff-prone area that also has an expensive evening peak gets two benefits from one purchase with storage, because the battery earns its keep on the 361 days nothing goes wrong. Some households sensibly end up with both.
Will your panels recharge the battery during a shutoff?
Yes, if the system is configured for it — and this is the single most valuable feature during a multi-day event. Once the battery and its gateway have formed an island, correctly configured solar can charge the battery inside that island, so the house effectively runs on a daily solar cycle for as long as the outage lasts. Without storage the same panels sit idle in full sun, which is the detail people find hardest to accept.
Recharge is weather- and season-dependent, though. An October shutoff in smoke haze produces less than a clear June day, and a battery that comfortably covers an evening may not cover a full 24-hour cycle plus air conditioning.
Sizing for a shutoff, not for a bill
These are different design problems and they pull in different directions. Bill-shifting asks how much energy moves out of the 4 to 9 p.m. window. Resilience asks what has to run, at what power, for how many days, with what recharge. A system optimised purely for one may disappoint at the other, which is why the honest starting point is deciding which matters more to your household — or accepting a compromise deliberately rather than by accident.
Households with medical needs
If someone in the home relies on electrically powered medical equipment, this stops being a comfort question. California utilities operate Medical Baseline programs that provide an additional monthly energy allotment at the lowest price and, importantly, escalated PSPS notification — alerts well ahead of a shutoff, with in-person contact if they go unacknowledged. Some utilities also run portable battery or generator programmes for qualifying medically vulnerable customers in high fire-threat areas. Eligibility rules differ by utility and by year, so contact your utility directly rather than relying on a summary.
When to sort this out
Earlier than you think. Shutoff events in California are not confined to a narrow season — the CPUC’s own event records show them running from early summer through late autumn, with heavy clustering in October through December driven by offshore wind events, and Southern California events extending into January. Meanwhile a battery installation involves permitting and utility interconnection under Rule 21, which takes time. Starting in the week the wind picks up is starting too late.
Solari sizes systems to a household’s actual bill and backup priorities, identifies which programs a property qualifies for, and project-manages the permits and interconnection; the physical installation is carried out by a licensed contractor. Send a recent utility bill and a short list of what must stay on during an outage, and you will get a straight answer — including if the answer is that it does not make sense for your house. You can start with a bill review, and the home battery FAQ covers the common follow-ups.
Frequently asked questions
How much notice do I get before a PSPS?
Utilities aim to notify roughly 48 and 24 hours ahead, again in the hours immediately before, and then daily until restoration. Fast-moving weather can compress that, so notifications are not guaranteed.
Can I run my whole house on a battery during a shutoff?
Sometimes, but it depends on the system’s power rating, its stored capacity and your actual loads. Most households get a better result by backing up a defined set of essential circuits.
Does a battery keep working if the outage lasts several days?
It can, provided paired solar is configured to recharge it inside the island and daily generation covers daily use. Without recharge, a battery runs until its stored energy is gone.
Is a battery safe to have on the house during fire season?
Home battery systems sold in the United States are certified to recognised safety standards and permitted through your local building department, and California requires their inverters to be certified under Rule 21. Placement and clearances are governed by local code, which your permitting authority and installing contractor will apply.
How do I find out what my house needs?
Send a recent utility bill and a list of what has to stay on during an outage to Solari, and you will get a straight read with no obligation and no sales call unless you ask. Reach Solari at (916) 507-1626 or stephen@solaristorage.com. Coverage is California only.
Key takeaways
- A PSPS is called by your utility, and restoration is required within 24 hours of the weather event ending — not within 24 hours of your outage starting.
- Grid-tied solar shuts down in an outage because anti-islanding is a safety requirement under Rule 21 and UL 1741 SB; storage is what lets it keep working.
- Sizing for resilience is a different exercise from sizing for bill savings, and deciding which matters more comes before choosing hardware.
- Send a recent utility bill and your must-stay-on list to Solari — (916) 507-1626 or stephen@solaristorage.com.
