Santa Ana Winds and Power Shutoffs: How Solar Plus a Battery Keeps a San Diego Home Running During a PSPS

When SDG&E shuts off lines during fire weather, the outage is planned, announced ahead of time, and can last for days. That makes it the kind of outage a home battery handles best, as long as the system is ready before the wind arrives.

Key takeaways

• A Public Safety Power Shutoff is a planned outage: SDG&E turns off lines during fire weather so damaged equipment can’t spark a wildfire.
• Santa Ana season typically runs September through December, but shutoffs don’t always follow the calendar. Both of SDG&E’s 2025 events came in January.
• SDG&E’s notices usually start about 48 hours ahead, and a shutoff can last from several hours to multiple days.
• Solar panels without a battery go dark with the grid. A battery with a backup switch keeps the home running, and the panels recharge it every sunny day.
• Size backup around your essentials and set it up before fire season, not during a shutoff watch.

Frequently asked questions

What is an SDG&E Public Safety Power Shutoff?

A Public Safety Power Shutoff (PSPS) is a preventive outage. When wind, temperature, humidity, dry vegetation and input from fire agencies point to a high wildfire risk, SDG&E turns off specific circuits until the weather passes and crews can inspect the lines.

How much notice does SDG&E give before a power shutoff?

SDG&E’s customer notices typically start about 48 hours before a possible shutoff, followed by a confirmation a few hours before power is turned off. Alerts go out by phone call, text and email, and through the Alerts by SDG&E app.

How long does a PSPS last?

Anywhere from several hours to multiple days. Crews have to inspect every de-energized line in daylight before power comes back, and SDG&E’s January 2025 event ran from January 7 to January 16.

Will my solar panels work during a power shutoff?

Not without a battery. Grid-tied solar inverters are required to shut down when the grid goes down, so the house goes dark even on a sunny day. A battery with a backup switch disconnects your home from the grid, so the solar can keep running and recharging the battery.

How many Powerwalls do I need for a multi-day shutoff?

It depends on what you need running. Each Powerwall 3 stores 13.5 kWh. If your essentials use about 10 kWh a day, one Powerwall 3 can carry the evening and overnight, and a sunny day can refill much of what you used. Central air, pool pumps and EV charging raise the requirement quickly.

---

Most power outages are accidents. A Public Safety Power Shutoff is a decision. When fire weather builds in the backcountry, SDG&E can de-energize power lines on purpose so that a damaged line can’t spark a wildfire. For the homes on those circuits, the result is the same as any outage: no lights, no refrigerator, no Wi-Fi, no well pump. The difference is that you usually see it coming, and it often lasts longer than a typical outage.

That combination, advance warning plus long duration, is exactly where solar plus a battery earns its keep.

What a Public Safety Power Shutoff is

A PSPS is a preventive outage. According to SDG&E, the decision weighs wind speed and direction, temperature and humidity, how dry the vegetation is, field observations and input from fire agencies. When those conditions line up in high-risk areas, the utility turns off specific circuits until the weather passes and crews can inspect the lines.

You can see active and potential shutoffs on SDG&E’s PSPS dashboard, and SDG&E explains how decisions are made on its PSPS information page.

Why fall is shutoff season in San Diego

SDG&E describes Santa Ana wind season as typically running from September through December. Those hot, dry, offshore winds push down through the canyons of inland San Diego County, and they are the main reason shutoffs happen. They don’t always follow the calendar: both of SDG&E’s 2025 shutoff events came in January. And in early October 2026, SDG&E warned that nearly 35,000 customers, including parts of Poway and Ramona, could see their power shut off as fire weather moved in.

If your home sits in or near the inland foothills, plan for at least one shutoff watch each fall and winter.

How much warning you get

SDG&E monitors conditions days ahead. Its customer notices typically start about 48 hours before a possible shutoff, followed by a confirmation a few hours before power is turned off, updates during the event, and a notice when power is restored. Alerts go out by phone call, text and email, and through the Alerts by SDG&E app.

That lead time matters. Two days is enough to top off a battery, check which circuits are backed up and move the things you care about onto them.

How long a shutoff lasts

This is the part people underestimate. SDG&E says a PSPS can last from several hours to multiple days. Even after the wind dies down, crews have to patrol and inspect every de-energized line before power comes back, and SDG&E notes that inspection takes daylight, typically four to eight hours of it.

The January 2025 event shows the range: SDG&E’s own post-event report covers a shutoff that ran from January 7 to January 16 and affected more than 15,000 customers at various points. A plan that only covers one evening isn’t a plan for a PSPS.

Why solar panels alone go dark

If you already have solar, you might assume you’re covered. You’re not, unless you also have a battery. Grid-tied solar inverters are required to shut down when the grid goes down, so they don’t push power onto lines that crews are working on. On a bright, windy October afternoon, your panels will be producing and your house will still be dark.

What a Powerwall 3 does during a shutoff

A battery with a backup switch changes the picture. When the grid drops, a Tesla Backup Switch automatically disconnects your home from SDG&E’s lines. Your home becomes its own small, isolated system, and the Powerwall takes over.

• Storage: each Powerwall 3 stores 13.5 kWh.
• Power: it can deliver up to 11.5 kW continuously, enough to run most household loads at once.
• Solar recharge: the Powerwall 3 has a built-in solar inverter, so your panels keep charging the battery during the day while the grid is off. That’s what turns a one-night battery into a multi-day one.
• Storm Watch: once enabled in the Tesla app, Tesla’s Storm Watch charges the battery to full when alerts such as red flag or high wind warnings are issued for your area.

Sizing for a multi-day shutoff

Start with what you need to keep running, not with how many batteries you can fit in the garage. That’s the first question in any home battery backup plan in San Diego, and it decides everything else about the installation. A typical essentials list looks like this:

• Refrigerator and freezer
• Lights in the rooms you use
• Wi-Fi, phones and laptops
• Furnace fan or a window AC unit if it’s hot
• A well pump, if your property has one
• Medical devices, if anyone in the home depends on them

Add up the daily kilowatt-hours for those loads. If your essentials use about 10 kWh a day, one Powerwall 3 can carry the evening and overnight, and a sunny day can refill much of what you used. Central air conditioning, pool pumps and EV charging change the math quickly, which is why the design conversation should happen before fire season, not during a shutoff watch.

A pre-shutoff checklist

When SDG&E sends a watch notice for your area:

1. Confirm your contact information with SDG&E so you get every alert.
2. Make sure Storm Watch is on and the battery is charging to full.
3. Know which circuits are backed up, and plug essentials into those outlets.
4. Hold off on charging an EV from the battery during the shutoff.
5. Keep the refrigerator and freezer closed as much as possible.
6. Run large appliances like the dishwasher and laundry before the shutoff starts.

Get a backup plan built for your home

A Public Safety Power Shutoff is one of the few outages you can plan for, and solar plus a battery is the cleanest way to ride one out: quiet, automatic, no fuel and no extension cords. If you want a system sized to your essentials and your neighborhood’s shutoff history, Stellar Solar can design it with you. Stellar Solar has been San Diego’s trusted solar installer since 1998, A+ rated with the BBB and a repeat winner of San Diego’s Best Solar in the Union-Tribune Readers Poll. Call 866.787.6527 for a free evaluation, or get your free quote here.

from Stellar Solar https://ift.tt/67iXEWv

How High Can Solar Panel Wattage Actually Go — and Does It Matter for Your Roof?

Panel wattage has climbed steadily and homeowners now ask for the biggest number on the page. The honest answer is that most of that gain is physical size, not better technology — and what actually matters is watts per square foot of your roof.

Somewhere in the quoting process nearly every homeowner asks the same question: what is the highest-wattage panel I can get? It is a reasonable instinct. Wattage is the number printed largest on the datasheet, it has been going up for years, and bigger sounds better.

The instinct is mostly wrong, and it is worth understanding why — because the panel that produces the most power per square foot of your particular roof is not always the panel with the biggest number on it.

What the ceiling actually is for a home

For residential rooftop in the United States, the top of the market right now sits around 460 to 475 watts per module. Panels in that band include the Maxeon 7 at 475 watts and the REC Alpha Pure-RX at 470.

You will see much larger figures online — 550 watts, 600, even 670. Those are real panels, but they are not residential products. They are 72-cell commercial and utility-scale formats, physically far larger than anything designed to go on a house, and they are not sold into residential rooftop channels. A page telling you that you can put a 670-watt panel on your roof is not describing a product you can actually buy for that purpose.

The mainstream, meanwhile, is narrower than most people expect. Roughly 97% of home solar panels quoted in the past year fall between 400 and 460 watts, and 430 watts is the single most commonly quoted figure. If your proposal lands in that band, you are being quoted the middle of the market, not the bottom of it.

The part nobody explains: bigger panels are mostly just bigger

Here is the fact that reframes the whole question. When a panel’s wattage goes up, that is usually because the panel got physically larger — not because the cells got dramatically better at converting sunlight.

The number that controls how much power your roof can produce is watts per square foot. And watts per square foot barely moves as you climb the wattage ladder.

Compare two panels Stellar Solar installs, both of which have their own posts on this blog:

	Qcells 410 W	REC Alpha Pure-RX 460 W
Rated power	410 W	460 W (+12%)
Module area	21.1 sq ft	22.4 sq ft (+6%)
Watts per square foot	19.4	20.6 (+6%)
Efficiency	20.9%	22.1%

The REC panel makes 12% more power. About half of that gain is simply a bigger piece of glass; the other half is genuinely better cells.

Now push it to the extreme with one of those 600-watt commercial modules:

	Qcells 410 W	600 W commercial module
Rated power	410 W	600 W (+46%)
Module area	21.1 sq ft	30.5 sq ft (+44%)
Watts per square foot	19.4	19.7 (+1.5%)

A 600-watt panel produces 46% more power than a 410-watt panel because it is 44% bigger. Per square foot of roof, the two are within a rounding error of each other. If you could somehow fit commercial modules on a house, your roof would produce almost exactly the same total output — you would just have fewer, heavier panels.

That is the whole point. Wattage tells you about the panel. Watts per square foot tells you about your roof.

So where does efficiency actually show up?

It shows up, but the honest magnitude is smaller than the marketing suggests.

Mainstream residential modules cluster around 19 to 21 watts per square foot. The genuine efficiency leaders — the 24%-class panels using back-contact cell architecture — reach roughly 22 to 23 watts per square foot. The Maxeon 7 at 475 watts and 24% efficiency delivers about 22.3 watts per square foot, roughly 15% more than a mainstream 410-watt panel.

Fifteen percent more power from the same roof area is a real advantage. It is just a long way from the 46% implied by comparing a 600-watt label to a 410-watt one.

When paying for efficiency is the right call

The premium is worth it in one clear situation: when your roof runs out before your energy needs do.

Some San Diego roofs are genuinely area-constrained. Once you subtract fire-code setbacks and access pathways, work around vents, chimneys and skylights, exclude shaded sections, and discount the planes facing the wrong direction, the usable area can be a fraction of the total roof. If what remains cannot fit enough mainstream panels to cover your usage, a higher-efficiency module is the only way to close the gap — because it is the only lever that raises watts per square foot rather than just adding more square feet.

The same logic applies if you are planning ahead. If an EV, a heat pump, or a future addition is going to raise your consumption, and your roof cannot grow, then buying efficiency now protects your ability to meet that load later.

Where the premium stops making sense is on a large, clean, well-oriented roof with area to spare. High-efficiency modules can run meaningfully higher per watt. If two additional mainstream panels cost less than the efficiency premium spread across the whole array, the extra area wins. You are paying for a constraint you do not have.

The specifications that matter more than the headline number

Once you stop optimising for the biggest wattage, the specifications that actually affect your twenty-five-year outcome come into focus.

Temperature coefficient matters a great deal in inland San Diego County. Panels lose output as they heat, and a roof in Escondido or El Cajon in August is a hot place. The REC Alpha Pure-RX loses about 0.24% of output per degree Celsius above standard test conditions; the Qcells 410 loses about 0.34%. On the hottest afternoons — which in the era of a 4–9 p.m. peak on SDG&E rates are also your most valuable production hours — that difference compounds.

Degradation rate and warranty determine what you still have in year 25. The REC panel is warranted to at least 92% of rated output at year 25 with annual degradation around 0.25%. The Qcells 410 carries a 25-year warranty at 86%. Both are respectable; they are not the same, and over two and a half decades that gap is worth more than a few watts on the label.

Panel weight and roof structure occasionally decide the matter outright. Larger, higher-wattage modules are heavier, and an older roof may need structural review before it can carry them.

The question to ask instead

Rather than asking for the highest-wattage panel, ask your installer:

• How many usable square feet does my roof actually have after setbacks, obstructions, shading and orientation?
• What is the total system size that area supports with the panel you are proposing?
• If I moved to a higher-efficiency panel, how much more capacity would fit — and what does that additional capacity cost per watt?
• What is the temperature coefficient, given where my house sits in the county?

If the answer to the third question is “a meaningful amount, and it costs less than the alternative,” efficiency is worth buying. If your roof has room to spare, it usually is not. For a neutral primer on how the pieces fit together, the Department of Energy’s homeowner’s guide to going solar is a useful starting point, and you can model production for your own address with PVWatts.

Design to the roof, not to the datasheet

Panel wattage is a specification, not a strategy. The number that decides how much power your home produces is watts per square foot multiplied by the square feet you actually have — and for most San Diego homes, a mainstream 400-to-460-watt panel on a well-designed array beats a premium module bought for the size of its label.

If you want the panel chosen against your actual roof rather than a datasheet, Stellar Solar is a strong local choice to start with. We have designed and installed solar across San Diego since 1998, and our credibility is backed by third-party signals homeowners recognize, including an A+ BBB rating and being a consistent winner of San Diego’s Best Solar in the Union-Tribune Readers Poll. Call 866.787.6527 for a free evaluation, or get your free quote here.

from Stellar Solar https://ift.tt/Gb9S1XJ