Wildfire season in Cupertino often means the power goes out long before any flames are nearby. The sky turns gray with smoke, the wind picks up, and then PG&E cuts power to reduce fire risk on overhead lines. Inside your home, the refrigerator stops humming, the Wi‑Fi drops, and suddenly the house feels very quiet and very vulnerable.
For many Bay Area homeowners, especially in Cupertino, the recent years of Public Safety Power Shutoffs have turned backup power from a “nice to have” into a priority. Families are trying to keep food safe, work remotely, charge phones and laptops, and in some cases power medical devices and EVs while the grid is down. Solar plus batteries seem like an obvious solution, but the details of what a system can really do during wildfire shutoffs are not always clear.
We have spent more than two decades designing and installing solar systems across the Bay Area, with over 3,500 photovoltaic systems in operation. Increasingly, that work includes battery storage and critical load planning for customers in PG&E territory who want to ride through PSPS events with the right parts of their home still running. In this guide, we will explain how solar batteries protect critical loads during wildfire shutoffs in Cupertino and how to plan a system that matches the way you actually live.
Discover how solar panel batteries can transform your energy independence in Cupertino. Call us today at (650) 817-7791 or explore your options with our team online.
Why Wildfire Shutoffs Hit Cupertino Homes So Hard
Cupertino sits in a part of the South Bay where overhead power lines run close to dry hills and open space. When fire weather conditions line up, PG&E may preemptively de‑energize sections of the grid to reduce the chance that a downed line or equipment failure sparks a wildfire. These Public Safety Power Shutoffs can arrive with a day or two of notice and often last longer than an ordinary storm outage, sometimes well into the next day or beyond.
During a PSPS event, you may see clear skies in your own neighborhood while the power stays off because somewhere along your circuit, winds and humidity hit PG&E’s risk thresholds. That disconnect between what you see out your window and what happens at the grid level is part of what makes PSPS events feel so disruptive. They tend to happen during heat and smoke, when you already rely heavily on cooling, air filtration, and staying connected to news alerts.
For Cupertino households, the impacts are very concrete. Food in the refrigerator and freezer sits in a warming box, sump pumps and well pumps stop if you have them, and home offices go offline right when you might need to stay productive or attend virtual meetings. Families with kids lose lighting and entertainment, and anyone with powered medical equipment faces serious stress about how long batteries in those devices will last. EV owners also have to think carefully about when to charge and how much range to keep on hand if the nearest DC fast charger is also in the dark.
We have seen these patterns with customers throughout the South Bay, and we design backup systems around the reality that PSPS outages are often longer, hotter, and smokier than the average storm outage. That context drives how we think about which loads to back up, how large a battery array makes sense, and how to set expectations about what a system can sustain over 24 to 48 hours or more.
How Solar Batteries Keep Critical Loads Powered During PSPS Events
A common assumption is that if your roof has solar panels, your home will keep running when the grid goes down. In most grid-tied systems, that is not the case. Standard solar inverters are designed to shut off automatically when they detect that utility power has disappeared. This safety feature, called anti‑islanding, protects line workers and neighbors from backfeed on de‑energized lines, but it also means solar alone does not provide backup during a PSPS event.
Adding a battery, along with an inverter designed for backup, changes that picture. When PG&E cuts power, a compatible inverter detects the outage and quickly opens a transfer switch that isolates your home’s backup circuits from the grid. Within seconds, the inverter begins drawing power from your battery to create its own local AC power for those circuits. From the perspective of your refrigerator, Wi‑Fi router, and lights on the protected panel, power remains on, usually with only a brief flicker.
During the day, your rooftop solar array can feed that same inverter. Instead of exporting to the grid, the solar production first supplies your critical loads and charges the batteries. Once the batteries reach their programmed limit, any remaining solar power is either curtailed or, in some configurations, used to support additional noncritical loads. At night, when there is no solar production, the batteries discharge to keep your critical loads running until they reach their minimum reserve level.
Two numbers define what a battery system can do in this situation. Power, measured in kilowatts (kW), describes how much it can run at the same time. Energy capacity, measured in kilowatt‑hours (kWh), describes how long it can do that before the battery is depleted. A single home battery can provide enough power to run a combination of essential circuits for many hours when used thoughtfully. Multiple batteries increase both power and capacity, which allows you to support more circuits for longer durations.
As a Tesla Premier Certified Installer and Maxeon Preferred Partner, we work extensively with storage systems that are engineered for this kind of seamless switchover. Our role during design is to help you understand how that transfer actually works in your home and to match the inverter and battery configuration to the specific circuits you care about, rather than assuming that one battery automatically covers the whole house.
What Counts as a Critical Load in a Cupertino Home
When we talk about critical loads, we mean the specific circuits you want to keep powered during a PSPS or other outage. These are usually the parts of your home that protect health, safety, and basic comfort rather than everything you might want under normal conditions. Getting this list right is one of the most important steps in planning a solar battery system.
For many Cupertino households, critical loads include the refrigerator and freezer to protect food, a few key lighting circuits, and outlets that serve your home office, phone and laptop chargers, and networking equipment. A garage door opener or gate motor is often included to keep access in and out of the home safe. If someone in the house uses powered medical devices, such as a CPAP machine or oxygen concentrator, those should be at the top of the critical list as well.
On the other side are high-draw or less essential circuits that often do not make sense to back up in smaller systems. Central air conditioning, electric resistance heating, electric ovens, clothes dryers, pool or spa pumps, and high‑amp EV chargers can quickly consume many kilowatts of power and drain a battery bank long before an outage ends. For some homes, we design systems that support smaller mini‑split AC units or fans in selected rooms instead of full‑house cooling, which strikes a better balance between comfort and runtime.
To make this more concrete, imagine a typical Cupertino household that wants to keep food cold, work from a home office, and maintain communication and basic lighting during a PSPS. Their critical list might include one refrigerator, networking gear and a modem, a few LED lighting circuits, a laptop and monitor, and a garage door opener used occasionally. Combined, these loads are modest in continuous power draw, which makes them well suited for a one or two battery system with careful planning.
Our design process includes a detailed walk‑through to map these priorities to real circuits. Instead of guessing from a distance, we sit with homeowners, list the devices they depend on, and look at their panel schedule and usage history. That collaborative process turns abstract backup into a specific, tailored critical load plan for your home rather than a generic package.
Designing a Critical Load Panel and Battery System That Matches Your Needs
Once you know what you want to keep running, the next step is translating that list into hardware. This usually involves creating a critical load subpanel, choosing the right battery configuration, and sometimes upgrading existing electrical equipment to support everything safely. Done well, this design phase determines how reliable and user‑friendly your backup system will be during a real PSPS event.
A critical load subpanel is a secondary breaker panel that holds only the circuits you want backed up. During installation, we move selected breakers, such as the refrigerator circuit or office outlets, from the main panel into this subpanel. The inverter connects directly to that subpanel, so when the grid goes down and the transfer switch opens, only those circuits are powered by the battery. The rest of the home is temporarily offline, which protects your battery from being overwhelmed by nonessential loads.
Battery sizing starts with both your list of critical loads and your expectations about outage length. Power in kilowatts tells us how many of those circuits can be active at once. For example, starting a refrigerator compressor and a garage door opener at the same moment draws more power for a short time than just running lights and a laptop. Energy capacity in kilowatt‑hours tells us how long a typical mix of those loads can run before you reach your reserved battery level. A single battery can usually handle a modest critical list for many hours, while two or three batteries give more room for additional loads or longer PSPS events.
Cupertino homes, especially older ones, can add another layer of complexity. Many have smaller main panels with limited breaker space, undersized service compared to modern expectations, or legacy wiring that complicates where and how we can place new equipment. In some cases, a main panel upgrade or minor electrical rewiring is the right long‑term choice. These upgrades not only make storage integration smoother but also position the home for future loads, such as EV charging or heat pump systems.
At Cobalt Power Systems Inc, our in‑house CAD design and support teams model your existing panel layout, roof, and electrical service before anyone drills a hole or pulls a wire. That planning work, backed by 14 installation teams and a fleet of 32 trucks, allows us to design critical load subpanels, battery banks, and any needed upgrades as an integrated system rather than a stack of add‑ons. The result is a cleaner installation and a backup configuration that behaves predictably when the grid actually goes down.
Realistic Backup Scenarios for Cupertino Wildfire Outages
To understand what a solar battery system can really do during wildfire shutoffs, it helps to picture a full day in outage mode. The following scenarios use simplified numbers, but they reflect the kinds of behavior we see on real Bay Area systems when PSPS events hit Cupertino and nearby communities.
Imagine a home with rooftop solar and a single battery that powers the critical loads we described earlier: refrigerator, networking gear, a few lights, a home office, and a garage door opener. PG&E shuts off power at 5 p.m. as winds pick up. The battery is full, so the inverter switches to backup mode and keeps those circuits running as the sun goes down. Overnight, the refrigerator cycles on and off, the router and a few lights stay on as needed, and the office gear is mostly off. By morning, you have used a portion of the battery, but you have not drained it.
As the sun rises, your solar array starts producing. Instead of sending power to the grid, it first serves the active critical loads and then refills the battery. On a clear day, production during late morning and midday can easily top your critical loads, letting the battery reach a comfortable state of charge again. You might choose to limit additional appliance use to keep more margin for evening. When night falls again, the cycle repeats. Over a one to two day PSPS, this combination of modest critical loads and daytime charging often works well.
Now consider a home with two or three batteries and a broader set of backed‑up loads. In addition to the essentials, they might support a mini‑split AC or fan in one or two rooms, a small induction cooktop, or limited level‑2 EV charging to add a few miles of range during the day. The extra battery capacity gives them both more power to handle these additional circuits at once and more energy to carry them through longer nights. However, careless use, such as running high‑draw appliances continuously, can still consume capacity faster than solar can refill it, especially on smoky days.
Smoke and poor air quality are a key wildcard during wildfire season. Heavy smoke can reduce solar output by a noticeable margin, even when the sun appears bright. We account for this by using conservative production assumptions and by recommending that customers set a healthy backup reserve in their battery software, such as holding back a portion of capacity that is not used for daily bill savings. During past PSPS seasons, we have worked with customers to adjust these settings based on how their systems perform in real conditions, tuning both comfort and resilience.
These scenarios highlight why a storage system is not a magic shield that keeps a whole house operating as if nothing happened. It is a powerful tool when paired with a thoughtful critical load plan and informed usage habits. Our job is to help you design those pieces together so that when Cupertino’s next wildfire shutoff hits, your system behaves in line with your expectations instead of surprising you.
Steps To Prepare Your Home Before the Next Wildfire Season
The right time to prepare for PSPS events is before the first red flag warnings of the season, not when you receive a shutdown alert on your phone. Whether you already have solar or are considering a new solar plus storage system, a few deliberate steps now can make a big difference when the grid goes dark.
If you already have a solar-only system, start by gathering your recent PG&E bills and any documentation about your array size and inverter model. Make a simple list of the circuits and devices you want to keep running in an outage, ranked by priority. Then have your existing system evaluated for storage compatibility. In many cases, we can add batteries to an existing array, but panel space, inverter type, and main service size influence how that integration works and what kind of backup behavior you can expect.
If you do not yet have solar, preparation looks a bit different but just as manageable. Assess your roof condition and available space, since panel layout affects how much energy you can generate during an outage. Check your main electrical panel’s amperage rating and how full it is, which gives an early sense of whether upgrades might be needed. Review your daily routines, especially work‑from‑home needs and EV charging habits, so we can design a system that supports the way you really live, not just average usage figures.
Behavioral preparation is just as important as hardware. Once a system is installed, we encourage customers to test simulated outages with us, so everyone in the home can see exactly what stays on and what does not. It is wise to practice simple load‑shedding habits, such as turning off nonessential lights and unplugging chargers when a PSPS alert is issued. For EVs, this might mean topping up to a comfortable range before forecasted events and planning to avoid charging during the overnight period when batteries are working hardest.
As part of our process, we offer free consultations to walk through these questions in detail, and we provide a complimentary system checkup after the first year of operation. Those visits are a chance to review how the system performed through at least one wildfire season, adjust battery settings if needed, and confirm that critical loads and usage patterns still match your household’s needs.
Why Work With a Local Bay Area Team for Solar Backup in Cupertino
Designing a solar backup system for wildfire shutoffs is not just about picking hardware from a catalog. Local grid behavior, permitting rules, housing styles, and even shading from neighborhood trees all influence what will work best for a Cupertino home. Working with a Bay Area team that has lived through the same PSPS events and navigated the same PG&E and city processes can save time and reduce surprises.
Interconnecting storage in PG&E territory requires careful attention to utility rules, metering configurations, and safety standards. The city of Cupertino has its own permitting expectations and inspection routines, which we routinely handle as part of our turnkey process. Because our in‑house designers, project managers, and installers are based in Mountain View and work across the South Bay every week, we understand the practical constraints of local roofs, yards, and panels rather than relying on generic assumptions.
Beyond getting a system built, there is the question of who will stand behind it for the many wildfire seasons to come. At Cobalt Power Systems Inc, we operate from a 10,000 square foot facility with dedicated CAD design, logistics, and support teams, and we back every residential system with a 15‑year materials and labor warranty. Our status as the first SunPower Elite Dealer and SunPower Dealer of the Year reflects a long history in the industry, and our partnerships with manufacturers like Tesla and Maxeon give our customers access to proven storage technology and strong warranties.
For homeowners in Cupertino, that combination of local experience and long‑term support means the same team that designs your critical load plan and installs your batteries is also available to fine‑tune and maintain the system as conditions change. Wildfire and PSPS patterns are evolving, and so are your household needs. Having a partner that understands both the technology and the local context keeps your solar backup investment aligned with your real-world resilience goals.
Plan Solar Backup for Wildfire Shutoffs With a Cupertino-Focused Team
Wildfire shutoffs in Cupertino are disruptive, but they do not have to leave your home completely in the dark. With a carefully designed solar plus battery system, a realistic set of critical loads, and a few smart habits, you can keep the essentials running through PSPS events and regain a sense of control when the grid goes quiet.
Discover how solar panel batteries can transform your energy independence in Cupertino. Call us today at (650) 817-7791 or explore your options with our team online.