Solar During Grid Outages: Why Panels Shut Down Without a Battery, and What Actually Provides Backup in California

Adrian Marin|Independent Solar Advisor, Temecula CA

Helping Riverside County homeowners navigate SCE rates and solar options since 2020

Most Temecula homeowners are stunned to discover their solar panels stop producing the instant the grid goes down. Even at noon on a cloudless day. Here is why that happens, what the law actually requires, and the three real ways to keep your home running during a Public Safety Power Shutoff in SCE territory.

The Surprise Most Solar Owners Discover During Their First PSPS

The 100-degree afternoon, the Santa Ana winds picking up across the inland valleys, the SCE notification pinging your phone: Public Safety Power Shutoff scheduled to start in four hours. Your house goes dark. You step outside, look up at your roof, and see 28 solar panels sitting in direct sunlight doing absolutely nothing.

This is the moment most solar customers in Temecula learn what their installer either did not explain clearly or said once in passing during the sales presentation. A standard grid-tied solar system, the kind that 80 to 85 percent of California homeowners actually installed, produces zero power during a grid outage. The panels are physically capable. The inverter is physically capable. The wiring is intact. The system is operating exactly as the engineering requires.

It is not a fault. It is not a bug. It is a legal safety feature, and once you understand why, the design makes perfect sense. The question is whether you accept the limitation or pay for one of the three configurations that work around it.

Anti-Islanding: The UL 1741 and IEEE 1547 Rule That Shuts Your Panels Off

Every grid-tied solar inverter sold in the United States is required to comply with UL 1741 and IEEE 1547. These two standards govern how distributed energy resources interact with the utility grid. Inside both standards is a rule called anti-islanding protection.

The rule says: when the inverter detects that the utility grid is no longer present, energized, or operating within normal voltage and frequency limits, it must disconnect from the grid within 2 seconds and stop producing AC power. The inverter holds itself open until it detects a stable utility grid for a continuous period (typically 5 minutes) before reconnecting.

The reason is straightforward and not negotiable. When a tree falls on a 12 kV distribution line in Wildomar and the wire ends up across someone's driveway, SCE dispatches a line crew. That crew arrives at the substation, opens the breaker, locks it out, tags it, and walks down to the wire assuming the line is dead. If your solar inverter is happily back-feeding power onto that line because the sun is shining, the lineman touching the wire dies.

Anti-islanding prevents that scenario. Your panels do not make their own little grid in the middle of a dead utility grid because if they did, line workers could not safely assume any downed wire is de-energized. The 2-second disconnect window exists so that even fast-acting utility protection schemes have a guaranteed safe state.

This is true for every standard grid-tied inverter on the market: Enphase IQ7, IQ7Plus, IQ7X, the SolarEdge HD-Wave, the older SMA Sunny Boy, every string inverter from Fronius, Delta, SolarEdge, and Tesla's own grid-tied inverters. None of them are allowed to produce power into a home that is disconnected from the utility, unless they can prove they have safely formed their own isolated microgrid, which is exactly what island mode and Sunlight Backup are designed to do.

The Three Real Ways to Get Solar Production During an Outage

If anti-islanding shuts off every standard grid-tied system, how do some solar homes keep running during a PSPS? Three configurations get around the rule, all of them by satisfying a different clause of the same standards.

Option 1: Battery with backup mode. A battery system (Tesla Powerwall 3, Enphase IQ Battery 5P, SunPower SunVault) includes its own grid-forming inverter. When the utility drops, the battery's inverter creates an isolated microgrid inside your home, the solar panels see this microgrid as their grid reference, and production continues. An automatic transfer switch physically isolates your home from the utility during this period so back-feeding is impossible. This is the most complete solution.

Option 2: Enphase Sunlight Backup with IQ8 microinverters (no battery). The IQ8 series is the only residential microinverter family on the market that can form its own grid. With an Enphase System Controller and the right wiring, IQ8 panels make a microgrid during daylight without a battery present. Production is limited to roughly 50 percent of array nameplate, there is no power at night, and any unused production is curtailed. Significantly cheaper than a battery, significantly less capable.

Option 3: Generator hybrid. A propane or natural gas standby generator with an automatic transfer switch, integrated alongside solar and optionally a battery. The generator handles outages directly. Solar continues to provide bill savings during normal operation. This is the least common residential configuration in California because PSPS events are typically too short to justify the generator capital cost when a battery does the same job with no fuel logistics.

The right choice for your Temecula home depends on how long the PSPS events in your zone tend to run, how much of your house you want to keep operating, and how cost-sensitive the decision is.

Enphase IQ8 and Sunlight Backup: The Daylight-Only Option Explained

Enphase introduced the IQ8 microinverter line in 2022. Its standout feature is grid-forming capability, which Enphase markets as Sunlight Backup. Until IQ8, no residential solar product on the market could legally produce power during an outage without a battery present. IQ8 changed that.

The way it works: each IQ8 microinverter contains a fast-acting controller that monitors its local grid environment thousands of times per second. When the grid drops, the IQ8 microinverters coordinate via the Enphase System Controller (formerly called the Envoy or IQ Combiner) to form their own AC microgrid. The system controller manages an automatic transfer switch that physically separates your home from the utility during this period.

The limitations are real and worth understanding before you assume Sunlight Backup solves your outage problem:

• Production is capped at roughly 50 percent of array nameplate. A 10 kW array provides up to 5 kW of usable power during Sunlight Backup operation. This is because the system needs production headroom to handle sudden load changes (a refrigerator compressor kicking on) without collapsing the microgrid.
• Loads must stay roughly balanced against production. If a cloud passes overhead and production drops faster than loads, the microgrid shuts down for safety. The system then attempts to reform after a brief delay.
• Zero power at night. No battery means nothing is stored. Once the sun sets, the house is dark until morning.
• Heavy overcast or smoke can reduce production below the threshold needed to maintain the microgrid, and the system trips off.
• Production above what your loads can consume is curtailed. You cannot store the excess because there is no battery.

For a homeowner who wants to keep a refrigerator running and charge phones during a daytime PSPS, Sunlight Backup at $1,000 to $2,000 of added equipment cost over a standard IQ7 system is a reasonable purchase. For anyone who actually needs reliable backup including overnight, it is a partial solution and a battery should be in the plan.

Tesla Powerwall 3: Whole-Home Backup That Actually Runs the AC

The Tesla Powerwall 3 changed the residential backup conversation in California when it launched in mid-2024. The original Powerwall and Powerwall+ delivered 5 to 7 kW of continuous output, enough to run essential loads but not enough to handle a central air conditioner starting up while the fridge compressor was already running.

The Powerwall 3 delivers 11.5 kW continuous and around 30 kW peak (for 10 to 30 seconds, which covers AC compressor startup inrush). At that output, a single Powerwall 3 can run nearly everything in a typical 2,500-square-foot Temecula home simultaneously, including a 4-ton air conditioner. Two units in parallel reach 23 kW continuous and roughly double the storage to 27 kWh, which covers larger homes with multiple AC zones or pool pumps.

For PSPS scenarios, the Powerwall 3 is the most capable single-unit residential battery on the market. Storage capacity is 13.5 kWh, which combined with solar recharging covers the typical 12 to 48 hour SCE shutoff event without rationing. The 11.5 kW output means you do not have to think about which appliances are running. The AC can stay on. The microwave works. The oven works. Life inside the house feels normal except that the lights stay on while every other house on the street is dark.

Powerwall 3 includes a built-in solar inverter that can directly accept DC from up to six solar strings rated at 600V each. This integration cuts installation complexity and cost compared to retrofit configurations where the existing solar inverter remains in place.

Powerwall vs Powerwall 3: How Backup Behavior Differs

Many Temecula homes installed before 2024 have the original Powerwall (5 kW continuous, 7 kW peak) or Powerwall+ (5.8 kW continuous, 9.6 kW peak with sunshine boost). These are still excellent batteries for solar self-consumption and critical-load backup, but they behave differently during an outage than a Powerwall 3.

With an original Powerwall providing 5 kW continuous, central AC is usually impossible unless your unit is small (2 tons or less) and on a soft-start kit. Most homeowners with the original Powerwall set up a critical loads panel that excludes the AC, oven, electric dryer, and EV charger. The backup runs the essentials reliably for the duration of the outage. The AC waits until grid power returns.

The Powerwall 3 does not require that compromise. Most homes can switch to whole-home backup configurations, where the entire main panel is on the battery's backup gateway and every circuit stays live during an outage. The only loads typically excluded are very high-draw items like Level 2 EV chargers (7 to 11 kW continuous would drain a 13.5 kWh battery in 1 to 2 hours) and electric dryers running at full heat.

If you have an older Powerwall and want whole-home backup capability during a PSPS, you have two paths. Add a second original Powerwall in parallel (output doubles to 10 kW continuous, storage doubles to 27 kWh), or replace with a Powerwall 3 unit. Tesla's trade-in path is limited, so the second-unit addition is usually the more practical choice for existing customers.

Critical Loads Panel vs Whole-Home Backup: The Cost Spread

The decision between partial-home backup (critical loads panel) and whole-home backup affects both installation complexity and final cost. The spread is significant. Critical loads backup at a typical Temecula installation runs $14,000 to $18,000 installed for a single Powerwall 3 with critical loads sub-panel work. Whole-home backup on the same battery runs $22,000 to $30,000 installed because the main service panel often needs to be upgraded to handle the battery's bi-directional power flow, and a larger backup gateway is required.

Critical loads panel sizing for a typical Temecula home covers:

• Refrigerator and chest freezer (continuous 150 to 250 watts, peak 800 watts on compressor start)
• Internet modem and Wi-Fi router (under 50 watts)
• Furnace blower or central thermostat (300 to 800 watts when running)
• Garage door opener (one circuit, intermittent draw)
• Two to four lighting circuits (LED throughout: 50 to 200 watts total)
• One outlet circuit per bedroom for phone charging, CPAP, or other small medical devices (100 to 300 watts)
• One kitchen outlet circuit for coffee maker and microwave use (intermittent 1,000 to 1,500 watts when in use)

That stack typically draws 4 to 6 kW peak and 8 to 12 kWh per day during steady operation. A 13.5 kWh Powerwall 3 covers it comfortably with solar recharging during daylight, which is exactly the design target for most PSPS scenarios in SW Riverside County.

Whole-home backup adds central AC (3 to 5 kW continuous), electric range and oven (up to 7 kW peak during cooking), and any other high-draw appliances. The Powerwall 3 handles these because of its 11.5 kW continuous rating, but daily consumption can jump to 30 to 50 kWh and you become more dependent on solar production to recharge through the outage.

PSPS Frequency and Duration in SW Riverside HFTD Zones

SCE's High Fire Threat District map divides its service territory into Tier 2 (elevated risk) and Tier 3 (extreme risk) zones. Parts of Temecula (including the wine country east of town and the foothill neighborhoods along De Portola Road and Calle Contento), most of Wildomar's eastern hills, the De Luz corridor, and the eastern edges of Murrieta and Lake Elsinore fall inside these zones. Western Temecula and the I-15 corridor are mostly outside the HFTD boundary.

PSPS events in SW Riverside County have ranged in duration and frequency depending on Santa Ana wind activity each season. Some years see one or two events totaling 8 to 16 hours of de-energization. Other years, particularly during dry late-fall windows when humidity drops below 15 percent and gusts exceed 50 mph, multiple events stack up across October and November and individual neighborhoods can experience 24 to 48 hours of cumulative shutoff time.

You can check your address against the current SCE HFTD map and PSPS history using SCE's online tools. If your neighborhood has experienced a PSPS in the last three years, treat backup capability as a meaningful design factor, not an optional add-on. If your address is outside the HFTD entirely, the resilience value of a battery is lower (rolling blackouts and storm outages still happen but are less frequent), and the decision shifts toward the bill-savings economics under NEM 3.0.

Sizing a Battery for 24 to 48 Hours of Real Backup

The sizing math for backup is more useful than the marketing capacity number on the battery's spec sheet. A 13.5 kWh Powerwall does not give you 13.5 kWh of usable backup. It gives you a starting reserve, and the duration depends on what loads you run and how much solar production recharges the battery during daylight.

Worked example for a typical 2,800-square-foot Temecula home on critical loads during an October PSPS:

• Critical loads consumption: 10 kWh per 24-hour period
• 10 kW solar array production in October on a clear day: 50 to 55 kWh
• Production above critical load consumption: 40 to 45 kWh available to recharge the battery
• Battery recharge limit per day (Powerwall 3): full 13.5 kWh recharge possible within 2 to 3 hours of midday production
• Excess solar production above what fits in the battery is curtailed (clipped) during the outage
• Effective backup duration: as long as the PSPS lasts, indefinitely on this load profile

For whole-home backup with central AC running through October afternoon heat:

• Whole-home consumption: 35 to 45 kWh per 24-hour period
• 10 kW solar array production in October: 50 to 55 kWh on clear days, 30 to 35 kWh on overcast days
• Net daily surplus: 5 to 20 kWh on clear days (battery recharges), zero to negative on overcast days (battery drains by 5 to 10 kWh per day)
• Effective backup duration on a single Powerwall 3: indefinite on clear-day weather, 2 to 4 days into a stormy outage before depletion
• Backup duration on two Powerwall 3 units in parallel: indefinite for nearly any realistic PSPS scenario in this region

This is why backup design is not just about battery capacity, it is about the relationship between your battery, your solar array, and your daily load profile during the worst weather period when you actually need the system to work. A homeowner planning for the rare 72-hour storm outage during a January atmospheric river needs to size differently than a homeowner planning for an October Santa Ana PSPS where afternoon sun is reliable.

What Happens to Excess Solar When the Battery Is Full

During grid-tied operation under NEM 3.0, excess solar production exports to the grid for credit at the avoided cost rate (5 to 8 cents per kWh). During an island-mode outage, the grid is not available, and the system has nowhere to send the excess.

The inverter or microinverter response: clip the production back to match the current load. Solar panels are designed to do this without damage. They simply produce less than their nameplate when commanded to. The downside is real but bounded: during a multi-day PSPS with the battery already full by 11am, your solar array produces only what your house is consuming for the rest of the day. The remaining potential 30 to 40 kWh of generation is curtailed and lost.

There are a few ways homeowners use this idle production constructively. Run the EV charger during the curtailed hours (load up the car instead of letting the array clip). Pre-cool the house aggressively in the afternoon so the AC runs less after sunset. Run the dishwasher and laundry during peak solar hours. All of these shift load into the production window and reduce the amount of curtailment while extending battery reserve into the evening.

Rapid Shutdown, AC and DC Disconnects, and Permitting Requirements

Every solar installation permitted in Riverside County must comply with the National Electrical Code, including NEC 690.12 Rapid Shutdown. This code requires the system to drop DC voltages to safe levels (within 30 volts of any conductor pair) within 30 seconds when an emergency switch is activated. The switch is typically located at the AC service entrance for first responder access.

Rapid Shutdown affects equipment selection. Module-level power electronics like Enphase microinverters and SolarEdge optimizers handle the requirement at the panel level (each panel shuts down individually). Older string inverter systems without optimizers cannot meet the latest Rapid Shutdown rules and are generally not permitted in new installations in California.

The other required components: AC disconnect at the service entrance, DC disconnect at the inverter, and (for systems with battery backup) a transfer switch that physically isolates the home from the grid during island operation. All of these are standard, included in any properly priced installation, and required for the system to pass the inspection that triggers Permission To Operate from SCE. None of them affect backup behavior beyond meeting safety code.

Generator Backup Integration: When It Actually Makes Sense

For most Temecula homes with solar plus a Powerwall 3, a standby generator is unnecessary expense. The PSPS events that actually occur in this region rarely exceed 48 hours, and a properly sized battery with solar recharge handles those cleanly. Generator capital cost ($8,000 to $15,000 for a 14 to 22 kW natural gas or propane standby unit installed) plus the ongoing fuel logistics rarely justify themselves for occasional shutoffs.

The exceptions where a generator does make sense:

• Households with critical medical equipment that must remain powered regardless of weather (oxygen concentrators, dialysis machines, infant CPAP). A multi-day storm outage that depletes a battery cannot be allowed to happen.
• Heavily shaded properties where winter solar production averages 15 to 25 kWh per day rather than 40 to 55 kWh. The battery cannot reliably recharge during a stormy winter outage, and the generator covers the gap.
• Larger acreage properties with wells (well pumps draw 2 to 5 kW continuous) where losing water service is a real consequence and the battery alone cannot sustain a multi-day outage.
• Existing customers who already have a propane tank installed for a fireplace or pool heater. The marginal cost of adding generator capability is much lower when fuel infrastructure exists.

When a generator is part of the design, the integration matters. An automatic transfer switch coordinates utility, solar, battery, and generator so each source operates at the right time without conflict. Manual transfer setups, where the homeowner has to walk outside and physically throw a switch during an outage, are cheaper but defeat the unattended-backup advantage that justifies the generator in the first place.

Sizing Solar to Support Battery Recharging During a Multi-Day Outage

The single most common mistake in backup system design is undersizing the solar array relative to the loads the homeowner actually wants to run during an outage. A 6 kW solar array paired with a Powerwall 3 looks fine on paper for a bill-savings calculation. The same combination fails during a 60-hour PSPS where the house is running whole-home backup with the AC on, because the solar array cannot produce enough during daylight to recharge what the AC drained overnight.

The sizing rule of thumb for multi-day backup capability: your solar array should produce at least 1.5 times your daily backup-mode consumption on a typical day, so that even on a partly cloudy day the battery returns to full charge before sunset.

Worked example for a 2,800-square-foot Temecula home that wants whole-home backup capability including AC:

• Whole-home backup daily consumption: 40 kWh per day
• Target solar production: 40 x 1.5 = 60 kWh per day
• System size required at Temecula's average 4.2 to 4.5 production hours per kW per day: roughly 13 to 14 kW DC
• That sizes up from a basic 8 to 10 kW bill-offset array to a larger 13 to 14 kW backup-capable array
• Marginal cost of the extra 3 to 6 kW of solar at $2.50 per watt: $7,500 to $15,000 before incentives, $5,250 to $10,500 after the 30 percent federal tax credit

That extra solar pays for itself faster than the battery does on bill-savings math, because every additional kWh produced has economic value 365 days per year even when you are not in an outage. The reason most installers undersize the array is sales positioning, not engineering. A bigger array means a bigger quote and more sales friction. A homeowner who actually wants reliable backup should explicitly ask for the array sized to the backup target, not the bill-offset target.

What to Ask Your Solar Installer Before You Sign

Once you understand how anti-islanding, Sunlight Backup, and battery island mode work, the questions you should ask any installer become specific and answerable. Vague answers from a sales rep about "yes we have backup" are a signal to walk away. The right questions:

• Is this system grid-tied only, grid-tied with Sunlight Backup, or grid-tied with battery backup? Get the configuration in writing on the proposal.
• If battery backup, what is the continuous output rating in kW and how does it compare to my home's typical peak load? Get the kW number, not just the kWh storage number.
• If critical loads backup, exactly which circuits will be on the backup panel and which will be excluded? Get the circuit list in writing before installation.
• If whole-home backup, is my main service panel rated for the bi-directional power flow? Do I need a main panel upgrade? What does that cost?
• How does the system behave when the battery is full during a PSPS? Is excess solar curtailed or is there an option to dump it to a non-critical load like an EV charger?
• If we lose the grid mid-afternoon on a hot day with the AC running, what does the homeowner experience? Any momentary interruption? Any loads that need to be reset?
• Is the system designed to handle a 48-hour to 72-hour outage on whole-home backup including AC, or only on critical loads? What is the recharge math?

A competent installer answers these questions directly with numbers and configuration details. A sales-driven installer answers with marketing phrases. Use the difference to filter.

Cost Stack: What Backup Actually Adds to a Solar Project

Putting real numbers against the three backup configurations matters because the marketing tends to blur the cost spread. Here is what the configurations actually run in Riverside County in 2026, before incentives:

• Grid-tied solar only, no backup: 10 kW system at $2.40 to $2.80 per watt installed runs $24,000 to $28,000. Zero backup capability. Panels shut off the instant the grid goes down.
• Grid-tied IQ8 with Sunlight Backup, no battery: Same 10 kW system upgraded to IQ8 microinverters with the Enphase System Controller adds roughly $1,000 to $2,000 to the project. Total: $25,000 to $30,000. Daylight-only backup, capped at roughly 50 percent of nameplate, no overnight power.
• Grid-tied solar plus single Powerwall 3, critical loads backup: 10 kW solar plus one Powerwall 3 with critical loads sub-panel: $36,000 to $44,000 installed. After 30 percent federal tax credit on the full system and an SGIP rebate of $2,700 to $5,400 on the battery: net cost typically $20,000 to $28,000.
• Grid-tied solar plus single Powerwall 3, whole-home backup: 10 to 13 kW solar plus one Powerwall 3 with whole-home backup gateway and possible main panel upgrade: $42,000 to $55,000 installed. Net cost after incentives typically $26,000 to $36,000.
• Grid-tied solar plus two Powerwall 3 units, whole-home backup, multi-day capability: 13 to 14 kW solar plus two Powerwall 3 units in parallel: $54,000 to $68,000 installed. Net cost after incentives typically $34,000 to $44,000.

The spread from no backup to robust two-Powerwall whole-home backup is roughly $10,000 to $16,000 of net cost after incentives. That is the price of resilience. Each homeowner has to decide how much that resilience is worth against the alternative of riding out a PSPS without power. For HFTD residents with medical equipment, work-from-home obligations, or pets that cannot tolerate a hot dark house, the answer is often clear. For homeowners outside the HFTD with flexible schedules, the value is lower and a simpler battery configuration may be enough.

Common Misunderstandings About Solar Backup

A few myths persist among Temecula homeowners and even some less-experienced solar sales reps. Worth correcting before you sit down for a proposal.

"My solar panels will keep my house running during an outage because I have them." No. Without a battery or IQ8 Sunlight Backup, your panels stop producing when the grid drops. This is the source of most homeowner frustration after the first PSPS.

"A 13.5 kWh battery means I get 13.5 hours of backup at 1 kW." The math is correct in isolation but ignores solar recharging. In real outages during daylight, solar production refills the battery, and the effective backup duration is much longer than the static capacity number suggests.

"Battery backup means my whole house keeps running like nothing happened." Only if the configuration is whole-home backup with sufficient continuous output to handle every load. Critical loads backup is intentionally narrower and excludes high-draw appliances. Know which configuration is in your proposal.

"Sunlight Backup is the same thing as a battery." No. Sunlight Backup provides limited daylight-only power with significant production restrictions. It is a complement to a real backup strategy or a budget option for homeowners who want some daytime resilience without a battery's cost, not a substitute for true island-mode battery operation.

"My solar installer will explain all of this in the sales call." Some will. Many will not, because the conversation makes the proposal more complicated and risks losing the sale to a competitor who skips the nuance. The homeowners who end up frustrated after their first PSPS are usually the ones whose installer never had the anti-islanding conversation upfront.

Frequently Asked Questions

Why does my grid-tied solar system shut off during a power outage?

Grid-tied inverters are required by UL 1741 and IEEE 1547 to disconnect from the grid within 2 seconds of detecting a grid loss. This is called anti-islanding protection. It exists to keep utility line workers safe. If your panels kept sending power onto the grid during an outage, a lineman touching a downed wire could be electrocuted by your system. Without a battery or an IQ8 system configured for Sunlight Backup, your panels stop producing the moment the grid goes down, even at noon on a sunny day.

What is Enphase Sunlight Backup and how is it different from a battery?

Sunlight Backup is an Enphase IQ8 feature that lets your microinverters form their own grid when the utility is offline. It provides daylight-only backup power without a battery, but production is limited to roughly 50 percent of your array nameplate to keep the local microgrid stable. You get no power at night, no power on heavy overcast, and any unused production is curtailed. It is useful as a partial solution, but it is not the same as battery backup.

Can a Tesla Powerwall 3 run my whole house including the air conditioner?

A single Powerwall 3 delivers 11.5 kW of continuous output and around 30 kW of peak output for motor starts. That is enough to run a typical Temecula home including a central AC unit, refrigerator, lights, and standard outlets simultaneously. Two Powerwall 3 units in parallel push continuous output to 23 kW and roughly double the storage to 27 kWh, which covers larger homes with two AC units or higher peak draws.

Is Temecula in a Public Safety Power Shutoff zone?

Parts of Temecula, Murrieta, Wildomar, and Lake Elsinore fall within SCE High Fire Threat District Tier 2 and Tier 3 zones. SCE has executed PSPS de-energizations in these areas during Santa Ana wind events, with some shutoffs lasting more than 24 hours. You can check your address on the SCE PSPS lookup tool. If you are inside an HFTD boundary, battery backup is worth weighting heavily even when the bill-savings math is borderline.

What loads should I put on a critical loads panel for backup?

Typical Temecula critical loads include the refrigerator, internet router and modem, a few lighting circuits, garage door opener, one outlet circuit per bedroom for phone charging or medical equipment, and the furnace or thermostat for winter heating. That stack usually draws 4 to 6 kW continuous and 8 to 10 kWh per day, which a 13.5 kWh battery covers comfortably. Central AC, electric dryers, EV charging, and electric ovens are usually excluded unless you size up to whole-home backup.

How long will a Powerwall 3 keep my house running during a PSPS?

On critical loads alone (4 to 6 kW continuous, 8 to 10 kWh per day), a 13.5 kWh Powerwall 3 with solar recharging provides backup for the full duration of most PSPS events, typically 12 to 48 hours. On whole-home backup with central AC running, a single Powerwall might run for 6 to 10 hours on stored energy, with solar extending coverage during daylight. For multi-day outages with AC, most installers recommend two Powerwall 3 units.

Do I need a generator if I already have solar plus a battery?

For most Temecula homeowners, no. A properly sized solar plus battery system handles the PSPS events that actually happen in this area without needing a generator. The exception is homeowners who need uninterrupted power for medical equipment regardless of weather, or who live in heavily shaded properties where winter solar production is too low to recharge the battery during a multi-day storm outage. In those cases, an automatic transfer switch and a propane or natural gas generator integrates with the battery system as a third tier of backup.

What is Rapid Shutdown and how does it affect backup operation?

Rapid Shutdown (NEC 690.12) requires solar systems to be able to drop DC voltages to safe levels within 30 seconds when an emergency switch is pressed. This is a firefighter safety feature, not a backup feature. It does not affect normal island mode operation. Both Tesla and Enphase systems are Rapid Shutdown compliant by default. The required AC and DC disconnects are part of every permitted installation in Riverside County.