How do I prioritize circuits when my home battery is running low during an extended outage?

Follow a four-tier load shedding strategy: Tier 1 (Critical) includes refrigerator, medical devices, and lighting — keep these on until your battery drops below 10%. Tier 2 (Essential) includes internet, garage door, furnace controls, and water pump — shed these at 20% battery. Tier 3 (Convenience) includes TV, laundry, and dishwasher — turn off at 40% battery. Tier 4 (Deferred) includes EV charging, electric dryer, and whole-house AC — disconnect immediately when the outage begins unless you have 20+ kWh of capacity.

What is load shedding on a home battery system and how does it work?

Load shedding is the automated or manual process of disconnecting non-essential circuits to extend battery backup time during an outage. Smart panels like Span Panel, Schneider Pulse, and Lumin selectively turn off circuits based on battery state of charge. Tesla Powerwall 3 supports load shedding through its Backup Gateway and app-controlled circuit priorities. Enphase IQ Battery systems use the IQ System Controller to manage up to 12 essential circuits. FranklinWH aGate enables circuit-level priority settings through its mobile app.

How long can I run my refrigerator on battery backup during a power outage?

A standard refrigerator drawing 150-400W (1-2 kWh/day) can run for 24-48 hours on a 13.5 kWh Tesla Powerwall 3, consuming only 8-15% of total capacity per day. During a 72-hour outage, the refrigerator alone uses 3-6 kWh, leaving 7.5-10.5 kWh for other critical loads. For maximum efficiency, avoid opening the fridge unnecessarily during outages and ensure the refrigerator is on its own dedicated circuit in your critical loads panel.

Can I power my well pump on a home battery during an outage, and how much capacity does it use?

Yes, a ½ HP well pump drawing 1,000W start-up (surge) and 600-800W running can be powered by a 13.5+ kWh battery. A well pump uses approximately 0.5-1.0 kWh per day for a family of four. Wire the well pump to your critical loads panel as a Tier 2 (Essential) circuit. During a 24-hour outage, expect the well pump to cycle 4-6 times for 10 minutes each, consuming 0.4-0.8 kWh total. For homes in wildfire or hurricane zones, prioritize the well pump above all non-medical loads.

What battery capacity do I need for 24, 48, and 72 hours of outage backup?

For 24 hours of Tier 1 + Tier 2 backup (refrigerator, lights, internet, medical, furnace controls, well pump), you need 5-8 kWh of usable capacity. For 48 hours, budget 10-16 kWh. For 72 hours, plan for 15-24 kWh. A single Tesla Powerwall 3 (13.5 kWh) covers 36-48 hours of Tier 1+2 loads. FranklinWH aPower 2 (20 kWh) covers 60-72 hours. Adding a 5 kW solar array extends all durations by 2-3x during sunny weather, producing 15-25 kWh per day for recharging.

How do I configure load shedding on a Tesla Powerwall 3 during an outage?

In the Tesla app, navigate to Settings > Backup > Storm Watch to enable automatic weather-based preparation. During an active outage, use the Tesla app's Time-Based Control or Custom priority settings to manage which circuits stay active. The Tesla Powerwall 3 integrates with the Tesla Backup Gateway or supported smart panels (Span, Lumin) for circuit-level load shedding. Without a smart panel, you manually flip breakers on non-essential circuits in your critical loads subpanel. Set your Backup Reserve to at least 20% to preserve Tier 1 capacity for extended outages.

Should I run my heating or air conditioning on battery during a winter storm or hurricane outage?

Central HVAC (3,000-5,000W) will drain a 13.5 kWh battery in 2-4 hours and should be deferred unless you have 20+ kWh capacity. Instead, power a single high-efficiency mini-split heat pump (700-1,200W) as a Tier 3 circuit, which provides heating or cooling to one room for 8-12 hours on 13.5 kWh. For gas furnaces, only the blower motor and controls (300-500W) need battery power — the furnace itself runs on natural gas or propane. In winter storm scenarios, prioritize furnace blower and heating controls above all non-medical loads.

How much does it cost per hour to run each tier of home battery backup during an outage?

Based on the average U.S. electricity rate of $0.16/kWh, Tier 1 loads (refrigerator + lights + phone charging) cost approximately $0.03-0.05/hour in energy equivalent. Tier 2 (adding internet, furnace blower, well pump) raises it to $0.08-0.12/hour. Tier 3 (adding TV, dishwasher, laundry) costs $0.20-0.35/hour. Tier 4 (EV charging, electric dryer, whole-house AC) adds $0.50-1.20/hour. With solar recharging during daylight, effective costs drop to near $0 for Tier 1-2 loads during sunny multi-day outages.

How do I prioritize circuits when my home battery is running low during an extended outage?

Follow a four-tier load shedding strategy: Tier 1 (Critical) includes refrigerator, medical devices, and lighting — keep these on until your battery drops below 10%. Tier 2 (Essential) includes internet, garage door, furnace controls, and water pump — shed these at 20% battery. Tier 3 (Convenience) includes TV, laundry, and dishwasher — turn off at 40% battery. Tier 4 (Deferred) includes EV charging, electric dryer, and whole-house AC — disconnect immediately when the outage begins unless you have 20+ kWh of capacity.

What is load shedding on a home battery system and how does it work?

Load shedding is the automated or manual process of disconnecting non-essential circuits to extend battery backup time during an outage. Smart panels like Span Panel, Schneider Pulse, and Lumin selectively turn off circuits based on battery state of charge. Tesla Powerwall 3 supports load shedding through its Backup Gateway and app-controlled circuit priorities. Enphase IQ Battery systems use the IQ System Controller to manage up to 12 essential circuits. FranklinWH aGate enables circuit-level priority settings through its mobile app.

How long can I run my refrigerator on battery backup during a power outage?

A standard refrigerator drawing 150-400W (1-2 kWh/day) can run for 24-48 hours on a 13.5 kWh Tesla Powerwall 3, consuming only 8-15% of total capacity per day. During a 72-hour outage, the refrigerator alone uses 3-6 kWh, leaving 7.5-10.5 kWh for other critical loads. For maximum efficiency, avoid opening the fridge unnecessarily during outages and ensure the refrigerator is on its own dedicated circuit in your critical loads panel.

Can I power my well pump on a home battery during an outage, and how much capacity does it use?

Yes, a ½ HP well pump drawing 1,000W start-up (surge) and 600-800W running can be powered by a 13.5+ kWh battery. A well pump uses approximately 0.5-1.0 kWh per day for a family of four. Wire the well pump to your critical loads panel as a Tier 2 (Essential) circuit. During a 24-hour outage, expect the well pump to cycle 4-6 times for 10 minutes each, consuming 0.4-0.8 kWh total. For homes in wildfire or hurricane zones, prioritize the well pump above all non-medical loads.

What battery capacity do I need for 24, 48, and 72 hours of outage backup?

For 24 hours of Tier 1 + Tier 2 backup (refrigerator, lights, internet, medical, furnace controls, well pump), you need 5-8 kWh of usable capacity. For 48 hours, budget 10-16 kWh. For 72 hours, plan for 15-24 kWh. A single Tesla Powerwall 3 (13.5 kWh) covers 36-48 hours of Tier 1+2 loads. FranklinWH aPower 2 (20 kWh) covers 60-72 hours. Adding a 5 kW solar array extends all durations by 2-3x during sunny weather, producing 15-25 kWh per day for recharging.

How do I configure load shedding on a Tesla Powerwall 3 during an outage?

In the Tesla app, navigate to Settings > Backup > Storm Watch to enable automatic weather-based preparation. During an active outage, use the Tesla app's Time-Based Control or Custom priority settings to manage which circuits stay active. The Tesla Powerwall 3 integrates with the Tesla Backup Gateway or supported smart panels (Span, Lumin) for circuit-level load shedding. Without a smart panel, you manually flip breakers on non-essential circuits in your critical loads subpanel. Set your Backup Reserve to at least 20% to preserve Tier 1 capacity for extended outages.

Should I run my heating or air conditioning on battery during a winter storm or hurricane outage?

Central HVAC (3,000-5,000W) will drain a 13.5 kWh battery in 2-4 hours and should be deferred unless you have 20+ kWh capacity. Instead, power a single high-efficiency mini-split heat pump (700-1,200W) as a Tier 3 circuit, which provides heating or cooling to one room for 8-12 hours on 13.5 kWh. For gas furnaces, only the blower motor and controls (300-500W) need battery power — the furnace itself runs on natural gas or propane. In winter storm scenarios, prioritize furnace blower and heating controls above all non-medical loads.

How much does it cost per hour to run each tier of home battery backup during an outage?

Based on the average U.S. electricity rate of $0.16/kWh, Tier 1 loads (refrigerator + lights + phone charging) cost approximately $0.03-0.05/hour in energy equivalent. Tier 2 (adding internet, furnace blower, well pump) raises it to $0.08-0.12/hour. Tier 3 (adding TV, dishwasher, laundry) costs $0.20-0.35/hour. Tier 4 (EV charging, electric dryer, whole-house AC) adds $0.50-1.20/hour. With solar recharging during daylight, effective costs drop to near $0 for Tier 1-2 loads during sunny multi-day outages.

Home Battery Circuit Priority Guide: What to Power First During a 24+ Hour Outage in 2026

Quick Answer

During a 24+ hour power outage, prioritize your home battery circuits in four tiers: Critical (refrigerator, medical devices, lighting), Essential (internet, furnace controls, well pump), Convenience (TV, laundry, dishwasher), and Deferred (EV charging, electric dryer, whole-house AC). A 13.5 kWh battery like the Tesla Powerwall 3 can sustain Tier 1 and Tier 2 loads for 36-48 hours when you actively shed Tier 3 and Tier 4 loads. With solar recharging, that extends to days or weeks. This guide provides exact wattage numbers, battery capacity budgets per tier, brand-specific load shedding setup instructions, and scenario-based strategies for winter storms, hurricanes, and wildfire PSPS events.

Key Takeaways

Tier 1 (Critical) loads consume only 0.5-2.0 kWh/day, meaning a 13.5 kWh battery can sustain them for 5-10 days without solar
A four-tier load shedding strategy extends backup time by 3-5x compared to running everything indiscriminately
Tesla Powerwall 3, Enphase IQ, and FranklinWH all support circuit-level load shedding through their respective gateways and mobile apps
A 5 kWh battery covers Tier 1 only for 24-48 hours; 13.5 kWh covers Tier 1+2 for 36-48 hours; 20+ kWh covers Tier 1-3 for 24-36 hours
Gas furnace blowers use only 300-500W vs. 3,000-5,000W for electric HVAC — prioritize gas heat during winter outages
Solar recharging adds 15-25 kWh/day during sunny weather, effectively making Tier 1-2 loads unlimited for multi-day outages

The Four-Tier Load Prioritization Framework

When the grid goes down, your battery becomes your only power source. Without a strategy, even a 20 kWh system can drain in hours. The key is knowing exactly what to power, what to shed, and when.

Tier 1: Critical Loads (Always On)

These circuits sustain life, prevent food spoilage, and maintain basic safety. They should remain powered until your battery drops below 5-10% state of charge.

Appliance	Running Wattage	Daily kWh	Circuit Priority
Refrigerator	150-400W	1.0-2.0	Tier 1
Chest freezer	100-250W	0.8-1.5	Tier 1
CPAP machine	30-60W	0.3-0.5	Tier 1
Oxygen concentrator	200-350W	4.8-8.4	Tier 1
LED lighting (6-8 fixtures)	60-120W	0.5-1.0	Tier 1
Phone/tablet charging	20-50W	0.2-0.4	Tier 1
Security system & cameras	30-80W	0.7-1.9	Tier 1
Smoke/CO detectors	5-15W	0.1-0.4	Tier 1

Total Tier 1 daily consumption: 2.5-6.0 kWh (depending on medical device usage)

A 13.5 kWh Tesla Powerwall 3 at 90% depth of discharge provides 12.15 kWh usable. At Tier 1 consumption rates, that’s 48-72 hours of pure battery backup for critical loads alone. A smaller 5 kWh battery (like the Enphase IQ Battery 5P) provides 18-24 hours of Tier 1 backup.

For households relying on medical devices, the oxygen concentrator dominates energy consumption at 4.8-8.4 kWh/day. In these cases, a 13.5 kWh battery covers 36-48 hours. If you depend on powered medical equipment, consider a dedicated medical device backup strategy and size your system for at least 48 hours of runtime.

Tier 2: Essential Loads (Shed at 20% Battery)

These circuits maintain habitability and communication. Keep them running through the middle phase of an outage, but be prepared to shed them if the battery drops below 20%.

Appliance	Running Wattage	Daily kWh	Notes
Internet router/modem	10-25W	0.24-0.6	Critical for communication
Furnace blower (gas)	300-500W	3.6-6.0 (heating season)	Gas heat, electric blower
Boiler circulator pump	50-150W	1.2-3.6	Hydronic heating systems
Well pump (½ HP)	600-1,000W	0.5-1.0	Intermittent duty cycle
Sump pump	800-1,200W	0.4-1.2	Intermittent, storm-critical
Garage door opener	350W	0.1-0.2	Brief cycles only
Microwave (occasional)	1,000-1,500W	0.3-0.5	Brief usage for meals
Kitchen outlets (small appliances)	100-300W	0.5-1.5	Coffee maker, toaster

Total Tier 2 daily consumption: 4.0-12.0 kWh (wide range depends on heating season and pump duty cycles)

When combined with Tier 1, total daily consumption reaches 6.5-18 kWh. A 13.5 kWh battery covers 18-36 hours of Tier 1+2 combined. A 20 kWh FranklinWH aPower 2 covers 30-48 hours. This is why active load shedding matters: dropping Tier 2 at the right moment can buy another 12-24 hours of Tier 1 runtime.

Homes with a well pump on battery backup should treat the pump as Tier 2 during non-storm outages but elevate it to Tier 1 during flood or wildfire scenarios where municipal water may also be compromised.

Tier 3: Convenience Loads (Shed at 40% Battery)

These loads improve comfort but aren’t necessary for health, safety, or basic habitation. Shed them early in any outage expected to exceed 12 hours.

Appliance	Running Wattage	Daily kWh	Notes
TV (55-65” LED)	80-150W	0.6-1.2	Entertainment
Gaming PC / desktop computer	200-500W	1.6-4.0	Work from home may elevate
Dishwasher	1,200-1,800W	1.0-1.5	Per cycle
Washing machine	350-500W	0.3-0.5	Per cycle
Mini-split heat pump (single room)	700-1,200W	5.6-9.6	Cooling/heating one room
Ceiling fans	15-90W each	0.4-2.2	Per fan, per day
Hair dryer	1,200-1,800W	0.2-0.3	Brief usage

Total Tier 3 daily consumption: 5.0-15 kWh (highly variable)

Tier 4: Deferred Loads (Disconnect Immediately)

These are the energy hogs. Unless you have 27+ kWh of battery capacity and active solar production, disconnect these circuits the moment an outage begins.

Appliance	Running Wattage	Daily kWh	Notes
Central AC (3-ton)	3,000-5,000W	24-40+	Biggest household load
Electric water heater	4,000-4,500W	8-12	Recovery takes 45-60 min
Electric dryer	4,500-5,500W	3.0-4.5	Per cycle
Electric oven/range	2,000-3,500W	2.0-4.0	Per hour of cooking
EV charger (Level 2)	7,200-11,500W	30-80+	Completely drains battery
Pool pump	1,100-2,200W	13-27	Non-essential during outage
Hot tub / spa heater	4,000-6,000W	48-72	Massive standby drain

Any single Tier 4 appliance can drain a 13.5 kWh battery in 1-4 hours.

Battery Capacity Budget by Tier

Here’s how different battery sizes perform across tier combinations:

5 kWh Battery (e.g., Enphase IQ Battery 5P)

Tier Combination	Runtime (No Solar)	Runtime (With 5 kW Solar)
Tier 1 only	18-24 hours	3-5 days
Tier 1 + 2	8-12 hours	1-2 days
Tier 1 + 2 + 3	4-6 hours	8-14 hours
All tiers	1-2 hours	3-5 hours

A 5 kWh battery is sufficient for short outages (4-8 hours) covering critical loads only. It is not recommended for extended outages without substantial solar production.

10 kWh Battery (e.g., 2× Enphase IQ Battery 5P)

Tier Combination	Runtime (No Solar)	Runtime (With 5 kW Solar)
Tier 1 only	36-48 hours	Unlimited (sunny days)
Tier 1 + 2	16-24 hours	2-3 days
Tier 1 + 2 + 3	8-12 hours	1-2 days
All tiers	2-3 hours	5-8 hours

13.5 kWh Battery (e.g., Tesla Powerwall 3)

Tier Combination	Runtime (No Solar)	Runtime (With 5 kW Solar)
Tier 1 only	48-72 hours	Unlimited (sunny days)
Tier 1 + 2	24-36 hours	3-5 days
Tier 1 + 2 + 3	12-18 hours	1-2 days
All tiers	3-4 hours	6-10 hours

20+ kWh Battery (e.g., FranklinWH aPower 2)

Tier Combination	Runtime (No Solar)	Runtime (With 6 kW Solar)
Tier 1 only	5-7 days	Unlimited
Tier 1 + 2	48-60 hours	Unlimited (sunny days)
Tier 1 + 2 + 3	24-36 hours	2-3 days
All tiers (incl. mini-split AC)	8-12 hours	1-2 days

Use our whole-home battery sizing calculator to determine the right capacity for your specific load profile.

Outage Duration Strategies

24-Hour Outage Strategy

A 24-hour outage is the most common type — caused by severe thunderstorms, equipment failure, or rolling blackouts. Most battery systems handle this comfortably.

If you have 13.5+ kWh:

Hours 0-12: Run Tier 1 + Tier 2 normally. Use microwave, internet, furnace blower as needed.
Hours 12-18: Shed Tier 3 if battery drops below 40%. Turn off TV, gaming PC, and dishwasher.
Hours 18-24: If battery falls below 20%, shed Tier 2 non-medical loads. Keep internet and furnace controls if possible.
Throughout: Avoid opening the refrigerator more than necessary. A closed fridge maintains safe temperature for 4 hours; a closed freezer for 48 hours.

If you have only 5-10 kWh:

Hours 0-6: Tier 1 + Tier 2 only.
Hours 6-12: Tier 1 + internet only.
Hours 12-24: Tier 1 only. Shed everything else.
If solar is available: recharge during peak sun hours (10 AM - 3 PM) and resume Tier 2 loads.

48-Hour Outage Strategy

A 48-hour outage typically follows a major storm (ice storm, derechos, tropical storm). Power infrastructure damage takes time to repair.

If you have 13.5+ kWh with solar:

Daytime (both days): Run all Tier 1 + Tier 2 loads. Solar recharges battery to 90-100% by sunset.
Nighttime (both nights): Drop to Tier 1 + internet only. If winter, keep furnace blower running.
Critical decision: At sunset on Day 1, check battery level. If below 60%, shed Tier 2 immediately. If above 80%, you can keep Tier 2 through the night.
Solar boost: A 5 kW array produces 15-25 kWh on a sunny day — more than enough to fully recharge and run daytime loads simultaneously.

If you have 13.5 kWh without solar:

This is a stretch scenario. You must aggressively shed loads from Hour 0.
Hours 0-24: Tier 1 + internet only. Minimal Tier 2 usage (furnace on low, well pump for essential water only).
Hours 24-48: Tier 1 only. If battery drops below 10%, even shed non-medical Tier 1 and focus exclusively on refrigerator + medical devices.
Without solar, a 13.5 kWh battery cannot sustain 48 hours of Tier 1+2. Plan for a backup generator hybrid system if your area experiences frequent 48+ hour outages.

72+ Hour Outage Strategy

72+ hour outages occur during major events: hurricanes (Helene, Milton), ice storms (2021 Texas freeze), or wildfire PSPS shutoffs (California). These scenarios demand aggressive conservation and ideally solar recharging.

Minimum recommended: 20+ kWh battery + 5 kW solar

Daylight hours: Run Tier 1 + Tier 2 + limited Tier 3 (one mini-split, TV, limited laundry). Solar covers loads and recharges battery.
Night: Tier 1 + essential Tier 2 (furnace/well pump as needed).
Storm watch: Enable Storm Watch or similar pre-charge features 24-48 hours before forecasted events to ensure battery starts at 100%.
Conserve water: Well pump duty cycles consume 0.5-1.0 kWh/day — switch to bottled water for drinking and minimize showers.
Rotate loads: If you need to run the microwave (1,500W for 5 minutes = 0.125 kWh), briefly turn off the mini-split or other high-wattage loads to stay within inverter limits.

Set your battery reserve percentage to at least 20-25% during multi-day outages to maintain a safety buffer for unexpected Tier 1 needs.

Configuring Load Shedding on Popular Systems

Tesla Powerwall 3

The Tesla Powerwall 3 pairs with the Tesla Backup Gateway 2 or a compatible smart panel for circuit-level control.

App-based priority setup:

Open the Tesla app → Settings → Backup
Enable Storm Watch — automatically charges battery to 100% when severe weather is forecast
Set Backup Reserve to 20% minimum (ensures Tier 1 capacity is preserved)
If using a Span Smart Panel integration: assign each circuit a priority (1-4) in the Span app
During an outage, the Tesla app shows real-time energy flow — manually turn off circuits via smart breakers or your critical loads panel

Without a smart panel: Tesla Powerwall 3 backs up everything on the critical loads subpanel. To shed loads, manually flip breakers off in the subpanel. The Powerwall app doesn’t support per-circuit control without third-party panel integration.

Time-Based Control: If you have solar + TOU rates, Time-Based Control can be repurposed during outages — it prioritizes battery usage patterns that extend runtime. However, this feature is designed for cost optimization, not outage management. Switch to Backup mode during active outages.

Enphase IQ Battery (IQ 10T / IQ 15)

Enphase pairs the IQ Battery with the IQ System Controller 2 (or 3G), which includes up to 12 load-shedding circuits.

Configuration steps:

Open the Enphase app (Enlighten) → System → IQ System Controller
Navigate to Load Management → Essential Loads
Assign each circuit a priority: Critical, High, Medium, Low
Set automatic load shedding rules: “Shed Low priority circuits at 40% SoC” and “Shed Medium at 20% SoC”
The IQ System Controller’s built-in transfer switch detects outages in <20ms and automatically isolates the Essential Loads panel

Microinverter advantage: Enphase’s IQ8 microinverters allow each solar panel to operate independently. During an outage, even partial shading (one panel in sun) can provide trickle charging to the battery, extending runtime during overcast conditions.

FranklinWH aPower 2 + aGate

FranklinWH offers the most granular native load shedding without requiring a third-party smart panel.

Configuration via FranklinWH app:

Open the FranklinWH app → aGate → Circuit Priority
Assign each of the aGate’s 16 controllable circuits to a tier (1-4)
Set SoC thresholds: “Tier 4 off immediately, Tier 3 off at 50%, Tier 2 off at 25%, Tier 1 stays on”
Enable Storm Guard — pre-charges to 100% when severe weather alerts are issued
The aGate supports both automatic and manual load shedding — automatic rules execute without app intervention

FranklinWH advantage: The aGate includes built-in load shedding for up to 16 circuits natively — no Span Panel or Lumin subpanel needed. This makes it the most cost-effective option for homeowners who want circuit-level outage management without additional hardware.

Smart Panel Integrations

For any battery system, third-party smart panels add circuit-level control:

Smart Panel	Compatible Batteries	Cost (Installed)	Circuits
Span Panel	Tesla Powerwall, SolarEdge	$3,500-$5,000	32
Schneider Pulse	Tesla, FranklinWH, Custom	$3,000-$4,500	Up to 22
Lumin Panel	Any battery with CT clamps	$2,500-$4,000	Up to 14
Savant Power	Various	$4,000-$7,000	Up to 32

A smart panel transforms your critical loads panel into an intelligent, app-controllable system. During an outage, you can shed circuits remotely instead of flipping breakers in the dark.

Real-World Outage Scenarios

Scenario 1: Winter Ice Storm (Texas 2021-style)

Conditions: Sub-freezing temperatures, 36-72 hour outage, overcast skies reducing solar output by 60-80%.

Priorities:

Gas furnace blower (300-500W) — elevate to Tier 1 to prevent pipe freezing
Refrigerator + freezer (200-400W)
Well pump or water heater recirculator (prevent frozen pipes)
Internet + phones (emergency communication)
LED lighting

Strategy: A 13.5 kWh battery without solar lasts 24-30 hours in this scenario because the furnace blower runs nearly continuously in sub-freezing temps. If you have gas heat, the battery only powers the blower and controls — not the actual heating element. This dramatically extends runtime vs. homes with electric resistance heating (which draws 15,000-25,000W and cannot be backed up by any standard battery).

Cost per hour: Tier 1+2 during a winter storm = approximately 1.5-2.5 kWh/hour = $0.24-$0.40/hour at $0.16/kWh.

Key risk: Frozen pipes cause $5,000-$15,000 in damage. Prioritizing furnace blower and well pump over lighting and electronics prevents this catastrophic loss.

Scenario 2: Summer Hurricane (Helene/Milton 2024-style)

Conditions: 48-96 hour outage, 85-95°F temperatures, potential for solar production during clear skies after storm passage.

Priorities:

Refrigerator + freezer (food safety, 200-400W)
Sump pump (flooding prevention, 800-1,200W intermittent)
Medical devices (CPAP, oxygen)
Internet + phones (emergency alerts)
One mini-split AC unit for a single cooling room (700-1,200W)

Strategy: After a hurricane, solar production can recover quickly once skies clear — a 6 kW array may produce 15-20 kWh/day starting Day 2. Use Day 1 (during the storm) for Tier 1 + sump pump only. Once skies clear, resume Tier 2 and limited Tier 3 (one mini-split cooling room).

Food safety math: A refrigerator stays below 40°F for 4 hours unopened. A full freezer holds temperature for 48 hours. Prioritize freezer over fridge — the freezer’s larger thermal mass means it cycles less, consuming less energy.

Cost per hour: Tier 1+2 during a hurricane with sump pump cycling = 0.8-1.5 kWh/hour = $0.13-$0.24/hour.

Scenario 3: Wildfire PSPS (California)

Conditions: Pre-planned utility shutoff lasting 24-72 hours, typically during hot, dry, windy conditions. Advance notice of 12-48 hours provided.

Priorities:

Medical devices
Refrigerator + freezer
Well pump or water storage (fire suppression reserve)
Internet + phones (evacuation alerts)
Whole-house fan or mini-split for smoke filtration

Strategy: PSPS events offer advance warning — use it. Set Storm Watch / Storm Guard 24 hours before the shutoff to ensure 100% charge. During a PSPS, solar typically works well (clear, sunny conditions), so a 6 kW array can sustain Tier 1-2 indefinitely.

Unique consideration: Maintain a reserve for potential evacuation — keep at least 30% battery charge for EV emergency charging or medical device transport. Set your backup reserve to 30% during fire season.

Cost per hour: Tier 1+2 during PSPS with solar = effectively $0/hour during sunny days, $0.10-$0.15/hour overnight.

Cost of Running Each Tier Per Hour

Understanding the hourly energy cost of each tier helps you budget your battery capacity during extended outages:

Tier	Typical Load Range	kWh/Hour	Cost/Hour ($0.16/kWh)	13.5 kWh Battery Drain Time
Tier 1 (Critical)	200-500W	0.2-0.5	$0.03-$0.08	24-48 hours
Tier 1+2 (Essential)	500-1,500W	0.5-1.5	$0.08-$0.24	8-18 hours
Tier 1+2+3 (Convenience)	1,200-3,000W	1.2-3.0	$0.19-$0.48	4-8 hours
All Tiers (Whole Home)	3,000-8,000W+	3.0-8.0+	$0.48-$1.28+	1.5-3 hours

The takeaway: Adding Tier 3 and Tier 4 loads during an outage cuts your backup time by 60-80%. A disciplined tier-based approach gives you 3-5x more runtime from the same battery.

Setting Up Your Critical Loads Panel for Tier-Based Prioritization

Your critical loads panel is the physical foundation of your outage strategy. Here’s how to map tiers to circuits:

Recommended panel layout (60A, 16-space subpanel):

Breakers 1-2: Refrigerator / Freezer (Tier 1)
Breaker 3: Medical devices / CPAP (Tier 1)
Breaker 4: Kitchen lighting + bedroom lighting (Tier 1)
Breaker 5: Phone charging outlets (Tier 1)
Breaker 6: Security system + smoke detectors (Tier 1)
Breaker 7: Internet router/modem (Tier 2)
Breaker 8: Furnace blower / boiler controls (Tier 2)
Breaker 9: Well pump (Tier 2)
Breaker 10: Sump pump (Tier 2)
Breaker 11: Garage door opener (Tier 2)
Breaker 12: Microwave + kitchen outlets (Tier 2)
Breaker 13: Mini-split heat pump (Tier 3)
Breaker 14: TV / entertainment outlets (Tier 3)
Breaker 15: Laundry room (Tier 3)
Breaker 16: Spare (future expansion)

Color-code your breakers by tier (red = Tier 1, yellow = Tier 2, blue = Tier 3, uncolored = Tier 4). During an outage, shed from the bottom up: flip off Tier 4 (if present), then Tier 3, then Tier 2 as battery drains.

Maximizing Battery Runtime During Extended Outages

Quick Wins (Saves 0.5-2.0 kWh/day)

Lower refrigerator thermostat from 37°F to 40°F — reduces compressor cycles by 15-20%
Switch chest freezer to “super freeze” before the outage (if advance notice) — builds thermal mass
Unsubscribe phantom loads — smart TVs, game consoles, and cable boxes draw 5-30W each in standby
Use LED flashlights and lanterns instead of leaving room lights on
Charge phones during peak solar hours (10 AM - 3 PM), not at night
Batch microwave usage — heat multiple items in one session rather than reheating throughout the day

Advanced Strategies (Saves 2-5 kWh/day)

Install a DC-coupled solar battery system — eliminates inverter losses (5-8% efficiency gain) for solar-to-battery charging
Use a 12V DC refrigerator as a backup — draws only 40-60W vs. 150-400W for AC models
Replace electric water heating with a heat pump water heater — cuts water heating energy by 60-70% (relevant for pre-outage planning)
Install low-flow showerheads — reduces well pump duty cycles during outages
Pre-cool or pre-heat your home before a forecasted outage — thermal mass keeps the house comfortable for 4-8 hours without HVAC

Summary: Your Outage Action Plan

When the power goes out, follow this sequence:

First 5 minutes: Check Tesla/FranklinWH/Enphase app for outage confirmation and battery state of charge
First hour: Manually shed all Tier 4 loads. Enable Storm Watch / outage mode in your app.
Hour 1-6: Run Tier 1 + Tier 2 normally. Monitor battery drain rate in the app.
If outage expected >12 hours: Shed Tier 3 at 50% SoC. Reduce refrigerator openings.
If outage expected >24 hours: Shed Tier 2 at 25% SoC (except medical and internet). Switch to survival mode.
If battery drops below 10%: Tier 1 only. Prepare for manual shutdown if below 5%.

With a properly configured critical loads panel and a tier-based strategy, a 13.5 kWh battery can keep your essential systems running for 24-48 hours — or indefinitely with solar. The difference between running out of power at hour 8 and hour 36 is entirely about which circuits you choose to power.

FAQ

Ready to calculate your exact backup time? Use our Home Battery Backup Time Calculator to input your specific appliances, battery size, and solar production for a customized outage plan. Then check our whole-home battery sizing calculator to verify your system can handle your tier-based strategy.

Already have a battery system? Make sure your critical loads panel is properly configured for tier-based load shedding, and review your optimal reserve percentage setting before the next storm season.

Use our free Solar Battery Payback Calculator to estimate your total savings and payback period for a home battery system with solar.