POWER GEAR GUIDE · HOME BACKUP SYSTEMS

Best Whole-House Battery Backup Systems: Compare Tesla, Enphase & FranklinWH

Compare professionally installed 120/240V home batteries, understand what “whole-house backup” really means, and find the system architecture that fits your home's electrical loads, solar setup and outage needs.

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Whole-house battery backup systems buying guide

Affiliate disclosure: As an Amazon Associate, Power Gear Guide earns from qualifying purchases. We may receive a commission through qualifying shopping links at no additional cost to you. Shopping buttons open Amazon search results, which may include accessories or alternatives rather than the exact installed system discussed.

A whole-house battery is not simply a large portable power station. It is an installed electrical system designed around your service panel, selected backup circuits, inverter output, transfer equipment and available energy storage. The battery brand matters, but a properly designed installation matters just as much.

Quick Answer: Which Whole-House Battery System Is Best?

Tesla Powerwall 3 is our leading starting point for a new integrated solar-and-backup project. It combines 13.5kWh of nominal AC battery energy with configurable continuous AC output up to 11.5kW in the U.S. Its integrated solar-inverter architecture can simplify some new system designs, although the best configuration depends on your electrical service, solar equipment and installer.

Enphase IQ Battery 5P is particularly relevant for compatible Enphase solar systems and modular AC-coupled installations. FranklinWH aPower 2 deserves serious consideration when you want a 15kWh AC-coupled battery with strong continuous output and the manufacturer's aGate-based home energy management ecosystem.

Important: None of these products automatically guarantees that every circuit in every house will run during an outage. Whole-house capability is a property of the complete installed design—not the battery's marketing label.

Top Whole-House Battery Backup Systems

These are three distinct approaches to installed home storage. They are not ranked by unverified installed prices or fabricated performance tests. The recommendations reflect published manufacturer specifications, electrical architecture and likely project fit.

Best integrated starting point

Tesla Powerwall 3

Strong candidate for new solar-plus-storage projects that benefit from a combined battery and solar-inverter platform.

Battery energy13.5kWh
AC outputUp to 11.5kW

Watch for: site-specific output settings, compatible expansion equipment, solar architecture and installation costs.

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Best modular AC-coupled option

Enphase IQ Battery 5P

Modular 5kWh batteries with embedded microinverters, especially relevant to compatible Enphase solar installations.

Usable energy5.0kWh/unit
Rated AC output3.84kVA/unit

Watch for: number of batteries required, System Controller configuration and differences between backup-capable and grid-tied-only designs.

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Best high-capacity AC-coupled alternative

FranklinWH aPower 2

A 15kWh installed battery platform with substantial output and integration through FranklinWH's home energy management equipment.

Usable energy15kWh/unit
AC output10kW/unit

Watch for: aGate requirements, generator and solar compatibility, and the total installed system design.

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Shopping searches do not establish that these professionally installed systems are available for direct purchase on Amazon. Check the exact product and seller before purchasing; installation is generally a separate service.

Tesla vs. Enphase vs. FranklinWH: Key Specifications

System Energy per battery Continuous AC output Architecture Best starting use case
Tesla Powerwall 3 13.5kWh nominal AC Configurable 5.8–11.5kW Integrated solar inverter and battery New integrated solar and backup projects
Enphase IQ Battery 5P 5.0kWh usable 3.84kVA at 240V AC-coupled, embedded microinverters Compatible Enphase and modular retrofits
FranklinWH aPower 2 15kWh usable AC 10kW real power; 11.5kVA apparent power AC-coupled, paired with system controls High-capacity backup with flexible system design

These figures are from manufacturer documentation. Tesla's maximum output is configurable and may be limited by installation or utility requirements. Enphase specifies apparent power in kVA; real-power delivery depends on operating power factor. FranklinWH distinguishes 10kW real power from 11.5kVA apparent power. Do not treat kW and kVA as interchangeable in every application.

Critical distinction: A battery's kWh rating determines how much energy it stores. Its kW rating determines how much real power it can deliver at once. A house can need more of either one independently.

Tesla Powerwall 3: Best for an Integrated Solar-and-Backup Project

Why Powerwall 3 Leads Our Shortlist

Tesla Powerwall 3 combines battery storage, a solar inverter and backup capability in one installed ecosystem. Tesla's U.S. technical documentation specifies 13.5kWh nominal AC battery energy and selectable nominal AC output ratings of 5.8kW, 7.6kW, 10kW or 11.5kW, subject to configuration.

That is a compelling combination for households planning a new solar installation alongside backup storage. However, a battery capable of 11.5kW is not automatically an 11.5kW installation: installer settings, interconnection rules, panel design and supported loads all matter.

Advantages
  • Substantial energy capacity in one unit.
  • High configurable AC output.
  • Integrated solar-inverter architecture.
  • Dedicated Powerwall 3 expansion batteries.
  • Manufacturer documentation for backup and system design.
Limitations
  • Professional electrical installation is essential.
  • Actual available output can be configured below the maximum.
  • Expansion adds energy, not automatically inverter power.
  • Existing solar and older Powerwall systems require compatibility review.
  • Final project cost depends on substantial site-specific work.

Expansion matters: Tesla's Powerwall 3 Expansion provides another 13.5kWh of battery energy, but it does not independently increase inverter output. An additional full Powerwall 3 and an expansion-only battery are different purchases.

Best for: homeowners comparing complete new solar-plus-storage proposals and wanting a relatively integrated architecture.

Not necessarily best for: homeowners whose existing solar hardware or backup requirements make a different AC-coupled platform simpler to integrate.

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Enphase IQ Battery 5P: Best for Modular AC-Coupled Storage

Why Enphase Makes Sense for the Right Solar Home

The North American IQ Battery 5P is a 5.0kWh usable AC-coupled battery with six embedded grid-forming microinverters and a 3.84kVA continuous output rating at 240V. Its smaller module size makes it easier to build a system in increments rather than purchasing all the storage capacity in one large unit.

Enphase is particularly relevant when the home's existing or planned solar architecture is compatible with the Enphase ecosystem. But battery installation alone does not guarantee backup: the correct system controller and overall backup design are essential.

Advantages
  • Modular 5kWh increments.
  • AC-coupled architecture.
  • Integrated battery microinverters.
  • Well-defined manufacturer specifications.
  • Potentially practical for compatible solar retrofits.
Limitations
  • One 5kWh battery may provide insufficient runtime for a whole house.
  • Multiple units are often needed for higher simultaneous loads.
  • Backup capability depends on compatible system components.
  • Grid-tied-only configurations should not be confused with backup installations.
  • Project economics depend on the total number of units and installation work.

Useful sizing example: Three IQ Battery 5P units provide 15kWh of published usable battery capacity. That is a storage comparison, not a promise of a particular household runtime or a guarantee that every load will be supported.

Best for: homeowners who want modular storage and have a compatible Enphase system or installer-supported design.

Not necessarily best for: buyers seeking a large amount of energy from a single battery cabinet.

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FranklinWH aPower 2: Best High-Capacity AC-Coupled Alternative

Why aPower 2 Belongs on the Shortlist

FranklinWH's aPower 2 is a different product generation from the earlier aPower system referenced in older buying guides. The manufacturer's aPower 2 datasheet specifies 15kWh usable AC energy per unit, 10kW maximum continuous real-power discharge, and 11.5kVA apparent power. It is an AC-coupled platform designed to operate within the broader FranklinWH home energy system.

That combination makes it a credible alternative for projects that prioritize relatively large storage modules and substantial inverter output, particularly where the installer can design the solar, grid and optional generator interfaces around the FranklinWH controls.

Advantages
  • 15kWh usable energy per unit.
  • 10kW continuous real-power output.
  • AC-coupled design.
  • Manufacturer-documented scalable architecture.
  • Potential integration with broader home-energy equipment.
Limitations
  • Requires a properly designed installed system.
  • Compatible aGate and other components affect the final configuration.
  • Generator support is conditional on equipment and installation design.
  • 10kW and 11.5kVA are not identical output claims.
  • Installer availability and total project cost require local quotations.

Best for: homeowners seeking a high-capacity AC-coupled battery with an installer-supported home energy management platform.

Not necessarily best for: buyers wanting a small plug-and-play battery or a solution that avoids professional installation.

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How Much Battery Storage Does a Whole House Actually Need?

Start with a load study, not a product name. An electrician or qualified installer should identify the circuits you want to back up, the expected running and starting power of connected equipment, and the energy needed over your target outage duration.

Power: Can it run the loads? Add simultaneous running watts, then check startup demands from air conditioning, pumps and other motors. A high kWh capacity does not compensate for insufficient inverter output.
Energy: For how long? Estimate total daily consumption in kWh for the selected circuits. Compare that figure with the battery's available stored energy and your reserve settings.
120V and 240V circuits Central air conditioning, electric dryers, ranges and well pumps may need 240V power and substantial starting current. Verify the actual backup panel and system design.
Solar recharge during an outage Solar panels do not guarantee continuous recharge. Weather, inverter design, solar capacity and battery state all affect how much energy is available.

Illustrative Battery Runtime: 13.5kWh vs. 15kWh

The following calculation assumes the specified battery energy is available for planning, with an additional illustrative 10% reserve and system-loss allowance. This is not a measured efficiency result for any product.

Battery energy 500W average load 1,000W average load 2,000W average load
13.5kWh About 24.3 hours About 12.2 hours About 6.1 hours
15kWh About 27 hours About 13.5 hours About 6.8 hours

Formula: estimated hours = battery energy in Wh × 0.90 ÷ average load in W. Actual usable energy and losses depend on the specific system, reserve settings, temperature, equipment and operating conditions. Household loads vary over time; these examples assume a constant average draw and no solar replenishment.

Example: air conditioning changes everything.

If a home averages 500W while running essential circuits, 13.5kWh may support roughly a day under the assumptions above. If air conditioning and other appliances raise the average to 2,000W, the same battery lasts only about six hours. The battery has not changed—the load has.

For more detailed estimates, use the Power Runtime Calculator. Its results should support, not replace, a site-specific electrical load study.

What Separates a Real Whole-House System From a Large Battery?

Installed home backup requires more than sufficient storage. The complete system must safely isolate from the utility during an outage, supply the intended circuits, manage solar generation when applicable, and comply with local electrical requirements.

Automatic transfer and isolation Verify which listed gateway, controller or transfer equipment is included. The system must prevent unsafe utility backfeeding.
Electrical panel and service limits Check panel configuration, service capacity, available breaker space and whether a dedicated backup loads panel is needed.
Large appliance management Ask whether the system can start and sustain HVAC, pumps, ovens and other large loads simultaneously—or whether load shedding is required.
Solar and generator compatibility Ask for a wiring diagram showing the exact existing or planned equipment. Do not assume every battery can operate with every solar inverter or generator.
Permits and utility approval Obtain a proposal that addresses local permits, inspection, interconnection and any applicable utility requirements.
Service and long-term support Compare warranty terms, covered equipment, battery throughput or retention limits, labor exclusions and installer support.

For an existing solar home, ask installers to explain whether they propose an AC-coupled retrofit or a redesign using a different inverter architecture. The cheapest-looking battery hardware may not produce the lowest total installed project cost.

How to Compare Installer Quotes Without Being Misled

Two proposals with the same nominal battery capacity can provide very different backup experiences. Ask every installer to quote against the same list of required circuits and the same outage-duration target.

What to request Why it matters What a useful answer includes
Backup circuit schedule Defines what actually runs during an outage Named circuits, loads and exclusions
System energy and output Separates runtime from simultaneous power Usable kWh, continuous kW, startup limitations
One-line electrical diagram Shows integration with the house Battery, inverter, gateway, panel and utility connections
Solar outage behavior Determines whether daytime charging is available Supported operating modes and equipment compatibility
Itemized installed cost Reveals hidden scope differences Equipment, labor, permits, electrical upgrades and exclusions
Warranty and service Clarifies long-term ownership obligations Manufacturer terms, installer labor coverage and support process

Practical recommendation: Obtain multiple site-specific proposals and compare them on the same electrical requirements. Do not select a winner based on a generic online installed-price estimate or battery cost per kWh alone.

Which System Should You Choose?

Building a new solar-plus-backup system? Start with Tesla Powerwall 3 and compare an integrated design against installer-proposed alternatives.
Already using compatible Enphase solar? Request an Enphase IQ Battery 5P proposal that specifies backup controller requirements and the number of units.
Want larger AC-coupled battery modules? Include FranklinWH aPower 2 and ask for the complete aGate-based system design.
Only need a few essential appliances? Compare critical-load backup proposals before paying for a whole-house architecture. A smaller solution may fit the actual need better.

To browse current battery-related shopping results, use the model-specific comparison buttons above. Amazon may not carry the complete installed systems or installation services.

Frequently Asked Questions

Can one battery back up an entire house?

Sometimes, but it depends on the home's simultaneous electrical demand, appliance startup requirements, the battery's inverter rating and how the electrical system is configured. A single unit may support all connected circuits while still requiring load management.

Is 13.5kWh enough for whole-house backup?

It may be sufficient for essential loads or a carefully managed home for a limited time. It is unlikely to provide extended operation of multiple energy-intensive appliances without solar replenishment or additional storage. Calculate the household's actual kWh consumption.

Does a home battery work during a power outage if I have solar panels?

Only when the solar, battery, inverter and backup control equipment are configured to operate safely while the grid is down. A standard grid-tied solar system may shut off during outages. Confirm the installed system's specific backup behavior.

What is the difference between whole-house and critical-load backup?

Whole-house designs are intended to supply the home's broader electrical system, subject to output and load-management limits. Critical-load systems supply selected circuits such as refrigeration, lighting, internet and essential outlets. Critical-load designs can be simpler and require less stored energy.

Is Tesla Powerwall 3 better than Enphase IQ Battery 5P?

They suit different architectures. Powerwall 3 offers larger energy capacity and higher maximum output per main unit, with an integrated solar inverter. IQ Battery 5P offers modular AC-coupled storage and may be attractive for compatible Enphase installations. The better purchase depends on the full installed proposal.

Can I install a whole-house battery myself?

These systems require appropriate electrical design, permitted installation, utility isolation and manufacturer-specified commissioning. Use qualified professionals and follow applicable local requirements rather than attempting an improvised connection to household wiring.

Will a home battery provide uninterrupted power to medical equipment?

Do not assume so. Backup transfer behavior, equipment compatibility, reserve settings and failure modes vary. Anyone relying on life-sustaining equipment should coordinate an appropriate backup plan with the equipment provider and relevant medical professionals.

Sources and Editorial Methodology

Power Gear Guide compared manufacturer-documented specifications, architecture, scalability and real-world installation considerations. These are research-based recommendations, not firsthand performance tests. No installed-price, battery-efficiency or warranty-service ranking is claimed.

Manufacturer specifications and configurations should be reconfirmed before purchase. Research-source links are informational; all shopping buttons in this article use Amazon affiliate searches.

Editorial note: Power Gear Guide evaluates documented specifications and buyer suitability. Actual whole-house backup capability must be established through a qualified, site-specific electrical design. No product was represented as personally tested, and no particular installed price or savings was assumed.

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