FranklinWH aPower 2 Review: Whole-Home Backup and Generator Integration

The FranklinWH aPower 2 is a 15 kWh AC-coupled home battery that pairs with FranklinWH’s aGate, a smart switch that manages grid, solar, battery and generator. This review uses FranklinWH’s datasheet and installation guides. We haven’t tested one ourselves, so there are no hands-on runtime claims here.

FranklinWH aPower 2 Specs

Spec	Value
Usable energy	15 kWh (AC) per unit
Continuous discharge	10 kW / 11.5 kVA
Peak output	15 kW for 10 s
Continuous charge	8 kW
Configurable output	10, 9.6, 7.6 or 5 kW (set at commissioning)
Scalability	Up to 15 units (225 kWh) per aGate
Coupling	AC-coupled
Grid	120/240V or 120/208V, 60 Hz
Round-trip efficiency	90% (grid-battery-load)
Chemistry	LFP
Weight	357 lb complete
Warranty	15 years, 60 MWh aggregate throughput (per datasheet)

How much does the FranklinWH aPower 2 weigh?

357 lb complete per unit, per FranklinWH’s datasheet.

Can I add more aPower 2 units later?

Yes. FranklinWH supports up to 15 units per aGate. Your installer confirms the electrical design for the final size.

What size generator do I need with FranklinWH?

FranklinWH recommends about 12 kW of generator for one aPower 2 and about 23 kW for two, connected through the aGate’s generator module.

Does the aPower 2 work with Enphase or SolarEdge solar?

It’s AC-coupled, so it connects on the AC side alongside most grid-tie inverters. Your installer confirms compatibility and any settings needed.

Can the aPower 2 be installed outdoors?

Check FranklinWH’s installation guide for the enclosure rating and allowed locations. Placement also has to follow NEC Article 706, NFPA 855 and local fire codes.

Source: FranklinWH aPower 2 datasheet and system installation guide; FranklinWH end-user warranty. Accessed Oct 2026.

FranklinWH aPower 2 Generator Integration

With an optional generator module, the aGate can start and stop a standby or portable 240V generator automatically, run home loads from it and recharge the batteries. FranklinWH recommends about 12 kW of generator for one aPower 2 and about 23 kW for two. It supports one generator source at a time.

This is the main reason to pick FranklinWH for long outages. The generator runs only when needed, and the battery covers the quiet hours.

What We Like

• Big 15 kWh blocks, so fewer units for whole-home backup
• Strong continuous power at 10 kW per unit
• Generator control built into the aGate ecosystem
• AC-coupled, so it works alongside most existing solar

Things to Know

• Heavy: 357 lb per unit, floor or wall mounted
• aGate version matters: on aGate X 1.3, output is capped at 9.6 kW unless a combiner box is added (installation guide)
• Installer-only, and prices vary. We don’t publish one we can’t verify
• No 25D credit for homeowner-owned systems installed after 2025

See aPower 2 on FranklinWH’s website.

How It Compares

Per unit, the aPower 2 holds more energy than a Powerwall 3 (15 vs 13.5 kWh) and slightly less continuous power (10 vs 11.5 kW). Unlike Powerwall 3, it has no built-in solar inverter, so new solar needs its own inverter. Its edge is the generator control in the aGate.

Who It’s For

Homes that get long outages, already own or plan a generator, and want whole-home backup with fewer, bigger batteries.

Worked Example: Sizing a FranklinWH System

Using FranklinWH’s per-unit figures (15 kWh usable, 10 kW continuous, 15 kW peak for 10 seconds, up to 15 units per aGate):

Units	Usable energy	Continuous power	Runtime at 1.5 kW average	Runtime at 3 kW average
1	15 kWh	10 kW	about 10 h	about 5 h
2	30 kWh	20 kW	about 20 h	about 10 h
3	45 kWh	30 kW	about 30 h	about 15 h

Runtimes are energy ÷ load with no solar or generator recharge, before losses. Final system power can be limited by the aGate version and its configuration, as noted above. To size your own home, see how many batteries to power a house.

Worked Example: Battery Plus Generator in a Long Outage

Here is how generator integration can work over a cloudy three-day outage for a home averaging 1.5 kW (36 kWh a day) with one aPower 2 and a 12 kW generator, FranklinWH’s recommended size for one unit (illustrative):

1. Hours 0–10: the battery covers the home silently (15 kWh ÷ 1.5 kW).
2. Hour 10: the battery reaches its low set point, and the aGate starts the generator.
3. Generator run: the generator powers the home and recharges the battery at up to the aPower 2’s 8 kW continuous charge rate. A full recharge of about 15 kWh takes roughly 2 hours at 8 kW, before losses.
4. Generator off: the battery takes over again for about another 10 hours.

In this pattern the generator runs about 2 to 3 hours in every 12 or so, rather than all day. That saves fuel and noise. Actual behavior depends on the settings and loads. Compare options in generator vs battery backup for home.

Round-Trip Efficiency in Practice

FranklinWH lists 90% round-trip efficiency (grid to battery to load). That means:

• Put 10 kWh in, get about 9 kWh out.
• Under net billing with an $0.08 export credit and a $0.40 evening rate (illustrative), each 10 kWh shifted is worth 9 × $0.40 − 10 × $0.08 = $2.80.
• One aPower 2 cycling 15 kWh a day under those rates would be worth about $4.20 a day, or roughly $1,530 a year.

See is a solar battery worth it for how rate structures change that number.

Warranty Math

FranklinWH’s datasheet lists a 15-year warranty with 60 MWh of aggregate throughput, and its end-user warranty sets 70% capacity retention. At one full 15 kWh cycle a day, 60 MWh ÷ 15 kWh = 4,000 cycles, or about 11 years. A home that cycles about half the battery daily would reach 15 years first. Compare brands in home battery warranties compared.

How the System Fits Together

• aPower 2 units: the batteries, each with its own inverter (AC-coupled).
• aGate: the smart switch that connects grid, solar, battery, generator and home loads, and isolates the home in an outage.
• Generator module (optional): lets the aGate start and stop a 240 V generator.
• Existing or new solar: any compatible grid-tie inverter on the AC side.
• Backup panel (optional): for partial-home setups. See critical loads panel explained.

Step-by-Step: Planning an aPower 2 Install

1. Total your daily kWh and peak loads, including AC starting.
2. Choose whole-home or partial-home backup.
3. Pick units: kWh needed ÷ 15, and check that units × 10 kW covers peak loads.
4. If using a generator, confirm its size against FranklinWH’s guidance (about 12 kW for one aPower 2, about 23 kW for two).
5. Plan floor or wall space for 357 lb per unit.
6. Get quotes from FranklinWH-certified installers, and compare them with the options in Powerwall 3 vs Enphase vs FranklinWH.

FAQ

How long will one aPower 2 run a house?

Example math: 15 kWh ÷ a 1.5 kW average ≈ 10 hours, before solar or generator recharge.

Can it charge from a portable generator?

Yes, a 240V generator through the generator module. Follow FranklinWH’s sizing guidance.

Does it work with my existing solar?

It’s AC-coupled, so usually yes. Your installer confirms compatibility.

Sources: FranklinWH, aPower 2 Datasheet; Generator Integration and Best Practices; System Installation Guide (aGate 1.3 / 1.3.1 & aPower 2). Accessed Oct 2026.

Related: EcoFlow Delta 3 Max vs Generator, EcoFlow Delta 3 Max for Home Backup