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15 kWh of usable storage, 10 kW continuous output, and the smartest energy management controller on the market. We break down the real-world performance, pricing, and whether the premium cost is justified in 2026 without the federal tax credit.
15 kWh
Capacity
10 kW
Continuous
15 kW
Peak Power
$17,500
Price
The FranklinWH aPower 2 is the best whole-home backup battery in 2026. At 15 kWh with 10 kW continuous output, a single unit backs up an entire house including central AC and EV charging, something no other single battery can match. The aGate controller is the smartest energy management hub available, with circuit-level control and seamless generator integration. The catch: $17,500 installed is premium pricing, and 89% efficiency trails competitors. ConnectedSolutions participants in MA, CT, RI, and VT can earn $2,250-$3,250 per year, significantly offsetting the cost. Our rating: 9/10.
The aPower 2 is FranklinWH's flagship residential battery. At 15 kWh usable capacity and 10 kW continuous output, it delivers more capacity and more power than any other single residential battery unit. The LFP chemistry provides excellent cycle life and thermal stability, while the IP67 rating means it can be installed anywhere.
| Specification | Value |
|---|---|
| Usable Capacity | 15 kWh |
| Continuous Power | 10 kW |
| Peak Power (10 sec) | 15 kW |
| Round-Trip Efficiency | 89% |
| Chemistry | LFP (Lithium Iron Phosphate) |
| Dimensions | 43.5" x 30.0" x 14.6" |
| Weight | 331 lbs (150 kg) |
| Operating Temperature | -4°F to 131°F (-20°C to 55°C) |
| Ingress Protection | IP67 (fully waterproof) |
| Connectivity | aGate hub + Wi-Fi / Ethernet |
| Scalability | Up to 15 units per aGate (225 kWh) |
| Inverter | External (aGate manages all inputs) |
Most batteries advertise peak power (used for short surges like an AC compressor starting). What matters for sustained use is continuous power. The aPower 2 delivers 10 kW continuous, double the Tesla Powerwall 3's 5 kW. This means you can run a central AC (3.5 kW), EV charger at Level 2 (7.2 kW on a 30A circuit), and your household essentials simultaneously from a single battery. No other single residential battery can make that claim.
The aGate is what separates FranklinWH from every other home battery. It is not just a gateway or a monitoring box. It is a full energy management hub that sits between your main panel and every energy source in your home: solar, battery, grid, and generator.
Every FranklinWH installation requires one aGate ($3,000-$4,000). While this adds to the upfront cost, it provides capabilities that no competitor matches. You buy one aGate per system regardless of how many batteries you add. It supports up to 15 aPower 2 units (225 kWh) from a single controller.
Manages solar, battery, grid, and generator inputs from a single device
Prioritize which circuits get power during outages via the FranklinWH app
Sheds non-critical loads when battery is low to extend backup runtime
Automatically starts a connected generator when battery drops below set threshold
See energy flow from every source and to every circuit in real time
Charge from grid during off-peak and discharge during peak automatically
During multi-day outages (think nor'easters or hurricanes), the aGate automatically starts your generator when battery state of charge drops below your set threshold. The generator charges the battery, the aGate manages distribution, and when the battery is full, the generator shuts off. No manual switching, no transfer switch hassle. This extends backup indefinitely and is a game-changer for homes in outage-prone areas. No other residential battery system offers this level of automated generator integration.
The FranklinWH aPower 2 costs approximately $17,500 fully installed. This is the highest price point among mainstream residential batteries, primarily because the aGate controller is mandatory and adds $3,000-$4,000 to the system cost. Here is the detailed breakdown.
15 kWh LFP battery hardware
Required smart energy hub (one per system)
Wiring, subpanel work, transfer connections
Varies by municipality
Installation typically 5-7 hours
While the total installed price is highest, the cost per kWh tells a different story. The aPower 2 delivers 15 kWh for $17,500, which works out to approximately $1,167/kWh. Compare that to the Tesla Powerwall 3 at approximately $630-$890/kWh (13.5 kWh for $8,500-$12,000) or the sonnenCore+ 10 at $1,500-$1,800/kWh (10 kWh for $15,000-$18,000). The aPower 2 is not the cheapest per kWh, but it is not the most expensive either, especially when you factor in the aGate's capabilities.
Section 25D (the residential clean energy credit) expired December 31, 2025. There is no federal tax credit for standalone battery purchases in 2026. However, batteries installed through a third-party ownership structure (lease or PPA) may still benefit from the commercial Section 48/48E ITC, which the financing company claims. Ask your installer about lease options that may reduce your net cost.
Installing a FranklinWH aPower 2 system is a bigger job than most battery installs because of the aGate controller. Here is what the process looks like from start to finish.
The aGate controller mounts next to your main electrical panel. The installer wires it between the grid connection and your main panel, creating a new energy management layer. All solar, generator, and battery connections route through the aGate.
The aPower 2 mounts to a wall or sits on the floor. At 331 lbs, a two-person crew is required. The IP67 rating means it can go indoors (garage, basement) or outdoors (exterior wall) without any protective enclosure or shelter. Keep it within cable run distance of the aGate.
The installer connects the battery to the aGate, configures circuit-level prioritization in the FranklinWH app, sets backup thresholds, and programs generator auto-start settings if applicable. Solar input is also connected through the aGate at this stage.
Full system test including grid-disconnect simulation, load shedding verification, generator start test (if applicable), and app walkthrough with the homeowner. The installer verifies that all circuits prioritize correctly during simulated outage.
A FranklinWH installation takes longer than a Tesla Powerwall (3-5 hours) because of the aGate controller setup. Plan for a full day with a two-person crew. The aGate integration is more involved but results in a more capable system. Most installers schedule FranklinWH installs as a dedicated full-day job.
The aPower 2 is fully compatible with ConnectedSolutions demand response programs in Massachusetts, Connecticut, Rhode Island, and Vermont. With 10 kW of dispatchable capacity (versus approximately 6 kW for a Tesla Powerwall 3), the aPower 2 earns significantly more annual revenue from demand response events.
Here is the revenue breakdown for a single aPower 2 with approximately 10 kW of dispatchable capacity participating in all eligible demand response events.
| Utility | Summer Rate | Winter Rate | Annual Revenue |
|---|---|---|---|
| Eversource (MA) | $275/kW | $50/kW | ~$3,250/yr |
| National Grid (MA) | $225/kW | $50/kW | ~$2,750/yr |
| RI Energy | $225/kW | -- | ~$2,250/yr |
| Eversource (CT) | $275/kW | $50/kW | ~$3,250/yr |
| GMP (VT) | Varies | -- | ~$1,500/yr |
Revenue estimates based on 10 kW dispatchable capacity participating in all eligible events. Actual revenue varies by dispatch frequency and battery state of charge. ConnectedSolutions dispatches count toward the 60 MWh throughput warranty.
At $2,250-$3,250/year, a single aPower 2 can generate $22,500-$32,500 in ConnectedSolutions revenue over 10 years. Against an installed cost of $17,500, that represents a 129-186% return on investment from demand response alone, before accounting for backup power value and daily bill savings. This is where the aPower 2's higher upfront cost becomes an advantage: more dispatchable kW means more revenue per unit.
15 kWh per unit is the largest single residential battery available, reducing the number of units needed for whole-home backup
10 kW continuous output handles heavy loads like central AC (3.5 kW) + EV charger (7.2 kW) simultaneously on one unit
aGate controller manages solar, battery, grid, and generator inputs with circuit-level load prioritization
IP67 waterproof rating allows outdoor installation without any shelter or enclosure
Seamless generator integration with automatic start/stop during extended outages
Scales up to 15 batteries per aGate for a massive 225 kWh total capacity
15-year warranty with 60 MWh throughput guarantee is among the best in the industry
LFP chemistry provides superior cycle life and thermal stability compared to NMC batteries
$17,500 fully installed is the highest total cost of any residential battery system (includes mandatory aGate)
aGate controller adds $3,000-$4,000 to system cost and is required for every installation
At 331 lbs per unit, it is significantly heavier than competitors (Tesla Powerwall 3 is 287 lbs)
Smaller installer network than Tesla, Enphase, or sonnen, which can mean longer wait times in some regions
89% round-trip efficiency trails Tesla (97.5%) and Enphase (96%), meaning more energy loss per cycle
No federal tax credit for standalone battery installs (Section 25D expired Dec 2025)
FranklinWH offers a 15-year warranty on the aPower 2 with a 60 MWh throughput guarantee. This is one of the most comprehensive residential battery warranties on the market, five years longer than the Tesla Powerwall 3 or sonnenCore+ 10.
The 60 MWh throughput guarantee means the battery is warranted to deliver at least 60,000 kWh of total energy output over 15 years. At one full cycle per day (15 kWh discharge), you would reach 60 MWh in approximately 11 years. Plan your ConnectedSolutions participation and daily cycling accordingly.
| Battery | Term | Guarantee |
|---|---|---|
| FranklinWH aPower 2 | 15 years | 60 MWh throughput |
| Tesla Powerwall 3 | 10 years | 70% capacity |
| Enphase IQ 10C | 15 years | 70% capacity |
| sonnenCore+ 10 | 10 years | 70% capacity |
The aPower 2 competes against the three most popular residential batteries in the Northeast. Here is a head-to-head comparison of every spec that matters for backup performance, efficiency, and long-term value.
| Spec | aPower 2Best for Backup | Powerwall 3 | IQ 10C | sonnenCore+ 10 |
|---|---|---|---|---|
| Usable Capacity | 15 kWh | 13.5 kWh | 10.08 kWh | 10 kWh |
| Continuous Power | 10 kW | 5 kW | 3.84 kW | 4.8 kW |
| Peak Power | 15 kW | 11.5 kW | 7.68 kW | 8.6 kW |
| Round-Trip Efficiency | 89% | 97.5% | 96% | 86% |
| Chemistry | LFP | LFP | LFP | LFP |
| Warranty | 15 yr / 60 MWh | 10 yr / 70% | 15 yr / 70% | 10 yr / 70% |
| IP Rating | IP67 | IP67 | NEMA 3R | NEMA 3R |
| Generator Integration | Yes (auto) | Limited | No | No |
| Price (installed) | $17,500 | $8.5-12K | $10-14K | $15-18K |
| Max Scalability | 225 kWh | 54 kWh | 40+ kWh | 20 kWh |
FranklinWH wins on capacity (15 vs 13.5 kWh), continuous power (10 vs 5 kW), warranty length (15 vs 10 years), and generator integration. Tesla wins on efficiency (97.5% vs 89%), price ($8.5-12K vs $17.5K), and installer availability. Choose FranklinWH for whole-home backup. Choose Tesla for value.
FranklinWH offers 50% more capacity per unit and nearly 3x the continuous power. Enphase excels in modular scalability and ecosystem integration (pairs perfectly with Enphase microinverters). If you have Enphase solar, the IQ 10C is the natural fit. If you want maximum single-unit backup power, FranklinWH wins decisively.
FranklinWH delivers 50% more capacity and double the continuous power at a similar price point. Sonnen has a loyal following for its German engineering and community features, but on raw specs and value per kWh, the aPower 2 is the clear winner. FranklinWH also scales to 225 kWh versus sonnen's 20 kWh maximum.
The aPower 2 carries an IP67 ingress protection rating, meaning it is fully sealed against dust and can withstand submersion in up to 1 meter of water for 30 minutes. In practical terms, this means you can mount it on an exterior wall with zero weather protection. Rain, snow, sleet, coastal salt air — none of it matters.
The wide operating temperature range (-4 to 131 degrees Fahrenheit) covers all New England seasons. For coastal installations in Rhode Island, Massachusetts, or Maine, the sealed design prevents salt air corrosion that can damage NEMA 3R-rated competitors over time.
The aPower 2 is the best battery for certain homeowners and absolutely wrong for others. Here is our honest recommendation after installing dozens of these systems.
NuWatt is a FranklinWH Certified Installer. We provide transparent pricing, handle all permits, configure your aGate for optimal performance, and enroll you in ConnectedSolutions where available. Serving MA, CT, RI, NH, ME, VT, NJ, PA, and TX.