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NuWatt designs, installs, and manages solar, battery, heat pump, and EV charger systems across 9 states. One company, one warranty, one point of contact.
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NuWatt installs both Tesla Powerwall 3 (13.5 kWh, 11.5 kW continuous, integrated solar inverter, Tesla ecosystem) and Franklin WH aPower 2 (15 kWh, 10 kW continuous, aGate load controller, inverter-agnostic). They're both excellent whole-home backup picks. Pick Powerwall 3 if you want the highest continuous power output, tight Tesla ecosystem integration, or a single-box solar+battery solution. Pick Franklin aPower 2 if you want higher capacity in a single unit, generator integration, inverter-agnostic installation, or a longer warranty (15 years vs 10).
Both are genuine top-tier picks — there's no loser in this comparison. The decision comes down to three factors: (1) do you want integrated solar inverter (Powerwall) or inverter-agnostic (Franklin), (2) how much do you value the Tesla app ecosystem, and (3) do you plan to integrate a generator (Franklin wins).
Power output: Tesla Powerwall 3 wins on peak capability. 11.5 kW continuous / 22 kW peak beats Franklin's 10 kW / 15 kW. If your heaviest loads include a 5-ton central AC, a large well pump, or an EV charger running concurrently with house loads, Powerwall 3 has more headroom.
Capacity: Franklin aPower 2 wins on single-unit capacity. 15 kWh vs Powerwall 3's 13.5 kWh. For longer outage coverage of essential loads, Franklin gives you about 11% more runtime per unit before stacking additional batteries.
Warranty: Franklin aPower 2 has a 15-year warranty vs Powerwall 3's 10 years. Both warranties are backed by financially stable parents (Tesla Inc. vs FranklinWH private). For homeowners who value warranty duration, Franklin wins outright.
Inverter strategy: Powerwall 3 is a unified solar+battery solution. The built-in solar inverter (up to 20 kW DC input) eliminates the need for a separate string inverter in many solar installs, simplifying the wiring and reducing a potential failure point. Franklin aPower 2 uses the aGate controller and is inverter-agnostic — you can install it with any existing or new solar setup, which matters if you already have Enphase microinverters or a SolarEdge system you want to keep.
Ecosystem and app: The Tesla app is one of the most polished in the residential energy space. Real-time monitoring, Storm Watch auto-preparation for incoming storms, Tesla vehicle integration for EV owners, and a unified experience across Powerwall + solar + Tesla cars. Franklin WH has a solid app but the ecosystem is narrower — this matters most for Tesla vehicle owners.
Generator integration: Franklin aPower 2 wins. The aGate controller supports seamless integration with a standby generator for extended multi-day outages. Tesla Powerwall 3 can coexist with a generator on the same home electrical system but the integration is less tight. If you already own a Generac or Kohler standby generator or plan to add one, Franklin is the better pick.
Stacking: Both scale, but Franklin goes further. Powerwall 3 stacks up to 4 units (54 kWh); Franklin aPower 2 stacks up to 15 units per aGate (225 kWh). For unusually large homes or small commercial applications, Franklin has more headroom.
Our practical guidance during a quote: if a homeowner mentions they own a Tesla vehicle, the Tesla ecosystem is usually the deciding factor and Powerwall 3 wins. If they mention they already have a functioning solar system with Enphase microinverters or SolarEdge and don't want to replace it, Franklin aPower 2 wins because it's inverter-agnostic. If they have a well pump or are planning to add an EV charger that runs concurrently with house loads, Powerwall 3's higher peak power output wins. Everyone else is a coin flip — both are top-tier products and neither is a bad choice.
Run the numbers yourself
Pick the appliances you need during an outage and see exact runtime in hours or days. The simulator accounts for duty cycles, peak-surge headroom, and optional solar recharge.
Pick what stays on during an outage
Critical loads
4 selected
Simulated runtime
Battery can handle thisRuntime
2.3
days
Avg load
0.2
kW (of 11.5 kW max)
Peak surge
3.5
kW (of 22 kW peak)
Runtime calculated from 13.5 kWh usable × 97% round-trip efficiency = 13.1 kWh effective storage, divided by average load. Duty cycles assume intermittent operation (fridges cycle ~40% of the time, AC ~50%).
The other NuWatt option
Our highest-capacity single-unit pick. Best for true whole-home backup, high-draw appliances, and homes where generator integration matters.
Capacity
15 kWh
Power
10 kW
Chemistry
LFP
Warranty
15-yr
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Frequently asked
Neither is universally better — they win in different scenarios. Tesla Powerwall 3 has higher continuous and peak power output (11.5 kW / 22 kW vs 10 kW / 15 kW), which matters for homes with large central AC or high-draw loads. Franklin aPower 2 has higher capacity (15 kWh vs 13.5 kWh), a longer warranty (15 years vs 10), and is inverter-agnostic. For Tesla vehicle owners, Powerwall 3 wins on ecosystem integration. For homes with existing Enphase or SolarEdge inverters, Franklin wins because it doesn't require replacing the existing inverter.
Yes, for new installs. Powerwall 3 includes an integrated solar inverter with up to 20 kW of DC input capacity, which means in a new solar install you can eliminate a separate string inverter entirely — the Powerwall handles both battery management and solar inversion in a single box. This simplifies the wiring, reduces one potential failure point, and saves roughly $1,500–$2,500 on the solar install cost. The tradeoff is that if the Powerwall needs servicing, your solar system is also affected.
Both use LFP chemistry, but Franklin WH's warranty terms are genuinely more generous. Franklin backs 15 years with a 60 MWh throughput guarantee; Tesla backs 10 years with 70% capacity retention. The difference reflects different business decisions rather than different product quality — Tesla has a larger installed base and can accept the statistical risk of a shorter warranty, while Franklin WH uses the longer warranty as a market differentiator. For homeowners weighing warranty as a key factor, Franklin wins.
Yes, but the setup is suboptimal. In a home with existing Enphase IQ8 microinverters, adding a Tesla Powerwall 3 means you're running two separate inverter systems — the Enphase AC-side inverters on the solar array and the Powerwall's built-in inverter handling battery functions. This works but doesn't give you the "replace string inverter" savings the Powerwall 3 design optimizes for. For Enphase-equipped homes, the Enphase IQ Battery 10C or the Franklin aPower 2 are both cleaner fits.
Tesla Powerwall 3, on motor-start peak power. Starting a 3-ton central AC from a cold condenser typically requires 15–18 kW of instantaneous inrush current (the "locked rotor amps" or LRA rating). Powerwall 3's 22 kW peak handles this easily. Franklin aPower 2's 15 kW peak is at the edge — it can start most 3-ton AC units but with less headroom. For a 4-ton or 5-ton AC, the Powerwall 3 advantage grows. For homes with the AC on a separate critical load panel that's intentionally shed during outages, this matters less and the Franklin's capacity advantage can dominate.
Physically yes, but we don't recommend it. Mixing two different battery brands adds complexity to warranty service, monitoring (you'd run two different apps), and electrical design. If you want more than ~15 kWh of storage, it's better to stack multiple units of the same brand: Powerwall 3 stacks to 54 kWh (4 units), Franklin aPower 2 stacks to 225 kWh (15 units per aGate). Only exception: some homes have Tesla Powerwall for the daily solar self-consumption + short outage duty and a Franklin aPower 2 + generator setup as extended-outage backup — that's a defensible dual-system architecture but it's unusual.