Tesla Powerwall vs. Enphase IQ Battery vs. FranklinWH: Retrofit Comparison

Powerwall 3 vs. IQ Battery 5P vs. aPower 2: Key specs side by side

If you’re comparing retrofit batteries for an existing solar system, start with capacity: one Powerwall 3 stores 13.5 kWh, each Enphase IQ Battery 5P stores 5.0 kWh, and each Franklin aPower 2 stores 15 kWh. The power output differences matter even more than capacity when you’re sizing for backup needs.

For continuous power, Powerwall 3 delivers up to 11.5 kW, each IQ Battery 5P 3.84 kW, and each aPower 2 10 kW. That difference determines how many appliances you can run simultaneously during an outage—one Powerwall 3 or one Franklin unit can start and run a central air conditioner, while a single Enphase 5P cannot.

All three batteries use lithium iron phosphate (LFP) cells, which generally last longer, tolerate deeper discharge and handle a wider temperature range than older NMC chemistry. Tesla’s Powerwall 3 warranty runs 10 years with a 70% capacity guarantee. Enphase covers the IQ Battery 5P for 15 years or 6,000 cycles, and Franklin covers the aPower 2 for 15 years or 60 MWh of throughput.

The biggest practical difference is modularity. Enphase’s 5P comes in small modules, so an installer can match capacity closely to your needs, while Tesla and Franklin come in fixed 13.5 kWh and 15 kWh increments. If you need 18 kWh of storage, you can use four Enphase 5P units (20 kWh total) for tighter matching, or two Tesla units (27 kWh total) with more headroom but higher upfront cost.

Retrofitting each battery to your existing solar system

The good news: Powerwall 3 can be added to nearly any existing system, regardless of who made your panels or inverter. It’s AC-coupled, so your current solar equipment stays as it is and the Powerwall ties in at your electrical panel. Powerwall 2 was built as an add-on for existing systems and works with all the major inverter brands, and Powerwall 3 continues that compatibility.

Until August 2026, Enphase batteries only worked cleanly with Enphase microinverter systems. That changed when Enphase expanded support so homes with non-Enphase solar can add the IQ Battery 10C and whole-home backup without replacing their existing equipment. The 10C provides 10 kWh of usable storage and 7.08 kW of continuous output, and the IQ Combiner 6C can tie in up to 15.4 kVA of existing third-party solar. The smaller IQ Battery 5P requires an Enphase microinverter system or pairing with the IQ Combiner 6C for third-party solar integration.

FranklinWH supports whole-home backup and can charge from any solar inverter, a generator or the grid. Franklin aPower batteries AC-couple to existing systems the same way Tesla does, making them a strong retrofit choice if you want more capacity per unit than Enphase offers without Tesla’s certified-installer requirement. The aGate controller manages the integration and can connect up to 15 battery units for larger installations.

One critical detail for California homeowners: adding a Powerwall alone doesn’t cost you NEM 1.0 or NEM 2.0 status, because the CPUC treats paired storage as part of your existing system. The same protection applies to Enphase and Franklin retrofits when you’re adding storage without expanding solar capacity. If you’re considering both battery storage and adding more panels, check your state’s net metering rules before designing the project—some states treat system expansions differently than battery-only additions. You can find a local installer who knows your utility’s interconnection requirements.

How much usable capacity and power output do you actually need?

Usable capacity tells you how long the battery runs. Power output tells you how much you can run at once. Most homeowners confuse the two and end up with the wrong battery size.

One Powerwall 3 can keep essentials like the fridge, lights, internet and sump pump running for 24 to 48 hours. Backing up the whole house, including AC, an electric dryer and an EV charger, usually takes two or three. That same logic applies to Franklin and Enphase: one 15 kWh Franklin aPower 2 or three 5 kWh Enphase IQ Battery 5P units give you similar total capacity, but the power output determines what runs simultaneously.

Powerwall 3 can start motors with locked-rotor current up to 185 amps (LRA), and Franklin can surge to 15 kW for 10 seconds, which is enough for a 5-ton AC unit. Enphase IQ Battery 5P peaks at 7.68 kW for 3 seconds, so starting a large central AC typically requires two or three units working together.

If you run high-demand appliances like well pumps, electric heat, or Level 2 EV chargers during outages, prioritize continuous power output over total capacity. A 27 kWh system built from two Tesla Powerwall 3 units (23 kW combined continuous output) will run more simultaneously than a 30 kWh system built from six Enphase 5P units (23 kW combined continuous output), even though the Enphase array has more total storage. Check your main panel to see what breaker sizes your largest loads draw, then size the battery system to match. For help with load calculations and system design, visit our solar savings calculator or connect with an installer who can review your actual usage data.

Installation cost and what’s included

Adding one Powerwall 3 to an existing system typically runs $13,500 to $17,500 installed, and two units roughly $23,000 to $29,000. That price includes the battery, the gateway hardware, electrical work, permits, and utility interconnection filing.

Enphase IQ Battery 5P pricing varies by region and whether you’re adding to an existing Enphase system or integrating with third-party solar. Industry surveys show each IQ Battery 5P usually costs $4,000 to $5,000 before installation. A three-unit system (15 kWh total, roughly comparable to one Powerwall) lands in the $14,000–$18,000 range installed, though exact pricing depends on whether you need the IQ System Controller 3/3G or the newer IQ Combiner 6C for third-party solar integration.

Franklin aPower 2 installed pricing runs similar to Tesla Powerwall on a per-kWh basis, with one 15 kWh unit typically costing $14,000–$18,500 installed depending on your region and installation complexity. The aGate controller adds to the upfront cost but manages energy flow between solar, battery, home, and grid with intelligent automation that adjusts to time-of-use rates.

Important context: batteries bought with cash or a loan in 2026 get no federal tax credit, since Section 25D ended for installations completed after December 31, 2025. State and utility incentives still vary—California’s SGIP, Massachusetts ConnectedSolutions, and similar programs can offset $1,000–$3,000 of installed cost depending on your location and utility. Check current incentives through DSIRE before finalizing your budget. If you’re adding both battery storage and new solar capacity in the same project, different rules may apply—talk to your installer about bundling strategy.

Which battery works best for different existing solar setups

If you already have Enphase microinverters, adding Enphase IQ Battery 5P units gives you the cleanest integration—everything talks through the Enphase App, one warranty contact, unified monitoring. Enphase homes get the simplest path to IQ Batteries, with one app, one monitoring platform and one company to call for warranty. They can also take a Powerwall or any other AC-coupled battery without trouble.

For string inverter systems—SolarEdge, Fronius, SMA, or older systems with brands no longer in business—Tesla Powerwall 3 and Franklin aPower 2 both AC-couple cleanly regardless of your inverter brand. Tesla lists Powerwall as compatible with inverters from SMA, SolarEdge, Fronius, Delta and ABB, as well as Enphase microinverters. Franklin works the same way, charging from any inverter output.

If your installer went out of business or you have an orphaned system (SunPower, Freedom Forever, Titan Solar), both Tesla and Franklin batteries retrofit without requiring the original installer’s involvement. Thousands of California homes left behind by SunPower’s bankruptcy have working panels and dead monitoring. The panels are usually fine, and a Powerwall retrofit, typically paired with a repair and system check, brings monitoring back through the Tesla app. The same logic applies to any system where the installer is gone but the hardware still works. For guidance on orphaned systems and warranty transfers, see our guide on what to do when your installer goes out of business.

One last consideration: if your existing inverter is more than 10-12 years old or showing signs of failure, sometimes the smarter retrofit path is replacing the inverter at the same time you add the battery rather than coupling new storage to aging electronics. A qualified installer will tell you honestly if that’s your situation—if they don’t mention it during the site assessment, ask directly. You can connect with local installers who specialize in battery retrofits and system health assessments.

Monitoring, control, and smart features

All three batteries include smartphone app control, but the feature depth varies. Powerwall includes built-in metering and the Tesla app, learns your usage patterns, and improves through over-the-air updates. You can set backup reserve levels, switch between modes (self-powered, time-based control, backup-only), and monitor solar production, battery charge, home consumption, and grid import/export in real time.

Enphase systems running through the Enphase App offer similarly detailed monitoring plus per-panel production data if you have Enphase microinverters. The intelligence comes from the IQ System Controller, which manages charging and discharging schedules, coordinates with utility time-of-use rates, and handles the grid disconnect during outages. Enphase’s IQ Meter Collar enables whole-home backup without a separate backup subpanel or major rewiring, simplifying installation on retrofit projects.

The aPower 2’s main advantage is FranklinWH’s aGate controller. The aGate learns your usage patterns, forecasts based on local weather, and automatically adjusts charging and discharging to minimize grid usage during peak rate periods. You can override it manually through the Franklin app, but most users report the automation works well enough that they rarely touch it after the first week.

All three systems support utility demand response programs where available—Tesla’s Virtual Power Plant aggregation, Enphase partnerships with programs like ConnectedSolutions in Massachusetts, and Franklin’s grid services mode. These programs pay you to let the utility dispatch stored energy during peak demand events, offsetting part of your battery cost over time. Participation is optional and controlled through the app. For more on how storage economics work with time-of-use rates, see our guide on solar costs in 2026, which covers net metering changes and rate structures.

If your Tesla system shows a fault, see our guide to Tesla inverter error codes.

Real-world differences: What installers report

Installers consistently report that Tesla Powerwall 3 has the tightest supply chain and fastest lead times among the three brands, though availability varies by region. The certified installer requirement means fewer companies can bid the job, which can limit price competition but also ensures the installer has passed Tesla’s training and warranty compliance standards.

Enphase IQ Battery 5P installations go faster when the home already has Enphase equipment—the retrofit is clean and the permitting is straightforward because inspectors recognize the ecosystem. Adding Enphase to a non-Enphase system using the IQ Combiner 6C is newer (launched August 2026), so fewer installers have field experience with that configuration yet. Expect the process to smooth out through late 2026 as more crews get trained.

Franklin aPower 2 systems get strong marks from installers for the aGate controller’s flexibility and the battery’s high power output per unit, which reduces the number of units needed for whole-home backup compared to Enphase. The biggest friction point is installer network size—Franklin has fewer authorized installers than Tesla or Enphase, so availability varies more by geography. If you have a local Franklin-certified installer, the product is competitive; if the nearest one is 90 minutes away, factor in travel time and potential service delays.

Warranty service reputation varies. Tesla handles claims directly and has company-owned service centers in major metros, but rural and small-market owners report slower response times. Enphase warranty claims go through the installing contractor or Enphase directly depending on the issue, and the decentralized installer network means local support quality varies. Franklin warranty support is handled by the installer with manufacturer backup, similar to Enphase. For all three brands, the quality of your installer matters more than the battery brand for fast, hassle-free warranty claims—choose an installer who stocks parts, employs trained service techs, and has a track record of staying in business. Our EnergyScout Verified program highlights installers who meet those standards.