The numbers, from each maker’s datasheet
Tesla Powerwall 3: 13.5 kWh of energy per unit, configurable up to 11.5 kW of continuous AC output, and it can start motors rated up to 185 locked-rotor amps. It includes an integrated solar inverter that accepts up to 20 kW of DC solar across six MPPT inputs. Capacity grows with up to three Powerwall 3 Expansion units (13.5 kWh each), and up to four Powerwall 3 units can be combined. Warranty: 10 years. (Source: Tesla Powerwall 3 datasheet, 2025.)
Enphase IQ Battery 10C: 10.0 kWh usable and 7.08 kW continuous output, with starting capability up to 90 locked-rotor amps. It’s AC-coupled, using four built-in microinverters. The limited warranty is 60% capacity for up to 15 years or 6,000 cycles, whichever comes first. Enphase also sells the smaller IQ Battery 5P at 5.0 kWh and 3.84 kW continuous, with a 15-year, 6,000-cycle limited warranty. (Source: Enphase North America datasheets.)
Sigenergy SigenStor: a modular, stackable, DC-coupled system that combines a hybrid inverter, battery modules and, optionally, Sigenergy’s bidirectional EV DC charger in one stack. Sigenergy rates that charger at 25 kW bidirectional. We price SigenStor in roughly 9 kWh modules. Ask us for the current U.S. datasheet for exact usable capacity, continuous power and warranty terms on the configuration we quote; we include it with every proposal.
Our installed prices
Powerwall 3 is about $19,000 installed for the first unit and about $12,000 for each additional. Enphase is about $17,000 for the first 10 kWh. SigenStor is $15,500 for the first ~9 kWh, plus $3,500 for each additional ~9 kWh module, or plus $3,500 to add the bidirectional EV charger. Full bidirectional whole-home backup systems start at $19,000.
Per kWh, the picture depends on size. For a single battery, Powerwall 3 has the lowest cost per kWh, about $1,400. For large banks, Sigenergy’s add-on modules are the cheapest capacity to add. As of September 2026, Colorado’s 10% state income-tax credit on residential batteries still applies for tax year 2026, and batteries are exempt from state sales tax. Verify current terms.
Colorado-specific limits: cold and elevation
All three makers publish temperature and altitude limits, and in Colorado those limits matter. Powerwall 3 is rated from –4°F to 122°F and up to 3,000 m (9,843 ft). Enphase’s IQ Battery 10C is rated to the same –4°F floor and to 3,000 m. It reduces charging power below 59°F and discharge power below 32°F, so we prefer a garage or other sheltered spot.
One Enphase detail matters for mountain homes. Enphase’s datasheet notes that its IQ Meter Collar, used for whole-home backup in some designs, is limited to 2,500 m (about 8,200 ft), and the whole system is limited to its lowest-rated part. Above that elevation, we design around it. We check the elevation limit for every component on high-country jobs, including the Sigenergy stack.
Which house fits Powerwall 3
Powerwall 3 is our usual pick for new solar plus whole-home backup on a typical Front Range house, especially one with central air, a well pump or other heavy motor loads. The 11.5 kW continuous rating and 185 LRA starting capability let one unit carry more of the house than most single batteries, and the built-in solar inverter means one box does two jobs.
It’s a less natural fit when you already have microinverter solar you want to keep as-is, or when you want your EV to back up the house. Powerwall 3 isn’t our bidirectional-charging path.
Which house fits Enphase
Enphase is the natural match for homes with Enphase microinverters, or new systems on shaded or multi-angle roofs where panel-level microinverters make sense. Because it’s AC-coupled, it adds to a microinverter system without redesigning the array. The modular 5 kWh building blocks let you size storage to essential loads rather than buying more than you need.
Plan for the per-unit power. At 7.08 kW continuous per 10C, a home with big simultaneous loads may need two units for whole-home backup, or a partial-home design that backs up the essentials.
Which house fits Sigenergy
SigenStor fits two kinds of customers. The first wants a large battery bank at the lowest added cost per kWh: each extra module is $3,500. The second wants vehicle-to-home backup. Sigenergy’s bidirectional DC charger stacks into SigenStor, so a compatible EV can power the house during an outage. Adding it to a SigenStor system is $3,500.
Vehicle support is the caveat. Sigenergy says V2X functions are limited by each vehicle’s capabilities, and its compatibility list reflects its own field tests, not automaker endorsements. Our bidirectional charging guide covers what to check.
FAQ
Questions we hear
How much energy does a Powerwall 3 store?
13.5 kWh per unit, per Tesla’s datasheet, with up to 11.5 kW of continuous output. Expansion units add 13.5 kWh each.
Is Enphase AC-coupled or DC-coupled?
AC-coupled. The IQ Battery 10C has four built-in microinverters and connects on the AC side, which is why it pairs easily with Enphase microinverter solar.
Which battery is best for backing up a whole house with central air?
Usually Powerwall 3, because of its 11.5 kW continuous output and 185 LRA motor-starting capability, or a multi-unit Enphase or Sigenergy system. We check your largest loads before recommending anything.
Can I mix battery brands?
Generally, no. Each maker’s batteries work with its own controls and switching equipment. Choose one platform and expand within it.
Do these batteries work at high elevation in Colorado?
Powerwall 3 and the Enphase IQ Battery 10C are each rated to 3,000 m (about 9,840 ft), but some supporting components have lower limits. Enphase’s IQ Meter Collar is limited to 2,500 m, for example. We check every component’s rating on mountain installs.
Which battery lets my EV power my house?
Of the three we install, Sigenergy’s SigenStor with its bidirectional DC charger is our vehicle-to-home path. It only works with vehicles that support bidirectional charging with it, so we confirm your vehicle first.