Choosing a home battery system is one of the biggest decisions in a solar installation. The three batteries we move the most volume on at Solwel — the FranklinWH aPower 2, the EG4 WallMount 280Ah, and the Sigenergy SigenStor — each have distinct strengths and tradeoffs. Here's a straightforward breakdown to help you and your customers choose the right one.
Quick Comparison
| FranklinWH aPower 2 | EG4 WallMount 280Ah | Sigenergy SigenStor | |
|---|---|---|---|
| Usable Capacity | 15 kWh | 14.3 kWh | 6 kWh or 9 kWh per pack |
| Power Output | 10 kW continuous | Inverter-dependent | Inverter-dependent |
| Chemistry | LFP | LFP | LFP |
| Max Expandability | 75 kWh (5 units) | Inverter-limited | Inverter-limited, modular stacking |
| Inverter Compatibility | FranklinWH aGate X + select AC-coupled | EG4 inverters + many third-party | Sigenergy SigenStor only |
| Enclosure Rating | Indoor only | IP55 (indoor/outdoor) | Indoor wall-mount |
| Cooling | Passive, 30 dBA | Active | Active |
| Warranty | 12 years | 10 years | 10 years |
FranklinWH aPower 2 — Best For: Premium Residential, Noise-Sensitive Installs
The aPower 2 is FranklinWH's flagship product and arguably the most installer-friendly battery in the residential market right now. It's AC-coupled, which means it connects to the home's AC bus via the aGate X gateway rather than directly to the inverter's DC bus. This simplifies installation significantly — especially on retrofits where a solar system is already in place.
The standout feature is passive cooling. No fans, no moving parts — just 30 dBA of near-silent operation. That makes it viable in living spaces, finished basements, and garages where noise matters. The 12-year warranty is also the longest in its class.
The tradeoff: the aPower 2 requires the FranklinWH aGate X gateway (sold separately) and is a semi-closed ecosystem. It's not a drop-in replacement for a DC-coupled battery on an EG4 or Sol-Ark without careful system design.
Ideal install scenario: Retrofit whole-home backup on an existing grid-tied solar system, premium residential, or projects where the customer prioritizes quiet operation and a long warranty.
EG4 WallMount 280Ah — Best For: EG4 Inverter Systems, Outdoor Installs, Value
The EG4 WallMount 280Ah (14.3 kWh usable) is the natural pairing for EG4's 12kPV and 18kPV hybrid inverters. It communicates via CAN bus and is deeply integrated with EG4's inverter firmware. If you're building an EG4 system from the ground up, the WallMount is the path of least resistance.
Its IP55 rating is a meaningful advantage — it can be mounted outdoors in covered locations or in unconditioned garages and utility rooms without concerns about moisture or temperature exposure. This expands installation flexibility considerably compared to batteries requiring climate-controlled spaces.
The EG4 WallMount also has broad third-party inverter compatibility via standard RS485/CAN protocols — so it's not locked exclusively to EG4 inverters, though native support is deepest there.
Ideal install scenario: New EG4 hybrid inverter systems, outdoor or unconditioned space installs, budget-conscious projects that don't sacrifice quality.
Sigenergy SigenStor Battery Packs — Best For: Sigenergy Ecosystem, Modular Growth
Sigenergy takes a different approach than the other two: the SigenStor battery packs (available in 6 kWh and 9 kWh units) are part of a fully integrated ecosystem where the inverter, battery, EMS, and optional EV charger all come from Sigenergy. The battery packs are not compatible with third-party inverters — they're designed specifically for the SigenStor hybrid inverter.
The modular format is a genuine advantage for projects with phased budgets. An installer can spec a single 6 kWh or 9 kWh pack at initial installation and let the homeowner add packs over time as their storage needs or budget grows. The stacking is clean and the system scales predictably.
For installers already comfortable with the Sigenergy ecosystem — particularly those using the SigenStor inverter for its V2H/EV charging capabilities — the battery packs are the obvious choice. For those unfamiliar with Sigenergy, the closed ecosystem is worth factoring into your decision before committing.
Ideal install scenario: New Sigenergy SigenStor system installations, V2H/EV-integrated projects, customers who want modular capacity growth over time.
Which One Should You Spec?
Here's the short version:
- Retrofit AC-coupled backup on an existing solar system? FranklinWH aPower 2.
- New EG4 hybrid inverter system or need outdoor mounting? EG4 WallMount 280Ah.
- New Sigenergy system or customer wants EV integration? Sigenergy SigenStor packs.
All three use LFP chemistry, all three carry solid warranties, and all three are products we stock and stand behind. If you're working on a project and need help choosing or sizing — call us at (346) 432-4228 or request a quote. Our team works with installers daily and can help you get the right configuration for the job.