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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.
Get a Free QuoteWhich is better for your home? We install both. Here's our honest, spec-by-spec comparison based on real installation experience.
The FranklinWH aPower 2 wins this head-to-head comparison, taking 4 out of 5 categories. It's the stronger choice for most homeowners, especially those who prioritize true whole-home backup with highest capacity (15 kwh). That said, the sonnen sonnenCore+ 10 is still a solid product and may be the better pick if you specifically need time-of-use rate optimization (buy low, sell high).
FranklinWH · aPower 2
sonnen · sonnenCore+ 10
| Spec | FranklinWH | sonnen |
|---|---|---|
| Usable Capacity | 15 kWh | 10 kWh |
| Continuous Power | 10 kW | 4.8 kW |
| Peak Power | 15 kW (10 sec) | 8.5 kW |
| Round-trip Efficiency | 89% | 91% |
| Chemistry | LFP (Lithium Iron Phosphate) | LFP (Lithium Iron Phosphate) |
| Weight | 331 lbs (150 kg) | 198 lbs (90 kg) |
| Dimensions | 43.5 x 30.0 x 14.6 in | 56.0 x 24.0 x 10.0 in |
| Operating Temp | -20°C to 55°C | -5°C to 45°C |
| Connectivity | FranklinWH aGate + Wi-Fi/Ethernet | Wi-Fi / Ethernet |
We evaluate each product across the metrics that matter most to homeowners.
FranklinWH aPower 2 offers a longer 15-year warranty vs 10 years.
sonnen sonnenCore+ 10 is more affordable at $16,000 installed vs $17,500 installed (with aGate).
Our crew rates the FranklinWH aPower 2 higher at 9/10 vs 7.5/10.
FranklinWH aPower 2 offers more storage at 15 kWh vs 10 kWh.
FranklinWH aPower 2 delivers more power at 10 kW vs 4.8 kW.
The aPower 2 is our whole-home backup champion. The aGate controller installs next to the main panel and handles automatic load management — it can prioritize circuits and integrate with a generator for extended outages. Total install runs 5-7 hours with a two-person crew. IP67 rating means we can mount it outdoors without a shelter. Best choice when the customer wants to back up everything including central AC and EV charger.
The sonnenCore+ is an all-in-one system — battery, inverter, and energy management in one box. Installs in 3-4 hours with a single crew. It's the lightest battery in our lineup at 198 lbs, making wall mounting straightforward. The TOU optimization mode is excellent for customers on time-of-use rates who want to minimize grid purchases during peak hours. We install these less frequently than Tesla or Enphase, but they're a solid choice for TOU-focused customers.
The FranklinWH aPower 2 wins this head-to-head comparison, taking 4 out of 5 categories. It's the stronger choice for most homeowners, especially those who prioritize true whole-home backup with highest capacity (15 kwh). That said, the sonnen sonnenCore+ 10 is still a solid product and may be the better pick if you specifically need time-of-use rate optimization (buy low, sell high).
Our energy advisors can help you decide between the FranklinWH aPower 2 and sonnen sonnenCore+ 10 based on your specific home, budget, and energy goals.
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