Alpha ESS vs FoxESS: which battery suits your home?
How this site makes money. We don't earn money from any links on this site yet. If that changes, we'll update this notice first. We don't compare every battery, installer or energy plan in the market. How we make money
Short answer: both are modular batteries that run on their own brand's hybrid inverter. FoxESS comes in smaller steps (4.66 kWh); Alpha ESS comes in 9.3 kWh steps and its official page lists three-phase models up to 20 kW [SB-S054, SB-S074, SB-S204, C]. Neither has a price list with a current seller date we could use, so compare written quotes.
Side by side (as at 3 November 2026)
| Alpha ESS SMILE-G3 | FoxESS EQ4800 | |
|---|---|---|
| Module size (usable) | 9.3 kWh (BAT-9.3S) or 9.6 kWh (BAT-10.1P) [SB-S074, C] | 4.66 kWh [SB-S054, C] |
| Usable range | 9.3–55.8 kWh (9.3 modules); 9.6–57.5 kWh (10.1P) [SB-S074, C] | 9.32–41.93 kWh per stack (2–9 modules) [SB-S054, C] |
| Inverter | Alpha SMILE-G3 all-in-one: S5/B5 single phase; T5/T10 and T15/T20 three phase [SB-S204, C] | Fox hybrid; three-phase H3 Smart 5–15 kW and H3-Pro 15–30 kW [SB-S202, C] |
| Backup | "up to 20 kW backup" on the AU page [SB-S204, C] | H3 Smart EPS output 5–15 kW, switch under 20 ms [SB-S202, C] |
| Warranty | 10 years, 70% or 3.12 MWh per usable kWh, first (BAT-10.1P; 9.3S not named in the Oct 2024 terms) [SB-S210, C] | 10 years, 70% or a throughput cap (L2 39.32 MWh … L9 176.94 MWh), whichever comes first [SB-S055, C] |
| CEC listed until | 31 Dec 2027 (9.3S and 10.1P stacks) [SB-S074, C] | 14 Nov 2027 [SB-S072, C] |
| Dated price | No dated price yet | No dated price yet |
Where they really differ
- Step size. FoxESS adds storage in 4.66 kWh steps, Alpha in 9.3 kWh steps [SB-S054, SB-S074, C]. If you need about 14 kWh, FoxESS gets you 13.98 kWh with 3 modules; Alpha's nearest are 9.3 or 18.6 kWh [SB-S054, SB-S074, E].
- Three-phase homes. Both make three-phase hybrids. Alpha's T15/T20 go to 20 kW; Fox's H3-Pro goes to 30 kW [SB-S204, SB-S202, C]. Alpha's European datasheet (not the AU one) says it can push 150% unbalance per phase [SB-S204, C]; ask whether that applies to the AU model.
- Warranty cap. Alpha's Oct 2024 terms end the warranty at 3.12 MWh per usable kWh, about 3,100 full cycles; FoxESS's 2-module cap (39.32 MWh on 9.32 kWh) is about 4,200 [SB-S210, SB-S055, SB-S054, E]. Alpha's terms don't name the 9.3S module, so ask which document covers yours [SB-S210, C].
- Listing dates. Both stay on the CEC list through most of 2027, so the federal discount isn't at risk on a 2026 install [SB-S072, SB-S074, SB-S003, E].
Who each one suits
Alpha ESS suits you if you want one box with the inverter built in and a three-phase model up to 20 kW [SB-S204, C].
Alpha ESS is not for you if you need a size between its 9.3 kWh steps, or has a 9.3S module, which its Oct 2024 warranty terms don't name [SB-S074, SB-S210, C].
FoxESS suits you if you want to size closely or go big in one stack (to 41.93 kWh) [SB-S054, C].
FoxESS is not for you if you want backup confirmed on a single-phase setup: the EPS figures we hold are for the three-phase H3 Smart [SB-S202, C].
FoxESS three-phase hybrids, warranty caps by size and module steps are in the full FoxESS review [SB-S202, SB-S055, SB-S054, C].
Ask your installer, in writing
- The exact model on the CEC approved list, its usable kWh and listing end date [SB-S026, SB-S003, C].
- How many STCs the quote assumes, and for which install date [SB-S004, C].
- What stays on in a blackout, and the line-item cost of backup.
- Warranty years, the 70% figure and the throughput cap.
Ask at least two accredited installers for a written quote that shows the model, usable kWh and the certificate count.
Rules checked 3 November 2026. Next scheduled check: before 1 January 2027 (STC step-down), and monthly for WA and NSW.