Fox ESS vs BYD Battery-Box: value tier against a household name
BYD's Battery-Box is designed to pair with other brands' hybrid inverters, including Fronius. Fox ESS sells its own batteries and inverters as a set. They answer different questions.
Price, before and after the federal discount
| Brand | Battery | Installed, before rebates | After rebates (VIC) |
|---|---|---|---|
| Fox ESS | 10 kWh | $7,650 to $13,500 | $5,130 to $10,980 |
| Fox ESS | 15 kWh | $12,100 to $18,000 | $8,420 to $14,320 |
| Fox ESS | 27 kWh | $16,470 to $28,000 | $10,980 to $22,510 |
| BYD Battery-Box | 10 kWh | $8,420 to $14,850 | $5,900 to $12,330 |
| BYD Battery-Box | 15 kWh | $13,310 to $19,800 | $9,630 to $16,120 |
| BYD Battery-Box | 27 kWh | $18,120 to $30,800 | $12,630 to $25,310 |
Installed prices from the same calculator the free assessment uses, scaled by tier. The federal battery discount is the same for both[1].
The ranges
BYD has several Battery-Box series on the approved list, including the HVS, HVM, HVE and the newer Battery-Box HVB, from about 5kWh to about 30kWh usable. Fox ESS lists the EQ4800 from 9.32 to 41.93kWh, plus larger CQ6 and CQ7 stacks[2].
The inverter question
BYD's Battery-Box pairs with other brands' hybrid inverters, and on this site's recommender it is the battery that comes up for an existing Fronius system. Fox ESS sells the inverter and battery together. So: already have a compatible inverter you want to keep, BYD is the natural add-on; starting from scratch, Fox ESS gives you both halves at value-tier pricing.
So which
Fox ESS on a new system where price matters. BYD where you are keeping an inverter it pairs with. Either way, check the exact models are compatible, because pairing is model by model.
Get your own numbers, then get them priced properly
Two minutes of questions gets you the battery size your house actually needs, what it should cost after rebates, and what it saves. Then I find the bottom of that price range for you. No installer sees anything unless you ask.
Run my numbers, freeCommon questions
Is BYD better than Fox ESS?
Neither is better in the abstract. BYD is mid tier on this site and pairs with other brands' inverters; Fox ESS is value tier and sells the inverter and battery together.
Can I add a BYD battery to a Fronius inverter?
Often, with a compatible Fronius hybrid model. Check the exact models with your installer.
Which is cheaper?
Fox ESS, by about 10% before rebates on the same capacity on this site's pricing. The federal discount is the same for both.
Sources
- Clean Energy Regulator, Solar batteries (Cheaper Home Batteries Program). Read 2026-10-27.
- Clean Energy Regulator, CEC approved solar batteries (list). Read 2026-10-27.