Why I'm leaving ZeroHero: 5 kW inverter + 15 kWh battery, no exports, and the $1 credit I never once earned
**Edit: correction to the title. It's a 3 kW inverter, not 5 kW.** I misremembered my system; the spec sheet says 3,000 W max output and charge/discharge. That's the real reason I can't get the ZeroHero $1: cooking or running the ACs pushes the house past 3 kW and the grid fills the gap. Details in my comment below. Thanks everyone for making me check!
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Not a hit piece. GloBird has been fine, and ZeroHero is clearly great for some setups. I just worked through the numbers for mine, and it turns out I'm on the wrong kind of plan. Posting in case it helps someone with a similar system.
My setup
- Alpha ESS SMILE, 3 kW inverter, 15 kWh of battery (one 5 kWh unit + 2 extension packs)
- Powercor network, Victoria
- I don't export. The battery is sized to run the house, not to sell power back.
How I actually use power
The free 11 am–2 pm window does almost all the work. Every day the battery charges from the grid in that window, and I run the hot water then too. The battery carries the house through the evening and overnight. In August that was 444 kWh of my 640 kWh (about 16 kWh a day) bought at $0.
Why ZeroHero's extras did nothing for me
- Exports aren't worth it. I don't want to push battery energy into the grid for a few cents and then buy it back later at 33–46c. My whole August export credit was 17 cents.
- I've never earned the $1/day ZeroHero credit, not once, even on days the house was empty. The import allowance in the 6–9 pm window is tiny, and my inverter always seems to pull a small amount from the grid even with a full battery. So on this setup that $1 a day is effectively out of reach.
Take those two features away and what's left is a fairly high supply charge and a high shoulder rate.
The comparison
I log my grid import hourly in Home Assistant and priced every hour under both plans:
- Supply: GloBird $1.518/day → Tango $1.276/day
- Peak: GloBird 46.2c (4–11 pm) → Tango 43.45c (4–9 pm)
- Off-peak / shoulder: GloBird 33.0c → Tango 22.55c (9 pm–11 am)
- 2–4 pm: GloBird 33.0c → Tango 15.95c
- 11 am–2 pm: GloBird free, unlimited → Tango free for the first 24 kWh/day, then 15.95c
Same usage, same hours, 8 Sep–3 Oct:
- GloBird: $73.55
- Tango: $56.62
That's about 22% cheaper, roughly 63c a day, which works out to around $200 a year. That figure only covers the last month, though, which is spring. In winter I use a lot more off-peak power overnight, so I'd expect the real saving to be bigger. Tango came out cheaper on every single day I compared. Nearly all of the difference is the lower supply charge and the much cheaper overnight rate, which is exactly when the battery has run down and I'm topping up from the grid.
The catch to watch
Tango's free window stops being free after 24 kWh a day. My heaviest day so far is about 17 kWh in that window, so I'm fine. If you dump a lot into the battery and run heavy loads at midday, check your own numbers first.
TL;DR: If you export, or can actually hit the ZeroHero evening target, GloBird might well be your best option. If your battery just does free-window charging and you never export, a plain time-of-use plan with a free midday window and a cheaper supply charge can come out well ahead. Worth running your own interval data through both before deciding.
Rates are what's on my bill and offer in the Powercor area and will differ elsewhere. Not affiliated with anyone.