Diamond Energy is a smaller retailer with a long history in renewables, and its WATTBANK VPP is aimed squarely at Sungrow and AlphaESS owners. Instead of paying per event, it pays a fixed annual credit that depends on your system size, then adds a Battery Usage Credit of 30c per kWh for energy you export between 6pm and 8am.
That second part is the interesting bit. 30c per kWh for evening and overnight exports is well above most standard feed-in rates, and it rewards the battery for doing something useful for the grid at the time of day that matters most.
Who it suits
- Sungrow and AlphaESS owners, which are the brands Diamond supports.
- Bigger systems: the annual credit steps up from $250 to $450 as your battery and inverter grow.
- People happy to be on a retailer's standard market offer rather than chasing promotional plans.
Who should skip it
- Owners of any brand other than Sungrow or AlphaESS.
- Small systems under 5kWh of usable battery or 5kW of solar, which are not eligible.
- Anyone who wants a published backup reserve. Diamond can discharge part or all of the battery.
Diamond WATTBANK at a glance
| Provider | Diamond Energy |
| Plan | Diamond Energy WATTBANK VPP |
| Status | Open when checked. Residential customers only. |
| States | SA, VIC, NSW, QLD |
| Networks / regions | SA, VIC, NSW and QLD (Energex network only). |
| How it pays | Credits plus event payments: A fixed annual credit by system block ($250 to $450 inc GST), plus a 30c per kWh Battery Usage Credit for exports between 6pm and 8am. |
| Sign-up bonus | None. There is a $68 establishment fee (waived if you finance through Plenti). |
| Control and reserve | Diamond can charge or discharge part or all of the battery, including from the grid, and may fit a controller. No reserve level is published. |
| Contract and exit fees | No lock-in contract and no exit fees. $68 establishment fee to join. |
| Switch retailer? | Yes. You must be a Diamond Energy customer on its standard market offer (it can't be combined with promotional plans). |
| State incentive link | Diamond is on IPART's list of NSW VPP certificate providers. We could not verify an SA VPP incentive arrangement. |
| Last checked | Sep 2026, against the provider's own pages |
How the money actually works
There are two parts. The first is an annual credit set by which block your system falls into, including GST: Block 1 is $250 (5 to 10kWh), Block 2 is $275 (up to 10kWh with up to an 8kW inverter), Block 3 is $350 (up to 16kWh) and Block 4 is $450 (up to 20kWh). If Diamond can't verify your system, you get Block 1.
The second is the Battery Usage Credit: 30c for every kWh you export between 6pm and 8am. Your battery earns this whenever it pushes stored solar back to the grid in the evening or overnight, not only during events.
Against that, there is a one-off $68 establishment fee to join, waived if you finance your system through Plenti.
Worked example: a 13.5kWh battery for a year
Built only from Diamond Energy's published terms, with every assumption spelled out.
- Published: Block 3 annual credit of $350 (up to 16kWh); 30c per kWh exported 6pm to 8am; $68 establishment fee.
- Assumption: Diamond verifies a 13.5kWh system into Block 3. Confirm your block with Diamond.
- Assumption: the battery exports 2kWh a night between 6pm and 8am, on average, after covering the house. That is our figure for illustration.
The overnight export is the big unknown. Many homes use most of their battery themselves in the evening, which is usually worth more than 30c per kWh anyway. These are VPP credits only, separate from the federal battery discount and any state incentive. Check whether Diamond caps the Battery Usage Credit before you rely on it.
Which batteries work with Diamond WATTBANK
This is Diamond Energy's own compatibility list as published when we checked. Lists change, and it is often the exact model, inverter and firmware that matter, not just the brand, so confirm your system with Diamond Energy before you count on the numbers.
- Most Sungrow batteries
- Most AlphaESS batteries
- Minimum 5kWh usable battery, 5kW (DC) of solar and a 3kW inverter
Read up on the brands we cover: Sungrow, AlphaESS.
The catch: fine print worth reading first
- Only Sungrow and AlphaESS. Diamond says "most" models of each are supported. Check yours.
- Diamond can use the whole battery. The terms allow it to charge or discharge part or all of the battery, including from the grid, and no reserve is published.
- Standard offer only. You must be on Diamond's standard market offer, not a promotional plan, so compare those usage rates with what you pay now.
- A controller may be installed. It needs an Ethernet port near the battery or router.
- Old terms document. The WATTBANK terms we found were issued in February 2023. Ask for the current version.
Other things to know
- If Diamond cannot verify your system details, you are put in Block 1 ($250) by default, so have your installer paperwork handy.
- Diamond may install a controller at your home to talk to the battery. It needs a spare Ethernet port.
- The WATTBANK terms document we read was issued in February 2023. Ask Diamond whether a newer version applies.
How it sits next to your battery rebates
Diamond Energy appears on IPART's list of NSW VPP certificate providers, which is how the NSW VPP incentive is delivered. Diamond does not publish the amount it passes on, so ask before you sign. Whatever it is, the NSW incentive is a separate amount from Diamond's annual and usage credits, and separate again from the federal discount on the battery.
We always treat these as separate numbers: the federal Cheaper Home Batteries discount comes off the battery invoice, any state incentive is its own amount with its own rules, and VPP payments are ongoing credits on your power bill. Check your state: SA battery rebates, VIC battery rebates, NSW battery rebates, QLD battery rebates. Then run your own numbers in the savings calculator before you add any VPP income on top.
Alternatives worth comparing
- Powershop Virtual Power Plant (Powershop): a flat monthly credit by battery size, with Sungrow and AlphaESS on its list.
- GloBird ZEROHERO with VPP (GloBird Energy): daily evening credits plus $1 per kWh critical peak events, also open to Sungrow and AlphaESS.
- AGL Virtual Power Plant (AGL): per-kWh event credits for AlphaESS SMILE and Sungrow SBR or SBH owners.
Or see every plan side by side in our VPP plan comparison, and read how to compare VPP providers if you are weighing a few up.
Where these facts come from
We checked Diamond Energy WATTBANK VPP against Diamond Energy's own published pages and documents in Sep 2026. VPP offers get repriced often, so treat this as a starting point and read the current offer before you sign.