DEBS strategy: how to maximise your solar export earnings in Perth

The Distributed Energy Buyback Scheme (DEBS) pays Perth solar households two different rates for exported electricity: 10c/kWh during the Super Off-Peak window (9am–3pm), and 2c/kWh at all other times. The five-to-one ratio between these rates means the timing of your exports matters significantly. Here's how to work with DEBS rather than against it.

Why DEBS rate structure creates a strategy opportunity

Before DEBS launched in 2020, the Renewable Energy Buyback Scheme (REBS) paid a flat rate regardless of time. DEBS replaced this with time-differentiated export pricing to reflect the grid's actual needs — Western Australia's grid has surplus solar generation midday, making morning and evening exports more valuable.

The result: every kilowatt-hour you export between 9am and 3pm earns you 5× more than an export at other times. On a 10kW system exporting 20kWh/day, the difference between all exports being Super Off-Peak vs all exports being Off-Peak is approximately $21/week.

In practice, most solar generation naturally falls in the 9am–3pm window — panels face peak sun midday. The strategy question is how to shift more of your household consumption OUT of the 9am–3pm window so that generation goes to export rather than self-consumption during that window.

Core DEBS strategy: shift loads away from 9am–3pm

The basic framework:

• Exports at 10c/kWh are worth MORE than avoiding import at 33.26c/kWh when you have a battery to manage timing
• Without a battery, simply running appliances midday still captures self-consumption savings at 33.26c/kWh — which beats the 10c DEBS rate anyway
• With a battery, you can time charging outside the window and discharging during evening peak hours

Load shifting without a battery:

Even without a battery, load timing matters. Running the dishwasher, washing machine, and clothes dryer midday does give you 33.26c/kWh in avoided imports — but it also reduces what you export at 10c/kWh.

The arithmetic: if you run a 2kWh dishwasher cycle at 11am (self-consuming 2kWh of solar), you save 2 × 33.26c = 66.5c. If you instead run it at 7pm (importing 2kWh from the grid) and export that 2kWh at 11am, you earn 2 × 10c = 20c from export but pay 2 × 33.26c = 66.5c for the import — a net loss of 46.5c.

Conclusion without a battery: run loads midday during solar generation. Self-consumption at 33.26c/kWh is still better than exporting at 10c and importing later at 33.26c.

DEBS strategy with a battery

A battery changes the calculation significantly. With a battery, you can:

1. Charge the battery from solar during the Super Off-Peak window (storing value at 10c/kWh export rate foregone)
2. Discharge the battery during evening peak (replacing imports at 33.26c/kWh)
3. Let the battery handle the evening load while any remaining solar exports at 10c/kWh midday

The optimal battery strategy:

For most Perth households with a standard home battery (5–10kWh), the best approach is:

• Set the battery to charge from solar during 9am–3pm (captures cheaper solar)
• Discharge during 3pm–midnight to replace grid imports
• Allow excess solar to export at 10c/kWh during 9am–3pm after the battery is full

This is essentially what most hybrid inverter systems do in their default "self-consumption" or "time-of-use" mode. If your inverter has a manual time-of-use schedule, verify it aligns with the DEBS windows (9am–3pm Super Off-Peak).

Battery charge reserve strategy:

If you're on DEBS and have a battery, starting each day with a low (or near-zero) state of charge allows the battery to absorb more solar during the 9am–3pm window, maximising daytime self-consumption. Arriving at 9am with a full battery means solar spills to export at 10c rather than charging the battery — fine for the economics, but misses the opportunity to charge cheaply.

Set your battery to 10–20% minimum overnight, charge from solar during the day, discharge during the evening.

DEBS and air conditioning timing

Air conditioning is Perth's biggest discretionary load — typically 1.5–5kW draw depending on the unit. The DEBS implication:

Pre-cool before 9am: Run air conditioning from 7am–9am to pre-cool the house. This uses overnight charged battery or grid power (33.26c/kWh import), but it means the house is cool enough during the 9am–3pm window to reduce or eliminate air conditioning. Any solar that would have powered air conditioning midday now exports at 10c/kWh.

The pre-cooling arithmetic: A 3kW AC unit running for 2 hours pre-cooling uses 6kWh at 33.26c/kWh = $2.00. If that 6kWh would otherwise have been used by AC midday (absorbed at 33.26c/kWh self-consumption), the financial difference is zero. But if that 6kWh instead exports at 10c/kWh, you gain $0.60 and spend $2.00 — a net loss.

Revised conclusion: Pre-cooling only beats midday AC if you have a battery or time-of-use awareness. Without a battery, run AC midday when solar is generating rather than running off-peak grid imports.

DEBS and the 2c off-peak window

The 2c/kWh Off-Peak rate (all times except 9am–3pm) is low enough that exporting outside the Super Off-Peak window is essentially worthless. Any generation that spills after 3pm is worth 2c/kWh — far less than the 33.26c/kWh you'd save by self-consuming.

Practical implication: Size your solar system to maximise generation during 9am–3pm and to cover evening loads via a battery. A very large system (13.3kW+) that generates more than your battery can absorb midday will export at 10c/kWh during the window — reasonable at that rate — but any evening excess exports at 2c, which is essentially free generation going to the grid.

Monitoring to verify DEBS strategy

To verify your DEBS strategy is working, compare your Synergy bill's export breakdown:

• The bill should show separate line items for Super Off-Peak exports (10c) and Off-Peak exports (2c)
• If most of your exports are in the Off-Peak category, your panel orientation or load timing is not maximising the Super Off-Peak window

Your inverter monitoring app (Fronius SolarWeb, Sungrow iSolarCloud, Goodwe SEMS, etc.) shows the daily generation curve — verify peak generation is occurring during 9am–3pm.

DEBS is structured to reward solar generation during the middle of the day. Without a battery, the best strategy is to run large loads midday to maximise self-consumption at 33.26c/kWh (which beats exporting at 10c then importing at night). With a battery, charging from solar midday and discharging during the evening peak is the optimal cycle. Pre-cooling or load-shifting away from 9am–3pm only makes sense when a battery handles the associated storage.