Maximising your DEBS feed-in income in Perth

DEBS (Distributed Energy Buyback Scheme) pays two rates for solar electricity exported to the grid:

• 2c/kWh for export during off-peak hours (9pm–3pm)
• 10c/kWh for export during peak hours (3pm–9pm)

The 5× difference between peak and off-peak rates creates an incentive to shift solar export to the peak window. But most residential solar systems export predominantly during the middle of the day — the off-peak window. Here's why, and what you can do about it.

Why most Perth solar export is off-peak

A 6.6kW system in Perth peaks in generation during 10am–2pm — well inside the 9pm–3pm off-peak DEBS window. The 3–9pm peak DEBS window starts just as solar generation is declining (after 3pm, the sun is lower in the sky and panels are generating at 20–40% of their midday peak).

Typical generation by DEBS rate window (clear summer day, 6.6kW north-facing):

• 9am–12pm (off-peak): 15–20kWh
• 12pm–3pm (off-peak): 12–16kWh
• 3pm–6pm (peak): 4–8kWh
• 6pm–9pm (peak): 0–1kWh

Of 30+ kWh generated, approximately 8–9kWh falls in the peak DEBS window — and most of that is likely self-consumed by the household during the late afternoon, leaving only 2–5kWh of surplus export in the peak window.

The real value of DEBS export

Most Perth households receive DEBS export income that is predominantly at the 2c/kWh rate. This is disappointing compared to the headline 10c/kWh peak rate.

Example for a typical Perth household (6.6kW solar, medium consumption):

• Annual export: approximately 5,500kWh
• Peak window export (3–9pm): approximately 500kWh (9% of total)
• Off-peak export: approximately 5,000kWh (91% of total)
• DEBS income: (500 × 10c) + (5,000 × 2c) = $50 + $100 = $150/yr

The headline DEBS rate of "up to 10c/kWh" creates a misleading impression of export income. For most Perth households, effective DEBS income averages 2–3c/kWh on total export.

Self-consumption value comparison: Each kWh self-consumed instead of exported saves 33.26c/kWh (A1) or up to 55.33c/kWh (Midday Saver peak). Self-consumption is always 5–25× more financially valuable than exporting at DEBS rates. This is the primary reason DEBS export income should not be the primary focus of system design decisions.

Can you shift more export to peak?

Strategy 1: battery storage

A battery charges from solar surplus during the off-peak 9am–3pm window, storing energy that would have been exported at 2c/kWh. At 3pm, rather than the battery discharging to power the household (which displaces 55.33c peak import), the battery can be configured to "export at peak" — sending stored energy to the grid at 10c/kWh.

But: is 10c/kWh better than 55.33c/kWh household self-consumption?

10c (DEBS export) < 55.33c (displaced Midday Saver peak import). Exporting at peak always earns less than self-consuming during peak. A battery should always be configured to power the household first, not to maximise DEBS export.

Conclusion: batteries help with self-consumption (valuable), not peak export (low value vs self-consumption).

Strategy 2: west-facing panels

West-facing panels generate more in the late afternoon (2–5pm) when north-facing panels are declining. Some of this falls in the 3–5pm DEBS peak window.

A pure west-facing array on a property with no north-facing roof options generates approximately 17–23% less total energy than north-facing. The additional peak-window generation doesn't compensate for the reduced total generation in most scenarios.

Strategy 3: export limiting and self-consumption focus

Rather than trying to shift export to peak (which has limited benefit), focus on maximising self-consumption during the day:

• Schedule high-draw appliances (hot water, dishwasher, pool pump, EV) to run during 9am–2pm
• Self-consume more midday solar at 33.26c/kWh (A1) rather than exporting at 2c/kWh
• This is a 16× better return per kWh than off-peak export

The REBS alternative

Perth solar households who enrolled by 31 October 2020 on the old Renewable Energy Buyback Scheme receive 7.135c/kWh flat for all export — regardless of time of day.

For most Perth solar export profiles (predominantly midday off-peak generation), REBS at 7.135c/kWh earns more than DEBS (predominantly 2c/kWh).

REBS vs DEBS for typical export profile:

• REBS: 5,500kWh × 7.135c = $392/yr
• DEBS: (500 × 10c) + (5,000 × 2c) = $150/yr

REBS earns approximately 2.6× more than DEBS for this typical profile. Households on REBS should not make system changes that risk triggering loss of REBS status.

Practical recommendations

For new solar buyers (starting on DEBS):

• Don't design your system to maximise DEBS export income — design for maximum self-consumption
• DEBS export income is a secondary benefit; self-consumption savings are the primary return
• Adding a battery is justified by evening self-consumption savings (displacing 55.33c peak import), not by DEBS peak export income

For existing REBS customers:

• Maintain REBS status — confirm any system changes (inverter replacement, adding panels) with Synergy before proceeding
• Your export income is approximately 2.6× higher than a comparable DEBS household
• Adding battery storage is worthwhile for evening self-consumption, but confirm it won't affect REBS eligibility with Synergy first

For households switching to Midday Saver:

• Peak Midday Saver import (55.33c) is 5.5× higher than DEBS peak export (10c)
• Self-consumption during peak hours is always the priority over exporting at peak DEBS rates

Your actual DEBS income appears on your Synergy bill. Upload your bill to BillWise to see your exact peak vs off-peak export split and whether there are consumption scheduling changes that would improve your self-consumption rate.