Western Power operates the South West Interconnected System (SWIS) — the electricity network for Perth and southwestern WA. With high solar irradiance (Perth is one of the sunniest capitals in the world) and historically high electricity prices, WA has strong rooftop solar economics. The DEBS buyback scheme replaced the old net metering arrangement, and its time-differentiated rates affect optimal system design.
Western Power’s Network Coverage
Western Power’s network — the SWIS (South West Interconnected System) — covers:
- Perth metropolitan area: All suburbs from Two Rocks in the north to Mandurah in the south, and extending east through the Hills
- South West WA: Bunbury, Busselton, Margaret River, Albany, Esperance
- Wheatbelt and agricultural areas: Northam, Merredin, Katanning, Narrogin
- Midwest coast: Geraldton
Outside the SWIS: The Pilbara, Kimberley, Goldfields, and remote WA areas are not connected to the SWIS. These areas have separate network operators or standalone power systems — typically Horizon Power (the government-owned network for remote WA). Solar connections outside the SWIS have different requirements.
DEBS: The WA Solar Export Arrangement
Western Australia’s DEBS (Distributed Energy Buyback Scheme) replaced the legacy net metering system that previously applied to pre-2018 solar installations.
DEBS rates (2025–26 — check Synergy for current rates):
| Time Period | Day | DEBS Rate (approx.) |
|---|---|---|
| Peak | Mon–Fri, 3pm–9pm | ~10 c/kWh |
| Off-peak | All other times (including weekends, overnight, daytime Mon-Fri outside peak) | ~2.5 c/kWh |
Key implication for system design: Under DEBS, solar generation during the peak solar midday period earns only the off-peak rate (~2.5 c/kWh). The peak rate applies to the afternoon/early evening — when solar generation is declining. This makes battery storage particularly attractive in WA: storing midday surplus (which would earn 2.5 c/kWh as export) and discharging in the evening peak period (displacing import at 30–35 c/kWh retail rate) is financially compelling.
DEBS for new installations: Customers who install solar from 2018 onward are on DEBS. Legacy customers on old state government feed-in tariff arrangements (pre-2011 systems on the now-closed 40 c/kWh or 7.135 c/kWh schemes) have separate arrangements.
Export Limit Policy
Western Power’s standard limits:
- Single-phase: 5 kW maximum export
- Three-phase: 15 kW maximum export
- Systems above 5 kW single-phase: Must configure the inverter with export power limiting
Zero-export areas: Some parts of Western Power’s network — particularly:
- Rural towns in the Wheatbelt with high solar saturation relative to local load
- Some coastal towns (particularly in the South West and Great Southern)
- Agricultural areas where feeder loading is low relative to solar generation
For any regional WA installation outside Perth metro, check the specific address via Western Power’s portal before finalising the design.
The Perth Solar Market: Design Implications
Perth’s combination of high irradiance (Zone 3, rating 1.382 — same as Sydney but with more sunny hours), high electricity prices, 5 kW export limit, and DEBS time-differentiated buyback creates a specific optimal system design profile:
Self-consumption is king: With DEBS off-peak at only ~2.5 c/kWh, exported midday solar is worth far less than avoided import at retail (~32 c/kWh). Maximising self-consumption (sizing to daytime load, using controllable loads during midday) is financially more valuable than maximising export.
Battery storage economics: The combination of high retail rates, low off-peak DEBS export rate, and the 5 kW export limit makes battery storage more financially attractive in Perth than in many other Australian cities. Capturing midday curtailed export for evening use avoids import at peak retail rates.
System sizing: Given the 5 kW export limit and DEBS off-peak rate, oversizing beyond the household’s daytime consumption is less financially compelling than in states with higher feed-in rates. Right-sizing to approximately (daytime consumption) + 5 kW export is the typical optimal approach.
Pro Tip: Model DEBS Rates Correctly in WA Proposals
Many solar proposals in WA incorrectly use a single export rate for all generated energy. Under DEBS, midday solar earns ~2.5 c/kWh while late afternoon export earns ~10 c/kWh. Use solar proposal software that models time-of-generation and the DEBS time-of-use rate to show customers accurate export earnings — proposals that use a single blended rate typically overstate afternoon export value and understate midday export value.
Model DEBS and Export Limits Accurately for WA Solar Projects
SurgePV’s financial model applies DEBS time-differentiated export rates (peak/off-peak) and Western Power’s export limit to produce accurate savings calculations for Perth and SW WA solar installations.
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Frequently Asked Questions
What is Western Power?
The distribution network operator for Perth and SW WA (the SWIS). Manages poles, wires, and solar grid connection approvals.
What is DEBS?
The Distributed Energy Buyback Scheme — WA’s solar export payment programme, managed by Synergy. Pays ~10 c/kWh for peak exports (3pm–9pm Mon-Fri) and ~2.5 c/kWh off-peak. Check Synergy for current rates.
What is the export limit?
5 kW for single-phase, 15 kW for three-phase. Zero export in some constrained regional areas.
Do I need to register for DEBS separately?
The customer registers with Synergy for DEBS after Western Power approves the connection. The DEBS payment appears on the electricity bill as a credit.
Are there zero export areas in WA?
Yes — some rural Wheatbelt towns and regional areas. Check Western Power’s hosting capacity tool for the specific address before designing.
