Each scenario below is an illustrative model of a Perth Synergy household moving through bill analysis, system sizing, installation, and a first year on solar and battery. The figures are modelled on real WA tariffs, rebates and 2025–2026 system pricing. They are not measured customer bills. Run the calculator to estimate your own.
Bill amounts shown are the Synergy billing-period totals. ROI uses conservative tariff escalation (2% p.a.) and assumes the household stays on the same plan post-installation.
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Modelling note
In this scenario the household pairs a 6.6kW solar system with a 10kWh battery, achieving ~70% self-consumption. The modelled quarterly bill drops from $820 to ~$222 and annual savings reach ~$2,390 after STC and WA Battery Scheme rebates are applied.
Basis: Synergy A1 tariff (32.37c/kWh) + DEBS weighted export (~5c/kWh) + WA Battery Scheme rebate of $1,300.
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Modelling note
In this scenario a daytime-home retired couple installs a 5kW solar system sized to their consumption, achieving ~40% self-consumption. The modelled annual saving is ~$1,200 with a $3,843 net out-of-pocket after STC rebate.
Basis: Synergy A1 tariff (32.37c/kWh) + DEBS weighted export (~5c/kWh) + STC rebate.
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Modelling note
In this scenario an EV-owning household pairs an 8kW solar system with a 10kWh battery and shifts EV charging to the daytime solar window, achieving ~75% self-consumption. Modelled annual electricity saving is ~$3,060 plus ~$1,800/yr in fuel offset versus petrol.
Basis: Synergy EV Add-On tariff (19.38c/kWh overnight) + A1 daytime + DEBS weighted export + WA Battery Scheme rebate.
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Modelling note
In this scenario a budget-conscious family installs 6.6kW of solar (no battery) with partial daytime occupancy, achieving ~35% self-consumption. Modelled annual saving is ~$1,960 with a $4,404 net out-of-pocket after STC rebate.
Basis: Synergy A1 tariff (32.37c/kWh) + DEBS weighted export (~5c/kWh) + STC rebate.
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Modelling note
In this scenario a pool-owning household installs 10kW of solar and shifts the pool pump to the midday solar window, achieving ~45% self-consumption. Modelled annual saving is ~$2,900 with a $6,047 net out-of-pocket after STC rebate.
Basis: Synergy A1 tariff (32.37c/kWh) shifted to Midday Saver effective rates + DEBS weighted export (~5c/kWh) + STC rebate.