Example Perth savings scenarios
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.
Featured households
- Bills are modelled Synergy bills, one every 2 months.
- 25-year ROI: 25 years of savings, each year growing with Synergy's published price trend and shrinking as panels age, minus what the home paid after rebates.
- Same plan: we assume each home stays on its Synergy plan after the install.
- Supply charge: every bill still has Synergy's daily charge. Solar doesn't remove it.
- No export credit? That's the buyback scheme's size limit for the modelled system. The state sets the schemes and your retailer runs them, and whether you're paid depends on your own system and where you live, so check with Synergy or Energy Policy WA before counting on export income either way.
Modelled scenario: Baldivis family with solar plus battery
Baldivis, WA · Family of 4, 4-bedroom home
Modelled annual electricity cost falls from $3,280 to $838, a saving of $2,442 a year.
42/100 BillWise Score
Bill (every 2 months): $547. Tariff: A1 (Flat Rate).
88/100 BillWise Score
Bill (every 2 months): $140. Annual cost: $838.
Key Issues:
- High evening usage with no solar offset
- Large roof space going completely unused
- Eligible for WA Battery Scheme rebate
- Could benefit from Midday Saver tariff with battery
$2,442
Annual Savings
The solution
- Installer:
- SAA-accredited installer
- Solar System:
- 6.6kW
- Battery:
- 10kWh
- System Cost:
- $17,500
- Rebates:
- -$3,096
- Net Cost:
- $14,404
In this scenario the household pairs a 6.6kW solar system with a 10kWh battery, achieving ~70% self-consumption. The modelled bill falls by roughly three quarters once STC and WA Battery Scheme rebates are applied.Basis: Synergy A1 tariff (33.26c/kWh) + DEBS export at the off-peak rate (2c/kWh) + WA Battery Scheme rebate.
Installation timeline
- Assessment:
- Free online assessment
- Quotes:
- Compare quotes from local installers
- Installation:
- Typical 1-day install
- Activation:
- Grid connection within 1-2 weeks
Modelled scenario: Joondalup retirees with right-sized solar
Joondalup, WA · Retired couple, 3-bedroom home
Modelled annual electricity cost falls from $1,940 to $872, a saving of $1,068 a year.
38/100 BillWise Score
Bill (every 2 months): $323. Tariff: A1 (Flat Rate).
82/100 BillWise Score
Bill (every 2 months): $145. Annual cost: $872.
Key Issues:
- Paying full rate for daytime electricity
- High daytime usage ideal for solar self-consumption
- Fixed income impacted by rising energy costs
- Holds a Pensioner Concession Card, so energy concessions apply
$1,068
Annual Savings
The solution
- Installer:
- SAA-accredited installer
- Solar System:
- 5kW
- System Cost:
- $5,200
- Rebates:
- -$1,357
- Net Cost:
- $3,843
In this scenario a daytime-home retired couple installs a 5kW solar system sized to their consumption, achieving ~38% self-consumption. The system is paid off in about 4 years against the modelled saving.Basis: Synergy A1 tariff (33.26c/kWh) + DEBS export at the off-peak rate (2c/kWh) + STC rebate.
Installation timeline
- Assessment:
- Free online assessment
- Quotes:
- Compare quotes from local installers
- Installation:
- Typical half-day install
- Activation:
- Grid connection within 1-2 weeks
Modelled scenario: Canning Vale EV household with solar plus battery
Canning Vale, WA · Professional couple with EV, 4-bedroom home
Modelled annual electricity cost falls from $3,920 to $824, a saving of $3,096 a year.
35/100 BillWise Score
Bill (every 2 months): $653. Tariff: A1 (Flat Rate).
91/100 BillWise Score
Bill (every 2 months): $137. Annual cost: $824.
Key Issues:
- Charging EV at the flat rate (33.26c/kWh) instead of the EV Add-On overnight rate (19.92c/kWh)
- Not utilising Midday Saver or EV Add-On tariffs
- High daytime generation potential going to waste
- Spending $3,500+/year on petrol for second car
$3,096
Annual Savings
The solution
- Installer:
- SAA-accredited installer
- Solar System:
- 8kW
- Battery:
- 10kWh
- System Cost:
- $20,500
- Rebates:
- -$3,495
- Net Cost:
- $17,005
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. At 8kW the system sits above the DEBS eligibility cap, so it is paid nothing for what it exports and every dollar of the saving comes from electricity it no longer buys. The saving shown counts electricity only, not the fuel it stops buying.Basis: Synergy A1 tariff (33.26c/kWh), the rate the avoided grid import is priced at + no DEBS export payment (above the 6.6kW DEBS eligibility cap) + WA Battery Scheme rebate. Moving overnight EV charging to the Synergy EV Add-On rate (19.92c/kWh) is a further saving this scenario does not count.
Installation timeline
- Assessment:
- Free online assessment
- Quotes:
- Compare quotes from local installers
- Installation:
- Typical 1-2 day install
- Activation:
- Grid connection within 1-2 weeks
Modelled scenario: Rockingham family with 6.6kW solar only
Rockingham, WA · Young family with 2 kids, 3-bedroom home
Modelled annual electricity cost falls from $2,720 to $1,395, a saving of $1,325 a year.
44/100 BillWise Score
Bill (every 2 months): $453. Tariff: A1 (Flat Rate).
84/100 BillWise Score
Bill (every 2 months): $233. Annual cost: $1,395.
Key Issues:
- High summer cooling costs with reverse-cycle AC
- Working from home 2 days/week increases daytime usage
- Good north-facing roof but no solar installed
- Budget-conscious, prioritising lowest cost option
$1,325
Annual Savings
The solution
- Installer:
- SAA-accredited installer
- Solar System:
- 6.6kW
- System Cost:
- $6,200
- Rebates:
- -$1,796
- Net Cost:
- $4,404
In this scenario a budget-conscious family installs 6.6kW of solar (no battery) with partial daytime occupancy, achieving ~35% self-consumption. Roughly two thirds of the generation is exported, and export earns far less than the retail rate it would have offset.Basis: Synergy A1 tariff (33.26c/kWh) + DEBS export at the off-peak rate (2c/kWh) + STC rebate.
Installation timeline
- Assessment:
- Free online assessment
- Quotes:
- Compare quotes from local installers
- Installation:
- Typical 1-day install
- Activation:
- Grid connection within 1-2 weeks
Modelled scenario: Mandurah pool household with 10kW solar plus Midday Saver
Mandurah, WA · Family with pool, 4-bedroom home
Modelled annual electricity cost falls from $3,800 to $1,857, a saving of $1,943 a year.
36/100 BillWise Score
Bill (every 2 months): $633. Tariff: A1 (Flat Rate).
86/100 BillWise Score
Bill (every 2 months): $310. Annual cost: $1,857.
Key Issues:
- Pool pump running 6-8hrs/day on flat rate
- High summer cooling costs on top of pool
- Could shift pool pump to cheap midday hours
- Large north-facing roof ideal for bigger system
$1,943
Annual Savings
The solution
- Installer:
- SAA-accredited installer
- Solar System:
- 10kW
- System Cost:
- $8,800
- Rebates:
- -$2,753
- Net Cost:
- $6,047
In this scenario a pool-owning household installs 10kW of solar and shifts the pool pump to the midday solar window, achieving ~38% self-consumption. At 10kW the system is above the DEBS eligibility cap, so it earns nothing for export and is worth installing only because the pump and the pool soak up the generation on site. Shifting the pump is what does the work: the same system with the pump running overnight would save materially less.Basis: Synergy A1 tariff (33.26c/kWh), the rate the avoided grid import is priced at + no DEBS export payment (above the 6.6kW DEBS eligibility cap) + STC rebate. Moving the pump to a Midday Saver plan is a further saving this scenario does not count.
Installation timeline
- Assessment:
- Free online assessment
- Quotes:
- Compare quotes from local installers
- Installation:
- Typical 1-day install
- Activation:
- Grid connection within 1-2 weeks
Ready to see your own numbers?
Analyse your bill for a personalised BillWise Score, then model your own solar and battery savings.