Case Study: How a Perth Family Cut Their Energy Bills by 85%

Illustrative scenario. The Morrison family is a composite drawn from typical Perth electrification journeys. Names and personal details are fabricated; the costs, savings, and timelines reflect realistic figures for a 4-bedroom Duncraig home using current WA tariff rates and rebate values. This article walks through what the journey looks like — not a profile of any specific household.

When the Morrison family decided to electrify their 1990s-built home in Duncraig, they had one goal: reduce their energy costs without sacrificing comfort. Three years later, their energy bills have dropped from $6,200 to under $900 annually. Here's exactly how they did it.

The Starting Point

The House:

• 4-bedroom, 2-bathroom home built in 1992
• 220m² living area
• North-facing roof (ideal for solar)
• Ducted evaporative cooling, no heating
• Gas hot water, gas cooktop, gas bayonet heater

The Family:

• Parents (Michael, 42, and Sarah, 40)
• Two children (Emma, 14, and Jack, 11)
• Two cars (commuting 25,000km/year combined)

Annual Energy Costs (2022): | Item | Annual Cost | |------|-------------| | Electricity (8,500 kWh) | $2,640 | | Gas (supply + usage) | $760 | | Petrol | $4,200 | | Total | $7,600 |

Year 1: Solar Foundation

The Decision

After receiving a $950 quarterly electricity bill during summer (running the evaporative cooling constantly), Michael started researching solar.

What They Installed

• 10kW solar system (25 x 400W panels)
• 8.2kW Fronius inverter
• North-facing panels at 15-degree tilt
• Total cost: $9,200 after STCs

Why They Chose This Size

"Our roof could fit 10kW, and the installer showed us the payback difference was minimal between 6.6kW and 10kW. Since we were planning to eventually get an EV and battery, we went bigger." - Michael

First Year Results

• Generated: 16,800 kWh
• Self-consumed: 5,200 kWh
• Exported: 11,600 kWh
• DEBS credits: $232 (at 2c/kWh off-peak)
• Electricity bill: $1,100 (down from $2,640)
• First year savings: $1,540
• Payback on track: 6 years

Year 2: Heat Pump Hot Water + Induction

The Catalyst

Their 18-year-old gas hot water system started leaking. Decision time: replace with gas ($1,800 installed) or switch to heat pump?

Heat Pump Installation

• iStore 270L heat pump hot water
• Installed in garage (quiet location)
• Cost: $3,400 installed ($2,600 after STCs)
• Runs during solar production (10am-2pm)

The Induction Switch

While they were at it, Sarah had been researching indoor air quality. With two asthmatic children, she pushed for the induction switch.

• Fisher & Paykel 4-zone induction cooktop: $1,100
• New electrical circuit: $450
• Compatible cookware (kept most existing): $280
• Total: $1,830

Gas Disconnection

With no gas appliances remaining, they disconnected:

• Disconnection fee: $180
• Annual supply charge eliminated: $380

Year 2 Results

| Item | Before | After | |------|--------|-------| | Electricity | $1,100 | $950 | | Gas | $760 | $0 | | Total | $1,860 | $950 |

Year 2 savings: $910 Cumulative savings: $2,450

The Unexpected Benefits

"We didn't expect the cooking experience to be so different. Induction is faster, and the cleanup is so much easier - nothing bakes onto a cool surface. The kids actually help cook more now because it feels safer." - Sarah

"And Jack's asthma has been noticeably better. We can't prove it's the induction, but his puffer use is down about 30%." - Sarah

Year 3: Battery and EV

Battery Decision

With solar exports earning just 2c/kWh off-peak but evening electricity costing 32c/kWh, the Morrisons saw an opportunity.

• Tesla Powerwall 2 (13.5 kWh)
• Installed with Storm Watch feature
• Cost: $13,500 (financed via WA Battery Scheme - interest-free)
• Monthly payment: $112.50 for 10 years

How They Use It

The battery:

1. Charges from solar during the day
2. Powers the home from 5pm-10pm
3. Provides backup during blackouts
4. Participates in Tesla Energy Plan VPP

The EV Leap

Michael's 12-year-old Camry was due for replacement. After researching, they chose:

• BYD Atto 3 Extended Range
• 60.48 kWh battery, 420km range
• Cost: $47,990 (no stamp duty in WA for EVs under $50k)
• Home charging: Dedicated 7kW charger ($1,200 installed)

EV Charging Strategy

"We charge mainly from solar. I plug in when I get home at 4pm, and it grabs the last few hours of solar. The battery still fills enough to run the house overnight. We only use grid power for charging maybe 2-3 times a month." - Michael

Year 3 Results

| Item | Cost | |------|------| | Electricity (minimal grid use) | $380 | | Battery loan payment | $1,350 | | Public charging (occasional) | $150 | | Petrol (second car only) | $1,800 | | Total | $3,680 |

But wait - the second car still uses petrol. Once that's replaced with an EV, their annual energy cost will drop below $1,000.

The Complete Picture

Total Investment Over 3 Years

| Item | Cost | |------|------| | 10kW solar | $9,200 | | Heat pump hot water | $2,600 | | Induction + circuit | $1,830 | | Gas disconnection | $180 | | Battery | $13,500* | | EV charger | $1,200 | | Total | $28,510 |

*Financed interest-free

Annual Savings

| Comparison | Annual Cost | |------------|-------------| | Before electrification (2022) | $7,600 | | After electrification (2025) | $3,680 | | Annual savings | $3,920 |

When the second car is replaced with an EV:

• Projected annual cost: $1,100
• Projected annual savings: $6,500

Payback Analysis

| Investment | Payback Period | |------------|---------------| | Solar | 6 years | | Heat pump + induction | 5 years | | Battery | 23 years (but financing means cash-positive from day 1) | | EV vs new petrol car | 8 years |

Lessons Learned

What Went Right

1. Oversized the solar: "Best decision we made. Extra capacity costs very little but enables everything else."

2. Timed the heat pump well: "Waiting until the gas system failed meant we didn't 'waste' the old unit, and the decision was easier."

3. Interest-free battery finance: "We couldn't have afforded $13,500 upfront. The WA Battery Scheme made it possible with no extra cost."

4. VPP participation: "We get $120/year from Tesla for letting them use our battery during grid stress events. Only lost power for a few hours total."

What They'd Do Differently

1. Bigger battery: "13.5kWh is enough, but 20kWh would let us go completely off-grid on most days."

2. Earlier induction: "We waited until the hot water switch, but should have done induction earlier. The health benefits alone were worth it."

3. Plan for EV from start: "We'd have installed the 7kW charger circuit when doing other electrical work. Would have saved an electrician visit."

Tips for Others

Michael's Advice

"Start with solar. It makes the economics of everything else work. And go bigger than you think you need - electricity use only goes up as you electrify."

Sarah's Advice

"Don't overthink the cooking transition. I was nervous about induction, but within a week it felt natural. My only regret is not doing it sooner for the kids' health."

Financial Advice

"Do the math on financing. We paid $112.50/month for the battery, but it saves us $150-200/month. We're cash-positive from month one. Same with the EV - our petrol savings exceed the car payment."

What's Next?

The Morrisons plan to:

1. Replace their second car with an EV within 2 years
2. Add more battery capacity if prices drop
3. Install smart home automation to optimize energy use
4. Consider a V2H (vehicle-to-home) setup for emergency backup

Want to see what electrification could mean for your household? Try our Electrification Calculator for a personalized analysis based on your specific situation, usage, and location.