Why Sequence Matters
Most homeowners approach electrification as a series of independent decisions: "I'll get solar now, maybe a heat pump later, and eventually an EV charger." Each decision is made in isolation, often years apart, without considering how they interact.
This approach creates three problems:
- Electrical infrastructure bottlenecks — Your switchboard and supply may not handle everything at once
- Missed solar utilisation — Each new electric load should be timed to run on solar, not grid power
- Wasted money on interim solutions — Replacing a gas heater before installing solar means running it on expensive grid electricity
The correct approach treats electrification as a single project with a defined sequence — even if you execute it over 2-5 years.
The Optimal Sequence
Step 1: Solar Panels (The Foundation)
Why first: Everything else runs on electricity. If that electricity comes from the grid at $0.33-$0.45/kWh, your "savings" from electrification are marginal. If it comes from your roof at $0.00/kWh, every subsequent step delivers maximum return.
What to size for: Don't size solar for today's consumption. Size it for your fully-electrified future consumption:
- Current usage: ~20kWh/day (typical 4-person home)
- Add heat pump: +3-4kWh/day
- Add reverse-cycle heating: +5-8kWh/day (winter)
- Add EV charging: +8-12kWh/day
- Future total: 36-44kWh/day
A 10-13kW system (not 6.6kW) is the correct starting point for a home planning full electrification.
Cost: $8,000-$14,000 installed (10-13kW)
Annual value: $2,500-$4,500 in avoided grid imports
Step 2: Heat Pump Hot Water (Highest ROI)
Why second: Hot water is 20-30% of household energy. A heat pump uses 65-80% less electricity than a resistive tank and can be timed to run during peak solar hours (10am-2pm). It's effectively free hot water.
The solar interaction:
- Heat pump draws 1-1.5kWh to heat a full tank
- Timed to midday = runs entirely on solar
- Stores 10-15kWh of thermal energy for evening/morning use
- It's the cheapest "battery" you can buy
Cost: $2,000-$3,500 after rebates
Annual saving vs gas: $800-$1,200
Payback: 2-3 years
Step 3: Reverse-Cycle Heating & Cooling (Replace Gas Ducted)
Why third: Space heating is the second-largest energy consumer in winter. Gas ducted heating costs $3-$6/hour to run. A reverse-cycle system costs $0.50-$1.50/hour — and $0.00/hour when running on solar during the day.
The upgrade path:
- Replace gas ducted with split-system reverse-cycle units (zone-based)
- Or replace with a ducted reverse-cycle system (whole-home)
- Either way: 300-500% more efficient than gas
Cost: $3,000-$8,000 (split systems) or $8,000-$15,000 (ducted)
Annual saving vs gas ducted: $400-$900
Payback: 4-8 years (but comfort improvement is immediate)
Step 4: Battery Storage (Store Your Excess)
Why fourth (not second): A battery's value depends on how much excess solar you have. After adding a heat pump and heating to your solar system, you've increased daytime self-consumption. The battery captures what's left — which is still significant, but less than if you'd installed it before electrifying loads.
Sizing after electrification:
- Your evening consumption is now higher (electric heating, electric cooking)
- But your daytime self-consumption is also higher (heat pump, heating pre-charge)
- Optimal battery size: 10-13.5kWh for most fully-electrified homes
Cost: $8,400-$13,000 installed
Annual value: $1,500-$2,500 (arbitrage + VPP)
Payback: 4-7 years
Step 5: Induction Cooktop (Eliminate Gas Supply)
Why fifth: The cooktop itself uses relatively little energy (1-2kWh/day for a typical family). The real saving is eliminating the gas supply charge — $250-$400/year just to have the gas connection, regardless of usage.
The trigger: Once hot water and heating are electric, the cooktop is often the last gas appliance. Replacing it allows you to disconnect gas entirely — eliminating the supply charge permanently.
Cost: $2,000-$4,000 (cooktop + potentially new circuit)
Annual saving: $250-$400 (supply charge) + $100-$200 (efficiency gain)
Payback: 4-8 years (but accelerates once gas is fully disconnected)
Step 6: EV Charger (Replace Petrol)
Why last: An EV charger draws 7-22kW — more than any other household appliance. Your electrical infrastructure needs to handle this on top of everything else. By this stage, your switchboard has been upgraded (Step 1-2), your solar system is oversized (Step 1), and your battery can buffer charging loads (Step 4).
The economics:
- Average Australian drives 15,000km/year
- Petrol cost: $2,500-$3,500/year (at $1.80-$2.20/L)
- EV charging on solar: $150-$300/year
- EV charging on off-peak grid: $400-$600/year
Cost: $1,500-$3,000 (charger + installation)
Annual saving vs petrol: $1,500-$3,000
Payback: 1-2 years (charger only — the car is a separate decision)
The Full Sequence Summary
| Step | Investment | Annual Saving | Cumulative Annual Saving | Payback |
|---|---|---|---|---|
| 1. Solar (10kW) | $10,000 | $3,500 | $3,500 | 2.9 years |
| 2. Heat pump HW | $2,500 | $1,000 | $4,500 | 2.5 years |
| 3. Reverse-cycle | $6,000 | $650 | $5,150 | 9.2 years |
| 4. Battery (13.5kWh) | $10,500 | $2,000 | $7,150 | 5.3 years |
| 5. Induction cooktop | $3,000 | $350 | $7,500 | 8.6 years |
| 6. EV charger | $2,000 | $2,500 | $10,000 | 0.8 years |
| TOTAL | $34,000 | $10,000 | $10,000/year | 3.4 years (blended) |
The 10-year position: $34,000 invested → $100,000 in cumulative savings → net gain of $66,000 over 10 years. Plus: no gas bills, no petrol bills, and a home that's worth more at resale.
Common Mistakes (And How to Avoid Them)
| Mistake | Why It Happens | What It Costs |
|---|---|---|
| Installing battery before solar | "I want backup power" | Battery charges from grid at $0.33/kWh instead of solar at $0.00 |
| Undersizing solar | "6.6kW is standard" | Not enough generation for future loads — need to add panels later ($3,000+ retrofit) |
| Electrifying before upgrading switchboard | "I'll deal with it later" | Multiple electrician visits, potential safety issues, higher total cost |
| Replacing gas cooktop before gas heating | "I want induction now" | Still paying gas supply charge for heating — no supply charge saving yet |
| Installing EV charger on existing wiring | "It's just a plug" | Overloaded circuits, tripped breakers, potential fire risk |
The C.A.B.L.E. Method™ in Practice
This sequence IS the "L" (Load Electrification) in the C.A.B.L.E. Method — but it only works when informed by the other four decisions:
- C (Current Analysis): Your consumption data determines the right solar size and battery timing
- A (Asset Optimisation): Choosing a hybrid inverter at Step 1 saves $2,000 at Step 4
- B (Battery Strategy): Market timing and VPP availability affect when Step 4 makes sense
- E (Energy Roadmap): Planning all 6 steps from Day 1 avoids costly retrofits
Cable Co's Energy Independence Assessment™ maps this entire sequence for your specific property — including infrastructure requirements, optimal timing, and total investment modelling across 2-5 years.
Cable Co | 1800 117 177 | Vetted Tier 1 Contractor | ABN 64682354605