Why Separate Installations Cost You More
The typical Australian homeowner's electrification journey looks like this: install solar in Year 1, add a battery in Year 3, install an EV charger in Year 4. Three separate contractors. Three separate site visits. Three separate switchboard modifications. Three separate design decisions made without knowledge of what comes next.
This approach wastes money in four ways:
1. Duplicate electrical work ($1,500–$3,000 wasted)
Each installation requires switchboard modifications, circuit breaker additions, and cable routing. When done separately, the electrician can't plan ahead — so the battery installer reworks what the solar installer did, and the EV charger installer reworks what the battery installer did.
2. Suboptimal sizing ($2,000–$5,000 in lost savings over 10 years)
A solar system designed without considering future battery and EV loads is typically undersized. A 6.6kW system is fine for a home without an EV. Add a 7kW EV charger and suddenly you need 10–13kW of solar to maintain self-sufficiency.
3. Incompatible equipment ($500–$2,000 to retrofit)
Not all inverters support battery retrofitting. Not all batteries communicate with all EV chargers. When you buy components separately, you risk ending up with equipment that can't share data or optimise as a system.
4. Multiple site visits ($800–$1,500 in access costs)
Each installation requires scaffolding, roof access, switchboard access, and potentially council notification. Combining into one or two visits eliminates repeated setup costs.
"We audited 200 homes that had installed solar, battery, and EV charger separately over 2–4 years. Average wasted cost: $4,200 in duplicate work, suboptimal sizing, and incompatible equipment. The worst case was $11,000 — a home that needed a complete inverter replacement because the original couldn't support battery addition." — Mark Willis, Head of Renewables & Electrification, Cable Co
The Integrated System Design Framework
Step 1: Calculate Your Total Energy Needs (Present + Future)
Don't size for today. Size for the home you'll have in 3–5 years.
| Load | Daily Consumption | Annual Consumption |
|---|---|---|
| Base household (lighting, appliances, cooking) | 8–15kWh | 2,900–5,500kWh |
| Heat pump hot water | 3–5kWh | 1,100–1,800kWh |
| EV charging (average Australian drives 38km/day) | 7–10kWh | 2,500–3,650kWh |
| Pool pump (if applicable) | 4–8kWh | 1,460–2,920kWh |
| Air conditioning (seasonal) | 5–15kWh | 900–2,700kWh |
| Total modern electrified home | 27–53kWh | 9,860–19,345kWh |
Step 2: Size Your Solar System
Rule of thumb: Your solar system should generate 1.3× your total daily consumption to account for weather variability, panel degradation, and seasonal variation.
| Daily Consumption | Recommended Solar | Annual Generation (Sydney) |
|---|---|---|
| 20–25kWh | 8–10kW | 11,700–14,600kWh |
| 25–35kWh | 10–13kW | 14,600–19,000kWh |
| 35–45kWh | 13–16kW | 19,000–23,400kWh |
| 45–55kWh | 16–20kW | 23,400–29,200kWh |
Panel placement for EV owners: If you charge your EV in the evening (most people do), west-facing panels are more valuable than pure north — they generate later in the day when you're about to plug in, and the battery captures the rest for overnight charging.
Step 3: Size Your Battery
Rule of thumb: Battery capacity should equal your evening + overnight consumption minus any off-peak charging you're willing to accept.
| Scenario | Recommended Battery | Why |
|---|---|---|
| Couple, no EV, low usage | 5–7kWh | Small overnight load |
| Family, no EV | 10–13kWh | Covers evening cooking + entertainment + overnight |
| Family + 1 EV | 13.5–15kWh | Covers household + partial EV top-up |
| Family + 2 EVs | 15–20kWh | Covers household + both EVs overnight |
| Family + pool + 2 EVs | 20–30kWh | High overnight load, needs large buffer |
Critical design decision: Should the battery charge the EV, or should the EV charge directly from solar?
- Battery → EV (via AC charger): Simpler, works overnight, but adds a conversion loss (5–8% each way = 10–15% total loss)
- Solar → EV (direct, daytime): More efficient, but requires the car to be home during solar hours
- Hybrid (our recommendation): Solar charges EV directly during the day when home; battery supplements overnight charging when needed
Step 4: Choose Your EV Charger
| Charger Type | Power | Charge Rate | Best For |
|---|---|---|---|
| 7kW single-phase AC | 7kW | ~45km/hour | Most Australian homes |
| 11kW three-phase AC | 11kW | ~70km/hour | Three-phase homes, faster charging |
| 22kW three-phase AC | 22kW | ~130km/hour | High-mileage drivers, three-phase |
| Solar-aware smart charger | 7–22kW | Variable | Maximum solar self-consumption |
Our recommendation for integrated systems: A solar-aware smart charger (Zappi, Sigenergy, or Fronius Wattpilot) that communicates with your inverter and battery. These chargers automatically adjust charging speed based on available solar surplus — charging faster when the sun is strong and slower (or pausing) when generation drops.
Step 5: Select Compatible Equipment
Not all equipment works together. Here are our tested, proven integrated system packages:
Package A: Premium Integration (Best Performance)
- Solar: SolarEdge inverter + optimisers (per-panel monitoring, shade tolerance)
- Battery: Tesla Powerwall 3 (integrated inverter, seamless solar coupling)
- EV Charger: Tesla Wall Connector or Zappi (solar-aware, load management)
- Cost: $32,000–$42,000 installed (after rebates)
- Solar: Fronius Primo/Symo inverter + Trina/Jinko panels
- Battery: BYD Battery-Box Premium HVS (modular, expandable)
- EV Charger: Fronius Wattpilot (native Fronius integration)
- Cost: $24,000–$32,000 installed (after rebates)
- Solar: Enphase microinverters (per-panel, any orientation)
- Battery: Enphase IQ 5P (modular 5kWh units, add as needed)
- EV Charger: EVnex E2 (Australian-made, OCPP, any inverter)
- Cost: $28,000–$38,000 installed (after rebates)
- Solar + Battery + EV: Sigenergy AI Hub (integrated solar/battery/EV in one unit)
- Cost: $26,000–$34,000 installed (after rebates)
- Benefit: Single app, single warranty, AI-optimised energy management
Package B: Best Value (Strongest ROI)
Package C: Maximum Flexibility (Future-Proof)
Package D: All-in-One (Simplest)
Energy Management: Making the System Think as One
The difference between three separate products and an integrated system is the energy management layer. This is the software that decides, every second of every day:
- Should solar charge the battery, the EV, or export to grid?
- Should the battery discharge now or hold for the evening peak?
- Should the EV charger run at full power or throttle back?
- Is a grid outage likely (weather forecast integration)?
Without energy management: Each device operates independently. The battery charges while the EV sits empty. The EV charges from the grid while the battery is full. Solar exports at $0.05/kWh while the EV imports at $0.38/kWh an hour later.
With energy management: The system optimises holistically. Solar fills the EV first (highest value displacement), then the battery, then exports. The battery holds reserve for evening peak. The EV charger throttles during cloud cover and ramps up when generation returns.
Cable Co installs energy management systems from Fronius, SolarEdge, Enphase, and Sigenergy — all configured to optimise for your specific tariff structure and consumption pattern.
Real Installation: The Complete Package in Practice
Client: 4-person family, Balgowlah NSW, 2-storey home, 1 EV (Tesla Model 3), gas hot water (replacing)
System designed:
- 11.7kW solar (26 × LONGi Hi-MO 6, north + west split)
- Fronius Primo GEN24 10.0 inverter (hybrid, battery-ready)
- BYD Battery-Box Premium HVS 12.8kWh
- Fronius Wattpilot 22kW EV charger (three-phase)
- Sanden Eco Plus heat pump hot water (315L)
Costs:
| Component | Gross Cost | Rebates | Net Cost |
|---|---|---|---|
| Solar 11.7kW | $9,800 | -$3,200 (STCs) | $6,600 |
| Battery 12.8kWh | $11,500 | — | $11,500 |
| EV charger 22kW | $3,800 | — | $3,800 |
| Heat pump HW | $5,200 | -$1,800 (STCs + PDRS) | $3,400 |
| Integrated install | — | -$2,500 (vs separate) | -$2,500 |
| Total | $30,300 | -$7,500 | $22,800 |
Performance (first 6 months, monitored):
- Solar generation: 48kWh/day average
- Self-consumption: 82%
- Grid import: 4.2kWh/day (down from 28kWh/day pre-solar)
- Monthly electricity bill: $18 (down from $380)
- Monthly fuel savings (EV vs petrol): $280
- Total monthly savings: $642
- Projected payback: 3.0 years
Why Cable Co for Integrated Systems
Single design, single contractor, single warranty point. We design the complete system as one project — solar, battery, EV charger, heat pump, switchboard, and energy management. No finger-pointing between three contractors when something doesn't work.
50+ integrated installations per week per state. We have the volume to negotiate equipment packages 15–25% below retail, and the experience to install a complete system in 1–2 days instead of 3–4 separate visits over months.
24/7 monitoring from day one. Every component is enrolled in our command centre. We track solar generation, battery cycles, EV charging patterns, and self-consumption rates — adjusting settings remotely to maximise your savings as your usage patterns evolve.
Future-proof design. Every system we install includes spare capacity in the switchboard, conduit for future additions, and inverter selection that supports expansion. When you add a second EV or a pool in 3 years, the infrastructure is already there.