Why Price Comparison Fails for Solar
The solar industry has trained Australian homeowners to compare quotes like they're buying a commodity. Get three quotes. Pick the cheapest. Done.
This approach works for commodities — products where the specifications are identical and only the price varies. Solar is not a commodity. Two systems with identical panel counts and identical prices can deliver wildly different outcomes over 20 years, depending on five decisions that most buyers never evaluate.
Decision 1: Current Energy Analysis (The "C" in C.A.B.L.E.)
Before you size a solar system, you need to understand your actual energy consumption pattern — not just the total, but when you use it.
What most installers do: Look at your quarterly bill, see "20kWh/day average," and recommend a 6.6kW system.
What actually matters:
- When do you consume the most energy? (Morning, midday, evening?)
- What's your base load? (The minimum your house draws 24/7)
- What are your peak loads? (Pool pump, air con, oven, EV charger)
- How much can you shift to solar hours? (Timers, behaviour changes)
| Consumption Pattern | Optimal System Design | Why |
|---|---|---|
| High daytime use (home office, pool) | Standard solar, smaller battery | Self-consumption is already high |
| High evening use (family home, cooking) | Larger solar + battery | Need to store daytime generation |
| High base load (server, aquarium, medical) | Oversized solar + battery | 24/7 demand needs storage |
| Seasonal variation (heating/cooling) | Sized for shoulder season + battery | Avoid oversizing for 2 months of peak |
The cost of skipping this step: A system sized on average consumption without understanding the pattern typically underperforms by 15-25% on self-consumption — meaning you export more cheap energy and import more expensive energy than necessary.
Decision 2: Asset Optimisation (The "A" in C.A.B.L.E.)
The inverter is the brain of your solar system. It determines:
- How efficiently DC panel power converts to AC household power
- Whether you can add a battery later without replacing equipment
- How long your system operates before its first failure
- Whether you get panel-level monitoring or system-level only
The inverter decision matrix:
| Factor | Premium (Fronius, SMA, Enphase) | Mid-Range (GoodWe, Sungrow) | Budget |
|---|---|---|---|
| Efficiency | 97-98.5% | 96-97.5% | 94-96% |
| Warranty | 10-15 years | 10 years | 5-10 years |
| Expected lifespan | 15-20 years | 12-15 years | 8-12 years |
| Battery compatibility | Extensive | Limited | Minimal |
| Monitoring | Panel-level | System-level | Basic |
| Failure rate (in warranty) | <2% | 3-5% | 8-15% |
The maths: A premium inverter costs $500-$1,500 more upfront. A mid-range inverter failure at year 8 costs $2,000-$3,500 to replace (parts + labour + lost generation). The premium inverter pays for itself by avoiding one replacement.
Decision 3: Battery Strategy (The "B" in C.A.B.L.E.)
The battery decision isn't "should I get one?" — it's "when is the right time, and what size?"
Buy a battery NOW if:
- Your feed-in tariff is below $0.05/kWh AND your import rate exceeds $0.35/kWh
- You have time-of-use pricing with peak rates above $0.45/kWh
- You experience regular blackouts (value = avoided disruption)
- You're installing solar for the first time (combined installation saves $1,000-$2,000 in labour)
- Your feed-in tariff is still above $0.08/kWh
- You're on a flat tariff below $0.30/kWh
- Battery prices are dropping 10-15% annually in your size range
- Your consumption pattern hasn't stabilised (new home, lifestyle changes)
Wait 12-24 months if:
The sizing formula:
`
Optimal battery size = (Evening consumption from sunset to sunrise) - (Base load × overnight hours × 0.3)
`
For most Australian households: 10-13.5kWh covers 80-90% of overnight needs without oversizing.
Decision 4: Load Electrification Sequence (The "L" in C.A.B.L.E.)
If you're planning to replace gas appliances with electric alternatives, the ORDER matters:
| Priority | Appliance | Why This Order | Typical Savings |
|---|---|---|---|
| 1st | Hot water (heat pump) | Highest energy use, runs on solar, biggest bill impact | $800-$1,200/year |
| 2nd | Space heating (reverse cycle) | Second highest energy use, replaces gas ducted | $400-$900/year |
| 3rd | Cooktop (induction) | Lower energy but eliminates gas supply charge | $250-$400/year (supply charge) |
| 4th | EV charger | Replaces petrol cost entirely | $1,500-$3,000/year |
Why sequence matters: Each electrification step increases your electricity consumption. If you electrify everything simultaneously without adjusting your solar/battery system, you'll overshoot your generation capacity and end up importing expensive grid power for loads that should run on solar.
The correct approach: electrify one load at a time, adjust timers and solar utilisation, then add the next.
Decision 5: Energy Independence Roadmap (The "E" in C.A.B.L.E.)
The system you install today needs to work with everything you'll add over the next 10 years. This means:
- Switchboard capacity: Do you have enough circuits for a battery, EV charger, heat pump, and induction cooktop? If not, the switchboard upgrade should happen with solar installation (saves a second electrician visit).
- Inverter headroom: A hybrid inverter installed now can accept a battery later without replacement. A standard inverter cannot.
- Wiring gauge: Cables sized for current loads may not handle future additions. Upgrading later means pulling new cables through walls.
- Meter configuration: Single-phase limits you to 5kW export. Three-phase allows 15kW. If you're planning significant electrification, the phase upgrade should happen early.
The cost of not planning ahead:
| Retrofit Item | Cost If Done With Solar | Cost If Done Later | Wasted Spend |
|---|---|---|---|
| Switchboard upgrade | $800-$1,200 | $1,500-$2,500 | $700-$1,300 |
| Three-phase upgrade | $2,500-$4,000 | $3,500-$5,500 | $1,000-$1,500 |
| Battery-ready wiring | $200-$400 | $800-$1,500 | $600-$1,100 |
| CT clamp installation | $150-$250 | $350-$500 | $200-$250 |
The C.A.B.L.E. Method™ Summary
| Letter | Decision | Question It Answers |
|---|---|---|
| C | Current Energy Analysis | What do I actually use and when? |
| A | Asset Optimisation | What equipment gives me the best 20-year outcome? |
| B | Battery Strategy | When should I buy, and what size? |
| L | Load Electrification | What order should I replace gas appliances? |
| E | Energy Roadmap | How do I plan for the next 10 years? |
What This Means for Your Next Quote
When you receive a solar quote, evaluate it against all five C.A.B.L.E. decisions — not just the bottom-line price. A quote that addresses all five will typically cost 10-20% more upfront but deliver 30-50% better outcomes over 20 years.
Cable Co's Energy Independence Assessment™ evaluates all five decisions before recommending a system. We analyse your interval data, assess your property's electrical infrastructure, model your future electrification pathway, and design a system that performs for two decades — not just one that looks good on paper today.
Cable Co | 1800 117 177 | Vetted Tier 1 Contractor | ABN 64682354605