How to read a solar quote in Perth: what the specifications actually mean

Getting three solar quotes is standard advice. Less common: knowing how to read what you've been sent. Solar quotes range from one-page summaries to multi-page documents with performance projections, and the specification details matter more than the headline price.

Here's what each section of a Perth solar quote should contain and what to look for.

System size

What it says: Usually expressed in kilowatts (kW) — for example, "6.6kW system."

What it means: The total combined rated output capacity of all panels. This is not the inverter size. A 6.6kW system with a 5kW inverter is standard — the panel oversize ratio accounts for the fact that panels never all produce their rated peak simultaneously.

What to check: Make sure you're comparing like with like across quotes. A "5kW system" from one installer and a "6.6kW system" from another aren't the same — the second will produce roughly 30% more electricity annually.

The annual generation estimate (often listed in kWh/year) lets you compare different-sized systems. For Perth, a rule of thumb is 1,400–1,600 kWh/year per installed kWp (kilowatt-peak of panels). A 6.6kWp system should produce 9,000–10,600 kWh/year.

Panels

What to look for:

• Brand and model number — not just brand name. "LONGi" covers multiple product lines with different efficiencies and warranties.
• Panel count — number of panels × watts per panel should equal system kW (e.g., 22 panels × 300W = 6.6kW).
• Watt rating — panels are rated in watts under Standard Test Conditions (STC). Higher watts per panel means fewer panels for the same system size.
• Efficiency — expressed as a percentage (e.g., 22.3%). Higher efficiency means more power from the same roof area.
• Product warranty — typically 10–25 years against manufacturing defects.
• Performance warranty — typically 25–30 years. Should specify that the panel retains at least 80–85% of rated output at end of warranty period.

Red flag: "Tier 1 panels" without a brand name is not a meaningful specification. "Tier 1" refers to a financial classification (manufacturers with bankable bonds) used by Bloomberg NEF, not a quality rating. Ask for the brand and model, not a tier designation.

Inverter

What to look for:

• Brand and model number — with the model, you can verify the specification independently.
• Inverter type — string inverter, hybrid (battery-ready), micro-inverter, or optimised (DC optimisers + string inverter). The quote should specify.
• Inverter size (kW) — for single-phase installations, maximum 5kW per Western Power rules.
• Warranty period — string inverters typically 5 years standard; some brands offer 10-year extended warranties.
• Monitoring platform — which app the inverter connects to, and whether real-time monitoring is included.

Red flag: An inverter brand you can't find online, no model number specified, or warranty described as "manufacturer's warranty" without specifying the term.

Installation inclusions

A complete installation quote should include:

• Rails and mounting hardware — on-roof or ballasted, material (aluminium, stainless fixings)
• DC cabling — from panels to inverter
• AC cabling — from inverter to switchboard
• Switchboard work — including any required isolators, protection devices, or circuit breaker upgrades
• Anti-islanding protection — AS4777.2 compliance (non-negotiable; required by law)
• Monitoring setup — connection of inverter to home WiFi, app configuration
• Signage — required under AS/NZS 5033 (fire switch labelling etc.)
• Western Power / network connection notification — your installer handles this, not you

Common exclusions to check: Scaffolding (older/steep roofs), switchboard upgrades (if your existing board is non-compliant), specific roof penetration work (tile roofs sometimes require additional waterproofing), or trenching for cable runs to a detached garage.

Performance estimates

Reputable quotes include:

• Annual energy production (kWh/year) — how much electricity the system will generate
• Self-consumption estimate — what proportion of generated solar you'll use vs export
• Savings estimate — calculated against your current usage and tariff

What to scrutinise: The assumptions behind the savings figure. A quote assuming 40% self-consumption when your household is empty from 8am–5pm is optimistic. Ask what assumption they've used for:

• Your current tariff (should be A1 at 33.26c/kWh from July 2026, not an older rate)
• Your daily usage profile (are you home during the day?)
• The export rate used for excess solar (2c for DEBS off-peak)

Red flag: Savings estimates that don't differentiate between self-consumption and export value. Every kWh self-consumed is worth 33.26c; every kWh exported off-peak earns 2c. A quote that values all generation at 33.26c will significantly overstate savings for a household that isn't home during the day.

CEC accreditation

What it is: The Clean Energy Council (CEC) accredits solar installers in Australia. Only CEC-accredited installers can access the Small Technology Certificate (STC) rebate, which typically reduces system cost by $1,500–$3,500.

What to check: The quote should include the installer's CEC accreditation number. You can verify it on the CEC website at solaraccreditation.com.au. If it's not listed, ask directly.

Why it matters: Beyond the rebate: CEC accreditation requires ongoing training and compliance with Australian Standards. An accredited installer is legally responsible for the installation's compliance with AS/NZS 5033 and AS4777. An unaccredited installer may do competent work, but you lose rebate eligibility and have reduced recourse under the framework.

Comparing multiple quotes

Once you have three quotes with full specifications, compare:

| Item | Quote 1 | Quote 2 | Quote 3 | |---|---|---|---| | Panel brand + model | | | | | Panel count × watts | | | | | Inverter brand + model | | | | | Inverter type | | | | | Inverter warranty | | | | | Annual generation (kWh) | | | | | Self-consumption assumption (%) | | | | | Total installed price (inc GST) | | | | | STC rebate applied (y/n) | | | | | Payment terms | | | |

The cheapest quote on price per kW of panels isn't always the cheapest quote on cost per kWh generated over the system's life. A system with higher-efficiency panels and a better inverter may produce 10–15% more electricity over 25 years on the same roof area.

Tariff rates referenced are effective 1 July 2026. STC rebate values vary by system size, location, and the current STC price — ask your installer for the current rebate figure applicable to your installation.