The floor: what 6.6 kW costs before anyone makes a dollar
Take the lowest price we could find on a public Australian trade list on 27 October 2026 for each thing a compliant 6.6 kW system must contain, add one day of award-rate labour and the unavoidable fees, add GST and take off the certificates. The result is $3,222 in Zone 3 (Sydney, Brisbane, Perth, Adelaide) and $3,472 in Zone 4 (Melbourne, Hobart, Canberra). It leaves out cable, isolators, conduit, the vehicle, insurance, a warranty provision, sales cost and any profit, so no business can sell at it. It is a floor, not a fair price. The national standard offer in the October 2026 index is $6,774, which is what a sustainable budget system costs.
| Line | Zone 3 (Sydney basis) | Zone 4 (Melbourne basis) |
|---|---|---|
| 15 panels, 6.6 kW, cheapest listed n-type panel at $0.365 per watt | $2,409.00 | $2,409.00 |
| 5 kW single-phase string inverter, cheapest mainstream unit on a public list | $1,090.11 | $1,090.11 |
| Tin-roof mounting kits and rails for 15 panels | $504.00 | $504.00 |
| Labour: one electrician and one installer, eight hours, award minimum, no super or travel | $477.76 | $477.76 |
| Certificate processing and connection or compliance fees | $43.33 | $58.03 |
| Subtotal before GST | $4,524.20 | $4,538.90 |
| GST at 10 per cent | $452.42 | $453.89 |
| Price before the STC discount | $4,976.62 | $4,992.79 |
| Less STCs at $39 each | 45 certificates, $1,755 | 39 certificates, $1,521 |
| Component floor after STCs | $3,222 | $3,472 |
In words: the panels are $2,409.00 ex GST, the inverter $1,090.11, the racking $504.00, the labour $477.76 and the fees $43.33 in Zone 3, a subtotal of $4,524.20; with GST the system costs $4,976.62 before the $1,755 STC discount. Zone 4 fees are $58.03 because Victoria charges for the electrical safety certificate, and the certificate count is lower, so the Zone 4 floor is $250 higher. Labour is the award minimum for two people for eight hours ($32.19 and $27.53 an hour all purpose); no crew is paid less lawfully, and most are paid more.
A $3,999 system against the floor
One widely advertised price for a fully installed 6.6 kW system is $3,999 after STCs, for unnamed panels and an unnamed 5 kW inverter on a single-storey home. Set it against the floor. In Zone 3 it leaves $777 above the cheapest compliant hardware and award labour; in Zone 4, $527. The minimum balance of system on the same trade list, one roll of PV cable, earth cable and four connector pairs, with no isolators, is about $345 including GST. After that the Zone 3 offer has $432 left for isolators, conduit, the vehicle, insurance, the warranty provision, the sale and the margin, and the Zone 4 offer has $182. The offer is $2,775 or 41 per cent under the national standard offer, and 0.61 dollars per watt against 1.03 for the standard offer and 0.49 at the floor. The cost per watt page has the bands by city.
The arithmetic does not say the offer is a fraud. It says the offer cannot be the hardware and labour the floor assumes, plus the things the floor leaves out, at that price. Something is different, and the next section lists what it usually is.
What gets swapped below the floor
A price under the floor is paid for by one of six substitutions. Each row names the floor item, what replaces it and the line on the quote that reveals the swap.
| Line | What the floor assumes | What replaces it below the floor | What to ask for |
|---|---|---|---|
| Panels | 15 x 440 W or 13 x 515 W, a listed n-type model at $0.365 per watt ex GST | A model that is not on the approved modules list, or fewer watts: 14 x 440 W is 6,160 W, 6.7 per cent less than 6.6 kW, and the STC count drops with it | Model number and wattage x count on the quote; the model on the approved list |
| Inverter | A 5 kW unit at $1,090.11 ex GST, the cheapest mainstream brand on a public list, with a 10-year warranty document | An unlisted brand with no Australian price list, no Australian service office and a shorter warranty | Brand, model and the warranty document, not the brochure |
| Racking | $504.00 of kits and rails from a mounting maker | Fewer rails and clamps than the mounting maker's layout calls for, or a kit not rated for the wind region | Mounting brand and a roof layout showing rails and clamp positions |
| Labour | $477.76 for two award-rate workers for eight hours | Piece-rate subcontracting, one person on the roof, or a day cut to half a day | The name and accreditation number of the person who will be on the roof |
| Compliance and connection | $43.33 in Zone 3: certificate processing and the network application | Nothing can be cut here; what is cut is the paperwork that goes with it | The network application reference and the electrical compliance certificate on completion |
| Balance of system | About $345 inc GST for cable and connectors alone; isolators, conduit and the inverter switch on top | Cable without conduit, missing isolators, no inverter isolation switch | An itemised line for isolators and conduit, or a written statement that they are included |
Two of these also move the subsidy. Panels or an inverter that are not on the Clean Energy Council approved lists cannot create certificates, so the $1,755 discount the quote shows would never be paid to the installer, and the shortfall becomes yours. A short system (14 panels sold as 6.6 kW) earns fewer certificates than the quote claims.
The STC line on a cheap quote
Check the STC line before the total. A 6.6 kW system earns 6.6 x 1.382 x 5 = 45 certificates in Zone 3, rounded down, and 6.6 x 1.185 x 5 = 39 in Zone 4. At $39 each that is $1,755 in Zone 3 and $1,521 in Zone 4; spot trades were within a dollar of $39 in the week before 27 October 2026. A quote that values the certificates 10 per cent or more below those figures is recovering money through the rebate line. A quote that values them above spot is advertising a discount it will not receive. From 1 January 2027 the deeming period drops to 4 years and the same system earns 36 certificates ($1,404) in Zone 3 and 31 ($1,209) in Zone 4; a cheap quote signed in December for a January install should say who wears that $351.
The warranty chain: three promises, three businesses
A solar system carries promises from three different parties, and a cheap quote usually blurs them into one word. The question that matters is which promises survive if the company that sold the system closes, because that is the failure a below-floor price makes more likely.
| Warranty | Who honours it | Typical term | Survives the retailer closing |
|---|---|---|---|
| Panel product warranty | The manufacturer | 15 to 25 years on the budget-tier datasheets we hold; up to 40 at the premium tier | Yes, if the maker has an Australian office or importer to claim through; a brand with no Australian presence is a warranty with no counter to take it to |
| Panel performance warranty | The manufacturer | 25 to 30 years | Yes, same condition; a claim needs an output test, which the retailer usually arranged |
| Inverter warranty | The manufacturer | 5 years standard on the Fronius-class unit (extendable), 10 on the budget-class unit, per the warranty documents | Yes, same condition |
| Consumer guarantees under the Australian Consumer Law | The retailer you paid | Not a fixed term; a reasonable period for the price paid | No: a guarantee against a company that no longer exists cannot be enforced |
| Workmanship warranty | The business whose installer did the work | Whatever the quote states, in years | Only if the installing business is a separate entity that is still trading; if the retailer subcontracted, ask for the installer's name in writing |
So the two warranties worth the most on a cheap system are the ones that do not depend on the seller: the panel and inverter manufacturer warranties, which only have value if the maker has an Australian presence, and the workmanship warranty, which only has value if the installing business is named and still exists. The next three sections are how to check each.
Check the person on the roof: the Solar Accreditation Australia register
Only a system installed by an accredited installer can create certificates, so the accreditation is what makes the $1,755 discount real. The retailer's accreditation is not the installer's, and the salesperson's is not either. Before the install date, ask for the name and accreditation number of the person who will be on your roof, then check it at saaustralia.com.au/accreditation-status-check/. The page takes either the accreditation number or the installer's first and last name. If the company will not give you a name until the morning of the job, that is the answer. For a battery the same installer needs a battery endorsement on the accreditation.
Check the hardware: the Clean Energy Council approved products lists
The Clean Energy Council keeps three lists: approved PV modules, approved inverters and power conversion equipment, and approved batteries, at cleanenergycouncil.org.au/industry-programs/products-program. Certificates can only be created for listed products. Match the exact model number on your quote, not the brand: a brand can have listed and unlisted models side by side. The lists change, and a product can be removed at any time, so check on the day you sign and keep the result. A quote that gives a brand and a wattage but no model number cannot be checked and should be sent back.
Check the company: ABN Lookup and the registration date
Search the company name or the ABN printed on the quote at abr.business.gov.au. Read four lines. ABN status reads "Active from" followed by a date: that is the day this legal entity was registered, and it is the number to hold against a ten-year workmanship warranty. Entity type tells you whether you are dealing with a company, a sole trader or a trust. Goods and Services Tax reads "Registered from" with its own date. Business names are listed with a "From" date each: an old-sounding brand with a recent business-name date on a recently registered ABN is a new entity trading under a familiar name, which is how a workmanship warranty from the previous entity disappears. Make sure the ABN on the quote, the invoice and the receipt is the same one.
What a cheap quote worth taking looks like
Cheap and sound are not opposites. The standard offer in the October 2026 index is $5,294 in Perth and $5,812 in Adelaide, against $6,170 in Sydney and $6,218 in Melbourne. A quote near those figures on a single-storey tin roof with budget-tier panels named by model, a mainstream inverter named by model, a named accredited installer, an STC line within 10 per cent of $1,755 or $1,521 for the zone and an ABN that has been active longer than the workmanship warranty is a cheap quote. A quote $2,775 under the standard offer with none of those things is a cheap price. The quote check runs the price and STC tests for your city, and the cost pillar has the full index.
Cheap solar per kWh over 25 years
A 6.6 kW system in Sydney makes about 221,388 kWh over 25 years at 1,424 kWh per kW a year with 0.5 per cent annual degradation. At the standard offer of $6,774 that is 3.1 cents per kWh; at $3,999 it is 1.8 cents; at the Zone 3 floor it would be 1.5 cents. The whole saving from buying at $3,999 instead of the standard offer is 1.3 cents per kWh, if both systems run for 25 years. The risk on the cheap system is not the 1.3 cents. It is the 221,388 kWh: a system that stops producing, with nobody left to fix it, costs its full price for whatever it made before it stopped. Against a grid rate of 34 cents in New South Wales, a sound system at the standard offer is already cheap.
Cheap solar questions
How cheap can a 6.6 kW solar system be?
$3,222 in STC Zone 3 and $3,472 in Zone 4 is the component floor in October 2026: the cheapest listed panels, inverter and racking at trade prices, one day of award labour, fees and GST, less STCs at $39. It excludes cable, isolators, insurance, a warranty provision and margin, so a real quote has to be higher. The national standard offer is $6,774.
Is a $3,999 solar system legitimate?
$3,999 is $777 above the Zone 3 component floor and $527 above the Zone 4 floor, which has to cover cable, isolators, conduit, insurance, the warranty provision, the sale and the margin. It is $2,775 under the national standard offer. The price can only work if one of six things is swapped: panel model or count, inverter brand, racking, labour, balance of system or the paperwork. Check the model numbers, the installer's accreditation and the ABN before judging it.
What is cut in a cheap solar system?
6 things, in the order they usually go: panels not on the approved list or fewer watts than claimed (14 x 440 W is 6,160 W, 6.7 per cent short), an unlisted inverter brand, racking below the maker's layout, labour below the $477.76 award minimum for two people for a day, cable without conduit or missing isolators, and the connection paperwork.
Who honours the warranty if the solar company closes?
3 parties gave you promises. The panel and inverter manufacturer warranties survive if the maker has an Australian office or importer. The workmanship warranty survives only if the business whose installer did the work is a separate entity still trading. The consumer guarantees you held against the retailer die with it.
How do I check if a solar installer is accredited?
1 search at saaustralia.com.au/accreditation-status-check/: enter the accreditation number, or the first and last name, of the person who will be on the roof. Ask for it before the install date. The company's accreditation does not count; only an accredited installer can create the $1,755 in certificates a Zone 3 6.6 kW quote relies on.
How do I check how long a solar company has existed?
1 search at abr.business.gov.au by name or ABN. The ABN status line reads "Active from" and a date: that is when this legal entity was registered. Compare it with the workmanship warranty length, read the entity type, and look at the business names and their "From" dates for an old brand on a new registration.