Reading a solar quote: what "fully installed" doesn't always cover

Two solar quotes for what looks like the same size system can land thousands of dollars apart, and the gap rarely comes down to one installer simply being greedier than another. It usually comes down to differences in the components specified, the scope of work actually included, and what has quietly been left out of the number at the bottom of the page. Reading a quote properly means pulling those pieces apart rather than comparing two lump sums.

Start with the panels. Marketing material often talks about panel "tier", a ranking thrown around as though it were a quality grade, when it is really closer to a rough indicator of a manufacturer's financial scale and bankability rather than a guarantee of superior output or longevity. A lower-tier panel from a well-established manufacturer can genuinely outperform a higher-tier one over its lifetime, and efficiency, warranty terms and the manufacturer's actual track record in Australia tell you more than the tier label alone. Ask specifically which panel model is quoted, not just the brand name, since a manufacturer often sells several ranges at different price and quality points.

The inverter deserves just as much scrutiny, and the choice between a string inverter and microinverters or power optimisers changes how the system behaves, not just its price. A string inverter is the cheaper, more common option, wiring panels together in series so the whole string's output drops to match the weakest-performing panel, which matters if part of your roof gets shaded at certain times or if panels face more than one direction. Microinverters, and the middle-ground option of power optimisers paired with a string inverter, let each panel perform independently, usually costing more upfront but worthwhile on a roof with genuine shading or multiple orientations, and adding little value on a simple, unshaded roof facing one way.

System size is its own decision, and the 6.6-kilowatt system built around a 5-kilowatt inverter has remained a common default for years, partly because it sits within the oversizing ratio the industry permits and partly because a 5-kilowatt inverter aligns neatly with the export limits many networks set for single-phase homes. Export limits vary by state, network and phase, and some networks are moving toward flexible limits that change through the day, so ask your installer what export limit actually applies at your address rather than assuming a figure from a website written for a different state.

"Fully installed" is the phrase most worth interrogating, because it means different things at different firms. Ask whether the price includes any switchboard upgrade the system might trigger, a meter upgrade to allow export, scaffolding for a steep or multi-storey roof, extra mounting rail for tile versus tin roofing, and a monitoring app or dongle so you can see what the system is producing once running. Any of these can turn up as an addition once work begins, turning an attractively low headline figure into a considerably higher final invoice.

Overall system cost varies with location, roof complexity and component quality, and published figures move from source to source and change over time as the federal rebate steps down each year, so treat any specific number you read, including elsewhere on this site, as a starting reference rather than a firm quote. Getting at least three itemised, like-for-like quotes, specifying the same panel model, inverter type and scope of work, is the most reliable way to see what a fair price looks like for your home. Our directory lists solar installers by area if you are ready to compare quotes.

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