Longi solar panels in Perth: what to know about the world's largest manufacturer

Longi is a solid mid-tier choice for a Perth rooftop. You get a 15-year product warranty, a 25-year performance warranty down to 84.8% of rated output, and a 0.55%/year degradation rate that beats the industry baseline. For a 10kW system after STC discounts, a Longi-based quote typically lands around $9,000 to $12,000, usually a few hundred to a thousand dollars under the equivalent Trina build. The trade-off: you are not buying the absolute best per-panel output or temperature performance on the market. If budget matters but you want better than entry-level warranty terms, Longi fits.

Here's the detail behind that, and how Longi stacks up against the other brands Perth installers quote.

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Who makes Longi panels?

Longi (full name LONGi Green Energy Technology Co., Ltd) was founded in China in 2000 and listed on the Shanghai Stock Exchange in 2012. They pioneered high-efficiency monocrystalline silicon manufacturing at scale and pushed the whole industry toward mono PERC cells. They are consistently ranked the world's highest-volume solar panel manufacturer.

That size matters for one practical reason: a large, publicly listed manufacturer is more likely to still be around honouring a warranty claim in 15 years than a smaller or newer brand. Longi runs an Australian operation (LONGi Solar Australia) that handles warranty claims and technical support for the local market.

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Which Longi panels get installed in Perth?

Three series turn up in most Perth quotes:

Hi-MO 5 (LR5 series). Monocrystalline PERC in the 400 to 450W range. This is the most common Longi product on Perth residential roofs. It uses half-cut cells, which lower resistive losses and handle shade better than full-cell modules.

Hi-MO 6 (Explorer series). Longi's back-contact panel, built on HPBC (Hybrid Passivated Back Contact) cells rather than PERC. Power output runs roughly 415 to 470W. It is increasingly common as the Hi-MO 5 phases out.

Hi-MO X6. Also HPBC back-contact technology, sitting at the higher end of Longi's residential range. Slightly better efficiency and a lower temperature coefficient than the PERC panels.

One label to get right: Longi's premium cells are HPBC, a back-contact design. They are not TOPCon. Some quotes and spec sheets blur this, so if the technology matters to your decision, check the exact model number against the datasheet.

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How do Longi panels perform in Perth heat?

Perth roofs get hot, and a panel's temperature coefficient tells you how much output it sheds as cell temperature climbs above 25°C. Lower is better.

• Hi-MO 5/6 PERC: approximately -0.34%/°C. Typical for PERC, with no meaningful difference from comparable PERC brands.
• Hi-MO X (HPBC back-contact): approximately -0.29%/°C. Slightly better than PERC, which narrows the gap with REC Alpha (-0.24%/°C) without closing it.

At a 65°C cell temperature, common on a Perth summer afternoon, a PERC panel produces roughly 12% below its rated output. The back-contact panels lose a little less.

The half-cut cell design helps here too. If one row of half cells is shaded, only half the panel drops out instead of the whole module. That is a real benefit on Perth roofs where vents, antennae, or early-morning shadows clip part of an array.

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What warranty do Longi panels come with?

Two numbers do the heavy lifting. The 0.55%/year degradation rate sits in line with other leading PERC panels (typically 0.54 to 0.55%/year) and well under the industry baseline of around 0.7%/year. And the 84.8% guaranteed output at year 25 is a strong floor for this tier.

On warranty service: Longi Australia handles claims, though its Australian footprint is smaller than the global market share might suggest. The practical step is the same one you would take with any brand. Confirm your installer's Longi warranty-claim pathway before you sign, so you know who lodges the claim and how if a panel underperforms.

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How much do Longi panels cost in Perth?

Longi sits in the value end of the bankable-brand segment: a step up from unbranded or generic modules, and priced below premium names like Trina and REC Group.

Here is a rough 10kW comparison after STC discounts:

• Longi Hi-MO 6 with a Sungrow inverter: approximately $9,000 to $12,000
• Trina Vertex S+ with a Sungrow inverter: approximately $10,000 to $13,500
• REC Alpha with a Fronius inverter: premium pairing, materially higher again

Longi typically comes in $500 to $1,500 under a Trina Vertex S+ build of equivalent specification. That gap is the main reason Longi shows up so often in cost-competitive Perth quotes. These are indicative ranges, not fixed prices: your number depends on roof complexity, inverter choice, and the installer.

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Longi vs Trina vs generic Tier-1: how do they compare?

Longi's edge over the cheaper value brands comes down to two things: the stronger 0.55%/year degradation warranty against a typical 0.7%, and the company's scale and longevity. A panel warranty is only worth as much as the company standing behind it, and a manufacturer this size is a safer bet over a 25-year horizon. Note that the cheaper brands are not uniform. Canadian Solar's Australian KU range, for instance, also guarantees 84.8% at year 25, on par with Longi, so check the specific model rather than the category.

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When does Longi make sense for a Perth home?

Longi is a sensible pick when:

• You want a mid-market panel with a strong degradation warranty at a competitive price.
• Your installer has a solid Longi supply relationship and a warranty track record.
• You have enough roof space that squeezing maximum output from each panel is not critical.
• Budget matters, but you want better than entry-level quality.

Look at Trina Vertex N or REC Group instead if:

• Roof space is tight and you need maximum output per panel.
• You want a brand with a longer track record of Australian warranty service.
• You will pay a modest premium for Trina Vertex N's higher per-panel efficiency or REC Alpha's better temperature performance.

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Related reading

• Longi vs Trina solar panels in Perth, a head-to-head on the two value Tier-1 brands Perth installers quote most.
• PERC vs TOPCon vs HJT panels, a plain-language breakdown of the cell technologies behind these brands.
• REC Group solar panels in Perth, the premium alternative with best-in-class temperature performance.
• Jinko and Canadian Solar in Perth, where the cheaper value brands actually land on warranty and quality.
• The best solar panels for Perth in 2026, the pillar guide ranking the brands by use case and budget.
• The "Tier 1" panel myth, why "Tier 1" is a bankability ranking, not a quality grade.