A panel's temperature coefficient states how much power drops for each degree above the 25°C test cell temperature — often around −0.3%/°C for modern modules. On Australian summers, cell temperatures of 60°C+ are common on dark roofs, so real output sits well below nameplate even at noon. This spec separates marketing peak watts from February reality.
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A −0.30%/°C coefficient means roughly 0.3% less power per degree above 25°C. A 40°C rise implies about 12% less power before other losses. Closer-to-zero coefficients (e.g. −0.26%/°C) lose less in heat.
High irradiance arrives with high ambient temperatures inland and on metal roofs. Perth, Adelaide and western Sydney summers are classic examples where temperature coefficients matter in brand comparisons.
Allow roof standoff for airflow, avoid trapping heat in poorly ventilated trays, and consider lighter roof colours where renovating. Microclimates under modules are part of yield engineering.
Hot cells lower voltage/power; cold clear mornings can raise voltage. Designers must keep string voltages inside inverter windows across seasons — another reason CEC-accredited design beats DIY string maths.
Storage shifts energy in time; it cannot recover power the array never generated at 2pm in a heatwave. Still valuable for evening tariffs under ~$372/kWh usable support, but separate from module thermal behaviour.
When two modules are close in price, prefer the kinder temperature coefficient if your site is hot and space-constrained. MrSolar quote comparisons should include datasheets, not only brochure efficiency.
Compare modules on heat behaviour, not just watts — review CEC-accredited quotes on MrSolar.
Written and reviewed by Daniel (Marketplace lead, Epic Unicorn Pty Ltd). We build pages from Australian solar datasets and regulatory references, then map you to CEC-accredited installers only.
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