Kilowatt peak (kWp) measures a solar array's DC capacity under standard test conditions — the headline “6.6kW system” number on Australian quotes. It is not the same as instantaneous AC output or daily kilowatt-hours. Knowing the difference stops you from comparing incompatible quotes and misreading STC discounts.
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Indicative 2026 pricing: a typical 6.6kW system often quotes around $5,000–$8,000 after the STC discount (metro installs often $5,000–$7,500; premium/regional can run higher). See our solar cost guide.
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Module ratings assume 1000 W/m² irradiance, a defined spectrum and 25°C cell temperature. Real Australian roofs run hotter and see varying sun, so you rarely see continuous kWp at the meter. Temperature coefficients explain part of the gap on 40°C summer afternoons.
Designers may pair a 6.6kWp array with a 5kW AC inverter (a common residential pattern historically) or match them more closely. DNSP export limits often refer to AC capacity. Ask which number your network application uses.
STC calculations scale with installed eligible kW (with zone and deeming). In 2026, a Zone 3 6.6kW system is worth about $1,435 at MrSolar's ~$39.85 spot reference (as of 5 August 2026). Misstated kWp on a quote misstates the federal discount.
Modern ~400W panels need roughly 15–20 panels for 6–8kWp depending on wattage. Orientation, setbacks and shade shrink usable area. kWp is meaningless if the roof cannot host the modules safely under AS/NZS 5033 practice.
Daily energy ≈ kWp × peak sun hours × system efficiency factors. Sydney near 5.0 peak sun hours suggests a well-installed 6.6kWp array often lands around the mid-20s to low-30s kWh/day before losses — not 6.6kWh. Use city-specific estimates on quotes.
When you request three CEC-accredited quotes via MrSolar, lock the target kWp range first. Then compare panel wattage, inverter AC rating, export assumptions and price after STC — not marketing adjectives.
Compare like-for-like kWp quotes from CEC-accredited installers 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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