The calculator uses postcode-level solar irradiance data, current Australian electricity tariff ranges, and verified system output figures from Sunflare's 1,000+ installs. For most homes, the estimated saving is within 10 to 15 percent of actual first-year performance. The primary variable the calculator cannot account for is shading, which is assessed during the site visit.

The right size depends on your quarterly bill, your daily usage pattern, and your roof orientation. For a four-bedroom home in Melbourne's western suburbs with a bill between $300 and $400 per quarter, a 6.6kW system is typically correct. Homes with pool pumps, ducted heating, or planned EV charging generally suit 9.9kW.

The payback period for a 6.6kW system in Victoria ranges from 4 to 7 years depending on your consumption profile, roof orientation, and the final net system cost after rebates. The Solar Victoria rebate of up to $1,400 and the STC discount both reduce the payback period materially. Sunflare provides a payback period calculation with every quote.

Yes, in the context of Victoria's current feed-in tariff. Victoria's 2025-26 feed-in tariff was set at 0.04 cents per kWh. Storing that energy in a battery and using it at peak evening rates instead can add $400 to $800 per year in additional savings on a typical 10kWh battery system. Sunflare confirms your eligibility on the first call.

Based on Sunflare's residential VIC installs, the median quarterly bill reduction for a correctly sized system on a north-facing roof in Melbourne's western suburbs is from $390 to under $60 within the first billing cycle. Annual savings range from $1,200 on a 6.6kW system to $1,900 or more for higher-consumption households on a 9.9kW system.