Solar payback estimates range from “5 years” to “15 years” depending on who you ask. Most of that variance comes from assumptions about the variables below. Here's what actually moves the needle — and what doesn't.
The Key Variables
Self-consumption rate
High impactThe most important variable. Electricity you use directly from your solar replaces grid purchases at ~30 cents/kWh. Electricity you export earns ~5 cents/kWh. A 10% improvement in self-consumption can reduce payback by 1–2 years.
System size vs your usage
High impactAn oversized system generates more electricity than you can self-consume, pushing more to the grid at low export rates. A right-sized system maximises self-consumption and improves payback. This is why sizing from your real data matters.
Feed-in tariff rate
Medium impactVictoria's minimum feed-in tariff varies year to year. As of 2025, rates are generally 4–6 cents/kWh. Export earnings are significant if you have a large system and low self-consumption, but they'll never match the value of self-consumed solar.
Electricity purchase price
High impactHigher electricity prices mean solar saves more money per kWh self-consumed. Electricity prices have risen significantly in Victoria over the last few years — this generally improves solar payback.
Roof orientation
Medium impactNorth-facing is optimal in Australia. East/west orientations generate less total energy but spread generation more evenly across the day — which can actually improve self-consumption for households with morning and afternoon peaks.
Shading
Variable impactEven partial shading on one panel can significantly reduce system output depending on your inverter/panel technology. A site assessment identifies shading issues before they affect your payback.
Solar resource (location)
Low-medium impactBendigo receives more solar irradiance than Melbourne. Regional Victoria generally performs well for solar. This is factored into our modelling using specific local data.
What HEA Targets
Our target on every installation is a payback period under 10 years. For many Bendigo households — especially those with significant daytime usage — payback in the 6–8 year range is achievable with a well-sized system.
We don't use industry average assumptions for our proposals. We use your real interval data, current Victoria feed-in tariffs, and your actual electricity plan rates. We tell you what the assumptions are — so if prices change, you can update the estimate yourself.
Get a payback estimate for your home
We build our proposals from your actual Powercor data and current Victorian rates. No generic averages. No assumptions you can't check.
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