Solar & Battery Savings Calculator

Our calculator uses real Perth electricity rates (Synergy), current rebate values, and industry-standard efficiency assumptions. For the most accurate results, enter your actual daily usage from your electricity bill and use the 'Custom System Price' feature with your installer's quote.

Add Battery (existing solar): Calculate savings from storing your excess solar instead of exporting it. Solar + Battery (new system): Plan a complete new installation with both solar panels and battery storage.

Yes! Your calculations, shortlisted batteries, and comparisons are automatically saved in your browser. You can return anytime to pick up where you left off. For advanced features like PDF exports, create a free account.

Our guided wizard includes average Perth household defaults. You can also check your Synergy bills for actual usage, or start with estimates and refine later. The calculator shows how different usage patterns affect your results.

For most Perth homes with 10-13kWh batteries, the capacity taper in force since 1 May 2026 has minimal impact—batteries under 14kWh retain full STCs. For larger systems (14-28kWh) the federal rebate is now around $1,500-2,500 less than under the pre-May rates. Right-sizing the battery to actual household consumption typically delivers better ROI than chasing maximum capacity.