YOUR HOME / THE STARTING POINTMelbourne solar and battery size calculator.
A simple starting point for solar, inverter and battery size based on your household.
No name, street address, email or phone number needed. Your answers stay in this browser tab unless you choose to submit a quote request.
Prefer to start with your appliances? Build your household →
HOW THE CALCULATOR WORKSA planning model, not a roof-specific solar design.
The calculator turns household electricity use into a practical starting range for solar, inverter and battery capacity. It deliberately separates the household-energy question from the final installation design: roof space, shading, switchboard condition, distributor approval and exact equipment still need property-specific checks.
1. Household demand comes first
If you enter average daily kWh from a bill, that measured figure takes priority. If you do not know it, household size, bill range and the optional household builder provide a broad fallback estimate.
2. Solar is compared with Melbourne generation
Introductory solar scenarios use an annual-average Melbourne benchmark of about 3.6 kWh per installed kW per day. Seasonal output and the real roof can differ materially.
3. Batteries follow later-day demand
Battery examples are driven mainly by electricity used after strong solar-production hours, not by a rule that the battery must match the solar-array size. Existing exports and selected grid-charging opportunities also matter for homes that already have solar.
4. Inverter size is a separate decision
The inverter recommendation is qualified by single-phase or three-phase supply, existing equipment and the system pathway selected. Network limits and an electrical design still determine what can actually be approved and installed.
A simple worked example
Suppose a household uses about 24 kWh a day, with roughly 10 kWh used later in the day. The calculator first compares solar capacity with the 24 kWh daily demand, then compares battery examples with the later-day requirement. If the household already has solar, measured generation and exports can change the answer. If an EV, heat-pump hot water or electric heating is planned, the future-proofed option can add a modest amount of headroom rather than automatically jumping to the largest system.
How projected bill savings are estimated
The results use an illustrative import-price range of 25–35¢/kWh and an export value of 0–5¢/kWh. Supply charges are excluded because they generally remain payable. The range is intentionally broad because retailer tariffs, self-consumption and battery operation can move the outcome substantially.
How the Midday Power Saver is treated
If you choose to include Victoria's three-hour midday option, the model treats free grid imports as a possible charging opportunity, not as unlimited battery energy. Household use, charging power and the applicable daily allowance still constrain how much energy can reach the battery.
Calculator FAQs
Is the recommended solar size a quote?
No. It is an educational starting point. A quote should confirm the usable roof area, shading, electrical work, exact equipment, distributor requirements and current incentives.
Do I need to know my exact electricity usage?
No. The calculator can use broader household assumptions, but a recent bill or interval data will usually improve the recommendation.
Why can the battery be larger or smaller than the solar system?
Solar capacity is expressed in kW while battery storage is expressed in kWh. They solve different problems. Battery capacity is primarily about how much energy needs to be shifted into later hours or held for backup.
What if I already have solar?
The calculator can retain the existing system and compare battery-first or upgrade pathways. Measured generation, imports and exports are much more useful than assuming the current panels must automatically be replaced.
Battery sizing guide ↗·Single vs three phase ↗·Compare solar quotes ↗