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Solar payback calculator (Australia)

Estimate payback, annual savings and ROI from bill data, system size, feed-in tariff and optional battery. See all energy tools via the links below.

Results are estimates for guidance only. InFront Tech is not responsible for any reliance on these tools. Confirm figures with your installer or provider.

Solar & battery

Solar Payback Calculator (Simple)

Estimate payback period, annual savings and ROI. System size, power bill, feed-in tariff and battery option.

Use this tool

Battery Backup Sizing Tool (Home / Business)

Size a battery and inverter for key devices. Pairs well with UPS and backup power planning.

Use this tool

Solar · Payback · Australia

Solar Payback Calculator

Comprehensive payback and savings estimate. Enter your current bill, usage, system cost and rates. Includes battery and rebates.

Answer the questions below using your latest bill and a quote (or estimates). Results are indicative; confirm with your installer.

Your bill & system inputs

Bill-first mode: use your bill wording. Enter amount due (or bill total), bill period days (usually ~90), general usage kWh for that same period, and daily supply charge. We annualise automatically.

Required inputs

Q1) Bill amount and period
Use “Amount due” or “Total new charges incl. GST” for this bill period. Example: $743.51 for 90 days.
Use the exact bill period shown on your invoice (e.g. 90 days). This is used to annualise all values fairly.
Use the “General usage” kWh line for the same bill period (not exports). Example: 3,442 kWh.
This is the fixed daily network/retailer charge (often listed as Supply charge Daily). It applies even if usage is low.
Optional. If unknown, leave blank and we estimate from your bill amount, usage and supply charge.
Q2) How your usage is split through the day
This is your daytime load share. Higher % means you use more solar directly and export less. Typical homes: 25–45%.
Show advanced assumptions (optional)

System assumptions

Q3) Solar generation settings
From your installer quote (panel array size). Typical homes are often 6.6 kW to 13.2 kW.
Choose your location to estimate average daily sun. This drives annual solar generation.
Performance factor after real-world losses (heat, inverter, dirt, wiring). 0.85 is a common default.
Q4) Upfront system costs
Enter quoted system price before rebates. Leave blank to use default estimate per kW.
Any STC/government/retailer discount that reduces your out-of-pocket upfront cost.

Optional battery and tariff settings

Q5) Battery assumptions (optional)
Q6) Rates after solar

These are the tariff settings your retailer applies after solar is installed. They determine your new bill calculation.

Credit rate for each kWh exported to the grid. Check your plan’s “solar export” or “feed-in tariff” rate.
This is still your fixed daily network connection fee after going solar (you pay it even with zero usage). It is often the same as your current supply charge unless your plan changes.

Payback & savings

Why use this solar payback calculator?

  • Estimate solar payback period, ROI and long-term savings before you commit to a quote—using bill-first inputs that match real Australian electricity invoices.
  • Compare 10-year and 25-year outcomes side by side to discuss value with family or finance—not just the sticker price per kilowatt.
  • Model feed-in tariff, retail usage rates, daily supply charge and how much energy you use in daylight vs evening—drivers of real solar savings.
  • Toggle battery and rebate-style adjustments to see how add-ons change the business case—useful when comparing installer packages.
  • Pick sun hours by region (Brisbane to Hobart) so production expectations fit your roof location.
  • Transparent assumptions you can review with an accredited designer—supplements, not replaces, professional advice.
  • Ideal for households and small business exploring rooftop PV, feed-in credits and lower grid imports.
  • Sanity-check solar payback, annual savings and battery add-ons against the numbers on your bill and your installer quote—before you sign.

Battery · Backup · Sizing

Battery Backup Sizing Tool (Home / Business)

Size a battery and inverter for backing up key devices. Pairs well with UPS and backup power planning.

Enter the total wattage of devices you want to run during an outage and how long you need them to run. We estimate battery size, inverter size and a typical cost band.

Load & runtime

Add up the watts of fridge, lights, modem, etc.
How long you need backup for

Sizing estimate

Why use this battery backup sizing tool?

  • Turn a list of devices (fridge, lights, modem, medical equipment) into a rough battery kilowatt-hour and inverter kilowatt target before you request quotes.
  • Match required runtime hours to outage goals—storm backup, rural reliability or overnight essentials—not a random guess.
  • See a typical cost band so you can budget discussions with electricians and battery retailers.
  • Pair with solar planning: understand backup load separate from daily self-consumption maths.
  • Complement UPS sizing for offices and retail where network gear and POS must stay online briefly.
  • Clarify watts vs hours: the tool makes the energy (kWh) implication of your wattage explicit.
  • Useful for Australian home and small business owners comparing generator vs battery strategies at a high level.
  • High-level answers to how much battery you need, what inverter headroom matters, and how runtime hours scale with load—before detailed engineering.

Results are estimates. Use as a design guide only; InFront Tech will not be responsible for any reliance on these tools or results.

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