Solar Choice Solar & Battery Storage Sizing & Payback Calculator

solar_choice_logo_finalsolar_choice_logo_finalWith demand for solar battery storage in Australia growing quickly, Solar Choice has developed the below Solar PV & Battery Storage Sizing & Payback Estimator tool below to help Australian households & businesses to make a decision about whether to install a solar PV system, a battery storage system or both.

However, it’s important to keep in mind that all calculator outputs are indicative only. They are not intended to take the place of advice from an industry professional based on a more detailed assessment.

While we’ve made every effort to make sure that this calculator is as accurate as possible (given its inherent limitations), but there may still be some glitches that have slipped through the cracks – let us know.

If you’d like a more detailed assessment of your property’s solar potential, get in touch with Solar Choice via email, phone (1300 78 72 73), or fill out our Solar Quote Comparison Request form.

Looking for a more detailed analysis?

Additionally, Solar Choice’s commercial solar engineering team has a highly sophisticated solar & battery return on investment modelling tool for our internal use. If you are a commercial client who is thinking about investing in solar and batteries for your business, please reach out to us directly for a more accurate indicative business case. Matt Lasauce is our Commercial Tender Manager – he can be contacted on matt@solarchoice.net.au

Some notes about using this estimator:

1. This calculator has the following limitations

  • All outputs from this calculator are based on a 24-hour period, using the average of one year of solar data. (More sophisticated tools would use a full 365 days of data.) As a result, all results should be viewed as ‘ball-park’ figures to be checked against other sources. It also doesn’t take into account seasonal variance in energy consumption or solar output, or the different way that a home might use energy on weekends.
  • All financial calculations are based on fairly simple calculations and should be seen as indicative only. Outputs do not constitute recommendations or advice. Again, we recommend that you check the results from our calculator against those from other sources.
  • Currently, the calculator only works for Australia’s capital cities.
  • For the most part, battery degradation is not modelled in this calculator. The only exception is in calculating battery payback times, where we assume that the battery bank will operate for the first half of its life at 100% capacity and the second half of its life at 80% capacity.
  • Battery charge and discharge efficiency are not modelled either. Instead, we have a more general input field for ‘battery efficiency’.
  • The calculator assumes that the battery bank can always ramp up to meet household energy demand. This may not be the case in real life. It’s far more important to have a battery bank that can respond quickly to sudden increases in demand if you have an off-grid system. For grid-connected systems, the electricity grid will meet any excess demand not met by solar/batteries.

We recommend cross-checking the results against those of other tools that are available online (keeping in mind their own limitations):

2. Enter values into the white boxes (only!) 

Depending on your web browser, when you click on the calculator you will automatically jump to the top of the screen (a glitch we are working to iron out). After you first click, use your keyboard arrows to move between boxes. The box you are currently editing will be highlighted.

The solar ROI calculator is designed to give you a set of outputs based on the details that you include. Changing the values in any of the coloured boxes will disrupt the formulas; if you do this by accident, simply refresh the page in your browser to start over.

The output values will change automatically as you enter your details in the white boxes–no need to hit any ‘submit’ buttons.

If you want to start over for any reason, simply refresh the page.

3. Try different combinations of sizes, prices and specifications

Our calculator is not designed just to spit out one set of answers, but rather to allow you to explore a range of possibilities and how they pan out. You’ll need to provide inputs of your own to make it relevant to you.

Below we’ve listed some resources for you to use to collect these inputs – otherwise you can just estimate them.

Energy usage & pricing

  • Your energy bill is the best place to get your energy usage & price data – there should be a chart on the back that shows your historic energy consumption by month. (N.B. Our calculator does not account for fixed supply charges.)
  • The federal government’s EnergyMadeEasy website is a great place to compare energy pricing offers from suppliers in your area

Solar PV system & battery pricing

  • Solar Choice publishes monthly articles about solar system price trends in Australia’s major cities–for both commercial and residential solar systems. You can also request a Solar Quote Comparison to get current pricing on solar systems of a range of sizes in your area.
  • There is not currently a reliable, publicly available, ‘one-stop’ source for battery pricing data in Australia. In addition to solar system prices, you can also compare battery storage system pricing by requesting a Solar Quote Comparison by filling out the form to the right of this page.
  • Ball-park figures for a fully installed battery storage system are $1,000-$1,500 per kilowatt-hour (kWh) for lithium-ion and $500-$1,000 for lead acid.

Comments or feedback about this calculator?

We’d love to hear from you. Email us at james@solarchoice.net.au.

Get started! Choose the version of the calculator that best suits your situation

Which of the following best describes your situation? Click on one of the links.

I want to explore all of my options – including grid-connected and off-grid systems

I want to see how much I can save with a grid-connected solar plus storage system

I want to retrofit a battery bank onto an existing grid-connected solar system

I want to explore whether going off-grid with solar & storage is an option for my home

If you’re only looking for solar, you might want to check out our Solar Power System Payback & ROI Calculator, which offers slightly more detailed (but still indicative) financial analysis. Additionally, if you know that you’re not interested in battery storage, our Simple Solar PV System Sizing Estimator Tool can help you determine what size of solar PV system you need.

We also have an ‘advanced’ version of our Solar PV & Battery Storage System Sizing & Payback Estimator. The advanced tool does not have instructions, and has a wider range of inputs and outputs. The version below is a streamlined version of the advanced calculator.

Solar Choice’s Battery Storage Sizing & Payback Estimator (Full version)