Solar Panel Calculator: Calculate your solar payback period

Image of a calculator on a solar panel representing the concept of saving energy with renewable energy

Solar Choice has created a payback and return on investment (ROI) calculator to assist households all over Australia in determining whether to switch to solar energy. Going solar is a smart investment that can lead to a significant decrease in your electricity bills. We have put in a lot of effort into developing this solar panel calculator and would appreciate any feedback you may have.

It is important to note that the inputs and outputs below are indicative only. It does not take into account exactly how your home or business uses electricity throughout the day, the tilt & orientation of your roof, total system efficiency, or whether or not you would have any shading on your panels.

Are you looking for our Commercial Solar Payback Calculator?

If you’re interested, here are some notes on our calculations!

  • Sunlight hours are estimated based on data from Our assumptions for average per day Sunlight hours are Adelaide – 4.84, Brisbane – 5.16, Canberra – 4.78, Darwin – 5.92, Hobart – 3.83, Melbourne – 4.18, Perth – 5.34, Sydney – 4.54
  • GST is not charged on exported solar from residential systems
  • The solar panel calculator automatically adds 10% GST on retail electricity tariffs
  • We have assumed an overall system efficiency of 75% which is a conservative estimate
  •  ‘Years to pay off’, ‘Annual IRR’ and ‘System NPV’ output values all account for gradual panel degradation (from 97% of output based on nominal capacity in year 1, to 82% in year 25, as per panel manufacturer best practice.
  • This calculator works only for flat-rate tariffs. We are currently looking into building a similar tool for time of use and block tariffs.
  • At present, the calculator does not account for fixed daily ‘supply charges’ or electricity retailer discounts (e.g. ‘pay on time’ and ‘direct debit’ discounts).

Find out solar panel calculator helpful? Support Solar Choice by leaving us a review 

Compare quotes from up to 7 installers in your area now.

Want a better Return on Investment?

We have written previously about how to get the most out of a solar PV system. Given the low value of excess/exported solar power in Australia (with rates in most states around 6-8¢/kWh), it is key to make sure that you’re consuming as much of the solar power your system produces as possible (read more about ‘solar self-consumption‘).

You should also be aware of how much you’re paying for grid electricity (‘Cost of retail electricity’) if you’re not sure or are considering switching your electricity retailer or tariff anyhow, visit the federal government’s EnergyMadeEasy website to compare rates on offer in your area, or check out Solar Choice’s Retail Electricity Plan Comparison Tool.

Additionally to ensure you get the most out of solar investment, sourcing a number of competitive solar quotes is important to making a well-informed decision. We have created Australia’s only online quote comparison tool with the objective of helping customers find good quality installers in their area. Enter your postcode below to get started.

Compare quotes from up to 7 pre-vetted installers in your area now.

Since 2008 our knowledge and sophisticated software has allowed over 160,000 Australian households and businesses to make a well-informed choice on their solar & battery installer.

Also, see our new Solar Plus Battery Payback Estimator


  1. What would you expect to be the approximate out of pocket cost to be in Melbourne for a 5.6kw system with Fronius inverter and 470w Jinko panels? That is, taking advantage of the STC and $1400 Vic govt rebate.

    1. Hi Brian,
      Your best options would be to review the average pricing on our Solar Choice Price Index page which is updated each month. Note that these prices exclude the Vic govt rebate however.

      For example we can see that a 5kW system would cost $4,540 in May 2022 in Melbourne or $3,140 after the Vic govt rebate. Looking through our database I can see that there are prices for Fronius / Jinko systems around that price. You can access these quotes and installers through our online solar quote comparison tool.

      Hope that helps,
      Jeff @ Solar Choice

  2. HI, I’ve just completed having a good around and doing the costings on your website. I have two questions:

    1. There are two panel pricings available. It would appear that one is Premium quality and the other is less quality. Is this correct? Do we get a choice?
    2. Most comanies are offering up to 50% Govt subsidy at the moment. Do the prices on your quotes here iniclude that subsidy or is that offered after someone contacts us? eg I have been quoted $6900 for a 6.6KW system with excellent quality panels etc. My cost is half that due to subsidy.

    1. Hi Peter,

      Thanks for your question.

      1. Generally solar installers have different ‘tiers’ of offers depending on customers budgets and preferences. In our system the premium offer is the best quality ‘tier’ the solar installer offers. So it sounds like you are on the right track. Yes you have a choice – if you use our free comparison tool, you can freely browse between the Premium Tier and the Primary Tier.

      2. The prices on the solar choice price index include the Federal Government STC rebate. That normally equates to about 30-35% of the price. There is an additional state rebate in Victoria which is not included in our figures. If your price is $3,450 for a 6.6kW then that would likely be using more cost effective products rather than top quality (without seeing the quote).

      You can review our independent product reviews here, or feel free to email us at (attn Jeff) if you want any more specific advice.

      Jeff @ Solar Choice

  3. I am a sheep farmer and I am considering installing a solar system on a woolshed roof. Our electricity demand on our shed is reasonably low, approx $250/qtr, however at peak management times of the year like shearing time we have a very high and concentrated demand for approx 2-3 weeks where we are drawing high voltage and high amps, could you give some suggestions on how to work out the most efficient system to install on the shed. We would also consume the power in our house which is located approx 200 metres from the shed. I have used the calculator you provide however as I mentioned it is a bit tricky to input our peak amperage draw, thanks and regards George

  4. I currently have a 18 panel 3.2Kw system about 9 years old. I want to enlarge / renew the system, but have no more roof space. How large can I go with new panels?. My current PV was installed through your excellent services almost a decade ago. Note, my solar PV still pumps out heaps even after so many years.

  5. Grab your energy bill and get started..
    I could not Calculate my solar payback period as you do not have Cairns in the list.

    1. That is because Cairns is a hole that nobody cares about. Also, it says to pick your closest city. Brisbane would be the one you should select.

    2. Hi John,

      Unfortunately its tough to cater to everyone in Australia with this public calculator. Selecting Brisbane will be a reasonable estimate – otherwise I suggest you go through our comparison portal and our installer partners will be happy to put together a customer analysis for you.


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