Simple Solar Calculator

This very easy to use simple solar calculator will show you your approximate first year savings from your solar power system based on: 

  • how much sun you get
  • how many solar panels you buy 
  • how much energy your home uses in daylight hours
  • how much you pay for grid electricity
  • what feed in tariff your electricity retailer pays you

Step 2 of my book, the Good Solar Guide, details how to calculate how much energy your home uses in daylight hours.

Step 4 of the book shows you how to decide how many panels to buy - and it explains why a 6.6kW solar system is the best choice for many people with a single phase electricity supply.

Your electricity usage rates and feed in tariff depends on your electricity retailer. Don't forget that most Australians have a wide choice of electricity retailers - and they all have different rates. You can see your local retailer options here.

Simple Solar Savings Calculator


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The number produced by the calculator gives you a good idea of the value of solar power for your home.

If you divide the number by 4, you’ll get a feel for how much your quarterly electricity bill will reduce.

If you divide the approximate cost of your system by your first year’s savings, you get the ‘simple’ payback: how long it will take until the system has paid for itself. From that point, it should sit there providing free electricity for decades, aside from perhaps an inverter replacement somewhere along the way.

How this simple solar calculator works:

1. Calculate system output for your chosen system size

First, we need to estimate the average daily energy output (in kWhs) of your system. 

This is the number for the area you live in multiplied by the system size:

Table 1. Average daily output by city

Average daily output per kW installed  (kWh/kW per day)
Adelaide 4.2 
Alice Springs 5.0
Brisbane 4.2
Cairns 4.2
Canberra 4.3
Darwin 4.4
Hobart     3.5
Melbourne 3.6
Perth 4.4
Sydney 3.9

Find the city nearest to you and multiply your system size by the number.

For example, if you’ve chosen 3 kW of panels and you live in South Australia, your average daily output is: 3 kW x 4.2 = 12.6 kWh per day.

Write your daily output here:

System’s energy output 
= ___ kW of panels x ___ kWh/kW per day (from Table 1) 
= ___ kWh per day.

2. Calculate daily savings from self-consumption

Your savings from solar electricity self-consumption are your daytime usage multiplied by your usage tariff.

Note: If your daytime usage is more than your system output, the solar power system you have selected is way too small. If you can’t get a bigger system then your daily savings are limited by your output. Multiply your usage tariff by the system output instead.

Write your daily savings from self-consumption here:

Dollar savings from self-consumption
= daily usage (____ kWh per day) x usage rate ( ____ c per kWh)
= ____ c per day.

3. Calculate how much energy you’ll export

The amount of energy you export is your system output minus your daytime electricity usage:

Write the amount of energy you’ll export here: 

Exported kWh
= System output (_____ kWh per day) - daytime consumption (_____kWh per day) = _____ kWh per day.

4. Calculate your daily earnings from exports

Your earnings from exports are your exported kWh multiplied by your feed-in tariff tariff.

Note: If your daytime usage is more than your system output, you have no export earnings.

Write your earnings from exports here:

Dollar earnings from exports
= exported kWh (_____ kWh per day) x feed-in tariff (____ c per kWh)
= _____c per day.

5. Calculate your total daily savings

Your total daily savings are your self-consumption savings added to your export savings.

Write your total daily savings here: 

Total daily savings
= self-consumption savings ($ ______) + export earnings ($_______)
= $_______ per day.

6. Calculate your first year’s savings

Your first year’s savings are your total daily savings multiplied by 365 days.

Write your first year’s savings here:

Your first year’s savings
= daily savings $______ x 365
= $______ per year.

I hope you found this simple solar calculator useful! By the way, if you haven't checked out my book, learn more about The Good Solar Guide: 7 Steps To Tiny Bills For Australian Homeowners! In the market to buy a system? Get up to 3 solar quotes via my free service from trusted, pre-vetted installers matched to your requirements.