5kW Solar System In Australia (All You Need To Know)

Australia receives good solar irradiation year-round. Central Australia receives as high as 1,900 kWh/kWp/year compared to Northern Australia at 1,600 kWh/kWp/year and Southern Australia at 1,400 kWh/kWp/year.

What these numbers signify is that if you install 1 kWp of solar panels at the three locations (central, north, and south), you can expect to produce the above-mentioned units of electricity per year.

Below is a solar power potential map of Australia. Please refer to the scale mentioned at the bottom of the figure to determine the annual solar production based on your location.  

Solar power potential map of Australia.

Solar is perhaps the cheapest and the most cost-efficient way to reduce your energy cost.

On average the household electricity tariff for a customer connected to the national grid in Australia is 0.312 AUD/ kWh and for customers living off-grid, it is 0.510 AUD/ kWh (assuming the off-grid customers rely on diesel generators to meet their energy demand).

If you install 1 kWp of solar panels and residing in Sydney, your annual electricity savings will be 436 AUD per year if connected to the national grid and 714 AUD per year if you are living off-grid.  

The annual savings are calculated by multiplying the annual solar production with the electricity tariff.

Solar panels, mounting structures, and cables have a lifespan of over 25 years. In most financial models’ solar panels are written off after 30 years of operations.

However, the balance of systems which includes inverters, batteries, and other electronics have a much shorter life and there might be a need to replace them more than once across the life of the project.

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How Many Solar Panels Do I Need For A 5kw Solar System?

If you are connected to the grid, a typical 5 kWp rooftop solar plant will consist of the following items:

  • Solar panels
  • Mounting structures
  • Cables (DC, AC, Earth)
  • Inverter
  • Protection devices (breakers)

The latest solar panel available in the market are well over 500 Wp. If you can get your hands on a 500 Wp solar panel, for a 5 kWp system you will require 10 solar panels.

You determine the number of solar panels required by dividing the total solar capacity you want to install by the wattage of the solar panel.

In this instance, you divide 5 kWp with 500 Wp to calculate the number of solar panels required.

Regarding the mounting structure, there are different options based on whether it’s a ground-mounted solar system or a rooftop solar system.

If it’s a rooftop solar system, there are different types of mounting structure solutions available. This will depend on the type of roof (sandwich panel, single sheet, concrete, standing seam, etc)

If you are living off-grid, in addition to the above-mentioned items, you will need to consider batteries. There are two types of batteries that are being commercially used, these are lead-acid and lithium-ion.

Lead-acid batteries are bulky, heavy, have a low energy density, a lower depth of discharge, and low cycle life.

Lithium-ion batteries on the other hand are less bulky, comparatively lighter, have a higher energy density, a higher depth of discharge, and a much longer lifespan.

In general, you will notice a transition from lead-acid to lithium-ion batteries among off-grid customers.

Lead-acid batteries have a life between 2 and 3 years, whereas lithium-ion batteries have between 15 and 17 years, assuming 1 cyclic charge and discharge cycle per day.

How Much Does A 5kw Solar System Cost?

When determining the price of a 5kw solar system, you need to consider the cost of the following :

  • Solar Panel
  • Mounting structure
  • Inverter
  • Cabling
  • Installation

The solar panels cost around 3,750 AUD for a 5 kWp system and the inverter is approximately 2,690 AUD.

The cost of the balance of the system which includes the mounting structure, cables, and protection devices should be between 1,000 AUD to 1,500 AUD. This will be based on the roof type and distance from the solar panels to the inverter position.

In total, the material cost for a 5 kWp solar system can be in the range of 7,500 AUD to 8,000 AUD. The installation cost should be between 1,000 AUD to 2,000 AUD. So, in total the installed cost for a 5 kWp solar solution is around 10,000 AUD.

When you are considering an off-grid installation, in addition to the above-mentioned cost, you will need to consider battery cost.

Battery cost is mainly dependent on the type of technology and size of the battery. The correct way to go about sizing the battery is to understand your daily energy demand and peak loads.

In most cases, one can see a 1:2 ratio between solar panels and batteries.

For a 5 kWp solar solution, you will need 10 kWh of battery storage. The additional cost of battery storage is approximately 10,000 AUD.

How Much Money Will A 5kw Solar System Save You Every Year?

When calculating payback, you need to consider the total investment made and annual savings from solar.

The total capital expenditure on a 5 kWp solar plant is 10,000 AUD and the annual savings is 2,184 AUD/ year. A simple payback calculation will show a payback in 4.5 years.

For a 5 kWp solar plant with 10 kWh of lithium-ion battery storage, the total capital expenditure is 20,000 AUD and the annual savings is 3,570 AUD/ year. A simple payback calculation shows that you will achieve payback in 5.6 years.

To compare pricing, for a solar-only solution you can expect an average installed cost of around 2,000 AUD per kW.

For an off-grid system, you can expect an average installed cost of around 4,000 AUD per kW.

As the plant size increases, economies of scale kick in, and the installed price drops. For example, a 1 MWp solar plant installed cost will be around 1,500 AUD per kWp.

Final Thoughts (And Steps To Follow)

In short solar makes technical and commercial sense. The below section details the steps in the process to install solar at your homes.

Step 1

First, you need to understand your daily energy demand and sketch out a load profile. Once you have this, you can understand how much energy you consume per day and what your peak load is.

Step 2

Next, you need to understand how much solar electricity can be generated from 1 kWp of solar installation based on the image shared above. If you are in Southern Australia, your average annual solar production is 1,400 kWh/kWp/year, this is around 3.8 kWh/day.

Step 3

Divide your daily energy demand by your solar production number to determine the total solar capacity required. For example, if your daily energy demand is 20 kWh, you divide 20 kWh by 3.8. The result is 5.26. In short, to meet the energy demand of 20 kWh per day you need to install approx. 5 kWp of solar.

Step 4

Ensure you have sufficient roof area to install solar panels. On average you need 10m2 of roof area to install 1 kWp of solar. To install 5 kWp of solar you will need approx. 50m2 of roof area.  

Step 5

Contact a solar professional to do the procurement and installation works. Or if you are a qualified and trained electrical engineer, you can try and install the solar plant yourself.  

Step 6

Start saving money!

Shanker Mohanan, M.Eng
Shanker Mohanan, M.Eng

Shanker Mohanan has 10+ years of experience in the renewable energy industry and has designed, built, and operated projects in North America, Africa, Middle East, and Asia. Shanker holds a Master`s degree in Power Engineering from the Technical University of Munich, Germany.