How Many Solar Panels Do I Need?


Deciding how many solar panels will be suitable for your household can be slightly more complicated than choosing a number and going for it. To get the real benefits of a solar power system, a more useful question to ask is, what size solar power system will best to cover your energy usage while having a fast return on investment. Determining this and deciding on what size solar power system is suitable for you will give you an indication on the number of solar panels required.

house solar system sizes

What size solar power system to choose?

Your household’s annual energy usage is going to be the best way to figure out what size solar power system will be fitting to your circumstances and most effective at reducing your electricity bills. Thankfully you can calculate your annual energy usage easily by looking over your electricity bills over the past 12 months and adding up the usage. Once you have done this, you can closely match your energy usage to a solar power system size that has a similar estimated energy production.

To assist you with closely matching your energy usage to a solar power system size, we’ve created a table with some of the most common residential solar power system sizes in Australia. Each system size has an estimated annual production, recommended number of solar panels and your expected savings.

System Size
Number of Panels (approx.)
Production Annually (approx.)
Reduction To Bill Annually (approx.)
2 kW 6-8 3,000 kWh $360-$580
3 kW 10-14 4,900 kWh $480-$800
5 kW 17-20 7,100 kWh $720-$1200
6.6 kW 20-26 10,600 kWh $800-$1600
7 kW 23-28 12,320 kWh $1200-$2020
10 kW 33-36 14,380 kWh $1600-$2800

If your preferred size is not on the above table, you can work out the number of panels recommended by multiplying every 250 W by 4, e.g. 1 kW solar power system would require 4 solar panels.

Solar power system’s return on investment

As a guide to working out your return on investment, you can look at average solar power system prices and divide the cost by the system’s estimated yearly reduction to your bills. In most cases, a residential solar power system will pay for itself within 2-5 years of being installed. As solar power systems have a lifespan up to 25 years, this means any savings made after this term are just additional funds for your savings or holidays!

Roof Space

It’s important to note that the amount of roof space you have might be a restriction on the size solar power system and the number of solar panels you can install. For that reason, it is best practice for a solar installer to do a home visit before providing an accurate quote.

Get in touch with local solar installers and request 3 obligation-free quotes to get closer to reduced electricity bills!

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Download Your FREE Ultimate Guide to Solar Power in Australia - 2021 Edition

Beginners Guide to Solar Power

If you’re considering solar for your property or just looking to maximise the savings for your solar system, download a FREE copy of our "Ultimate Guide to Solar Power in Australia - 2021 Edition".

Become an expert and better understand the ins and outs of solar power and solar PV systems for your property.

Includes detailed explanations and diagrams of the various types of solar systems and their parts, solar battery storage systems, Government incentives, expected ROI periods, finance, energy-saving tips and more!

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Understanding Batteries

Off-Grid Systems

For some households a battery system can be of great benefit and minimise a home’s reliance on the grid. However, it’s important to understand for a battery to be useful your solar system needs to be generating excess energy for the battery to store, which you can then use at night or when the sun is not out.

When selecting a battery, you’ll want to invest in a system that is most suited to your home and can drive the best return on investment (ROI). Despite a larger upfront cost, a higher quality battery may significantly increase your ROI.

    Battery systems start from $6,000 and costs can vary greatly based on the following factors:

  1. Cycle Life-Time

    The number of times a battery can fully charge and discharge.

  2. Battery Power (kW)

    How fast it can be charged or discharged.

  3. Storage Capacity (kWh)

    The maximum amount of energy a battery system can store.

  4. Battery Management System (BMS)

    An electronic ‘smart’ system that gathers data and manages the battery ensuring it does not overload or operate outside of its safe functioning zone..

  5. Inverter

    Battery systems require their own inverter if your solar system does not have a hybrid inverter.

  6. 'All-In-One Unit’

    A system which includes the battery, BMS and an inverter all in one unit.

  7. Warranty

    Length of time or cycles the battery system is under guarantee.

  8. Blackout Protection/Backup

    It’s important to note this is not a common feature of a battery system and could cost thousands of dollars to include. Blackout protection not only requires additional components but also a specialised installation and rewiring. For grid-connected homes, the cost for blackout protection can outweigh the benefit.

Additionally, if your purpose for adding battery is to go Off-Grid and become completely independent from the grid you will need to ensure your solar system can generate enough energy to power your home and your battery system is large enough to store this energy. For homes in metro areas going Off-grid is not cost effective and is only recommended for those in remote areas with limited access to the grid. Off-grid solar systems with battery start at approximately $30,000.

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