Household electricity costs comparison with and without solar and batteries

Published On: March 24th, 2021|10 min read|

We’ve compared the electricity costs in a household in WA without solar, with solar, and with solar and battery storage

We’ve compared the electricity costs in a household in WA without solar, with solar, and with solar and battery storage

Find out if it’s worth considering investing in a rooftop PV system – and battery storage

For the purpose of this comparison, the average family is defined as two adults and two children living in a 3 bedroom, 2 bathroom home in Perth WA.​

In October 2020,  Western Australia introduced the new solar PV feed-in tariff scheme called DEBS. Under the new scheme, which applies to new solar systems (as all existing systems remain on the existing scheme), households receive $0.03 per kWh for electricity exported to the grid from 9 PM to 3 AM and $0.10 per kWh for electricity exported to the grid between 3 PM and 9 PM compared to the $0.071 per kWh that homeowners were receiving for exports at any time under the Renewable Energy Buyback Scheme (REBS). ​

These are some of the lowest feed-in rates in Australia. With these low rates, you may wonder if it is still worth considering investing in a rooftop PV system.​

The short is, yes it still makes a lot of sense to invest in a rooftop solar system. However, investing in solar and battery storage together can maximise your long-term benefits. ​

The following graphs compare the cost of electricity in three different scenarios:

The average family* uses approximately 15kWh per day on weekdays and approximately 20kWh per day on the weekend. Assuming the household buys its electricity from Synergy at a flat rate of $0.288 per kWh, the average family spends $1,726.00 a year on their electricity bill. ​

Assuming an increase in market electricity rates of 2% per annum and constant usage, the household will spend $18,919.00 on electricity over 10 years.​

The average price per kWh over the ten-year period is $0.315.

* For the purpose of this comparison, the average family is defined as two adults and two children living in a 3 bedroom, 2 bathroom home in Perth WA.​

Assuming the installation of a 6kWh rooftop solar system with northward orientated solar panels costs $6,360* and the system produces 10,895kWh of electricity in a year~.

The addition of solar power decreases the household electricity bill in a year by 54% from $1,726.00 to $802.00​ due to electricity costs being offset by both self-generated electricity and the amount of electricity sold back to the grid for the applicable FiT^.

When compared to the home without solar over the same 10 year period, total electricity costs are reduced from $18,919.00 to $9,133.00, and the average cost per kWh reduces from $0.315 to $0.25″.

*Average marketed price​
~With a degradation rate of the output of 0.8% per annum for the following years after installation. ​
^Since most of the export happens before 3pm, the FiT is $0.03 per kWh​
“Taking into account the original investment of $6,360 for the solar system installation​​


The majority of the economic benefit is achieved through the use of self-generated electricity within the home during the day when energy is produced. However, the household still needs to buy a significant amount of electricity from the grid at the energy retail rate of $0.288​. While there is a large quantity of export for the feed-in tariff, there is little economic benefit.

Stacked benefits from installing a PV system:

61% of electricity is still coming from the grid after the installation of a 6.0kW PV system:

The income from export (FiT) only provides 28% of the economic benefit from 72% of the produced electricity:

78% of the self-generated electricity is exported:

Assuming the installation of a Redback Smart Hybrid battery system with 6kW of northward orientated solar panels, and 7kWh of battery capacity has been installed* and all other data remains unchanged.​

The amount of electricity purchased from the grid decreases significantly with the addition of battery storage, reducing the electricity bill to $297.00 per annum compared to $802.00 from solar alone.​

By storing the excess generated energy rather than exporting it, FiT income is reduced to $190.00 in the first year (down from $257.00 with solar only).

However, the household was able to save $572 on its bill by utilising every stored in its battery rather than purchasing it from the grid in the early evenings.

The Redback Smart Hybrid System reduces the total cost of electricity over the same 10 year period to $1,937 (Compared to $18,919 for no solar and $9,133 for rooftop solar only) and the blended average price of electricity per kWh reduces from the original price of $0.315 to $0.23 per kWh​.

*An initial capital investment of $12,000 was assumed after STC deduction​


The total degree of self-sufficiency is about 72%, meaning 72% of the home’s electricity demand is now met by self-generated electricity that is 100% clean. ​In addition to the direct financial benefits of owning a battery storage system, you also receive benefits such as backup power in case of a utility grid outage and opt in schemes such as virtual power plants which can have additional financial incentives.

Impact of adding a Redback system with 7.0kWh of battery capacity:

Electrical budget of a house with PV and 7.0kWh battery:

Share of self-generated electricity per use case:

Economic benefit of self-generated electricity per use case:

Determining what is right for a household depends on the available budget of the household as well as personal preferences with regards to certainty and predictability.​

Location-specific factors can also play an important role in establishing a home’s priorities. For example, value of back-up power can be seen higher in non-metropolitan or rural areas compared to inner-city suburbs. ​

What is clear, however, is that there are significant savings and long-term benefits associated with the installation of rooftop solar and battery storage.​

Battery storage solutions are mature and often affordable. Finding the right-sized option for your home can help you get the best benefits for your money. ​

Quality and performance are just as important as good, local support from a qualified and certified installation partner. ​

At Redback Technologies, we pride ourselves on our quality battery solutions and are more than happy to put you in touch with one of our qualified partners in your area for a free consultation.​

Want to find out if a Redback Smart Hybrid System can help you to be more self-sufficient in your home?

Get in touch with us today and we can connect you to one of our trusted installers in your area.