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 $0.71 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:

1 – A household
without solar

2 – A household with solar but no battery storage

3 – A household with solar and battery storage

Navigate through the slides below to read the comparison and view the graphs.

No solar power * 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.​ Scenario 1 - household electricity consumption in kWh over 24 hour period (average, weekdays) Scenario 1 - Cost of electricity without solar power 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 With solar power *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​​ Scenario 2 - with changed power flows from adding a 6.0kW PV system Scenario 2 - Cost of electricity with solar power 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****​ With solar CHARTS Scenario 2 - stacked benefits from installing a PV system Cost of electricity with solar power - CHARTS 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 ​ 61% of electricity is still coming from the grid after 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 With solar and battery *An initial capital investment of $12,000 was assumed after STC deduction​ Scenario 3 - Cost of electricity with solar power and battery storage 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 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) but the household received $572.00 in savings due to increased self-consumption.​

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​
Scenario 3 - Impact of adding a Redback system with 7.0kWh of battery capacity With solar and battery CHARTS Cost of electricity with solar power and battery storage - CHARTS Scenario 3 - Impact of adding a Redback system with 7.0kWh of battery capacity Electrical budget of a house with PV and 7.0kWh battery Economic benefit of self-generated electricity per use case Share of self-generated electricity per use case 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. Final Thoughts​ Final Thoughts​ 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 in 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.​