Question: Is Installing a solar battery in South Australia really worth it?

Answer:  It’s Complicated

There are many people that buy solar batteries for different reasons, other than pure financial returns. Although we are going to look at the question in a purely financial sense.

The financial answer to this really comes down to what type of energy user you are and how much of that energy use can be replaced by solar and a solar battery. It comes down to 4 major factors.

When do you use electricity? (i.e. time of day/ week)

How much solar energy will you generate from your roof?

How much energy do you use?

What is the maximum amount of solar electricity you can sell to the grid? 

When do you use electricity?

A working household may use energy mainly in the morning or night 5 days per week, and a bit more on weekends during the day.

A retail shop, may operate 9-5 Monday to Friday and be closed on weekends. So most electricity is consumed during opening hours and can be easier to work out when your electricity is used.

Many households aren’t aware of exactly when they use electricity, and this can be a major factor in any solar PV or solar battery purchase decision. 

Traditionally, electricity retailers have only provided average energy use per day or month on your bills. Fortunately, there are now smart meters being rolled out across the state and some really advanced apps are available to break down household energy consumption. 

So as the very first step, householders should go to their energy retailers website and download their app. If you are not happy with their app, look at new retailers like Amber Electric. 

Once you find out exactly how much and when you use electricity, you can really dig down into the potential financial benefits of solar and solar batteries.

For the sake of our analysis, we are going to give some ‘averages’ for South Australia.

30kWh of electricity consumed per day. 

60% of Electricity consumed during daylight ‘solar hours’ 

40% of electricity consumed at night ‘battery hours’ 

Solar Generation and battery usage. 

If you already have solar, then it’s likely that you have already experienced some of the benefits of solar. You currently use some of your solar energy in your home, and some of it is ‘sold’ to your electricity retailer as a feed-in tariff. 

There is a commonly held misbelief that all of your solar energy is sold and you receive a feed-in tariff for all of it. In South Australia, this is not true. 

We have what is known as a net feed-in tariff.  Solar energy produced on your roof is used in your home or business first, and only the surplus is sold to the grid.

The financial value of a solar battery is derived from the solar electricity that you produce, from your roof, which is surplus to your needs, at the time it is being generated.

In the past, South Australian consumers have been chasing electricity retailers for the highest ‘feed-in tariff’ and have typically paid a premium on the electricity that they buy. 

With a solar battery, consumers look for the cheapest per kWh rate on the electricity that they buy from their electricity retailer and don’t worry about the feed-in tariff. 

We have been very excited about a new electricity retailer called Amber Electric. Amber offers a unique deal where you have access to wholesale rates for electricity and allows you to sell any excess solar electricity also at wholesale rates. 

Example;  

Home using 30kWh of electricity per day

6kW solar PV array 

13kWh battery. 

Solar Production. 

A 6kW Solar Power system will produce 25.2kWh of electricity per day. – More about how to calculate solar production. 

Electricity Usage. 

The ‘average home’ uses 30kWh per day of electricity. 

Time of day

60% used during daylight solar hours (15.12kWh)

40% used at night 10.08kWh

The financial model with a battery and solar.

Solar generates 25.2kWh

You use 15.12kWh

With a battery

You store 10.08kWh

You buy 4.8kWh

The financial model with just solar. 

Solar generates 25.2kWh

You use 15.12kWh

Without a battery

You sell 10.08kWh

You buy 14.8kWh

The financial model with no solar or battery.

You buy 25.2kWh

Input Costs.

• Electricity standard rate $0.36 per kWh
• Market-leading feed-in tariff $0.18 per kWh

Average installed price for; 

• 6kW Solar (After STC rebate) $4,500
• Tesla Power Wall 2 (after SA Gov rebate) $10,000

Financial analysis

With battery and solar 

Solar benefit $5.44 per day

Battery benefit $3.62 per day

Electricity bought from grid $1.72 per day

With just solar 

Solar Benefit $5.44 per day

Feed-In Benefit $1.81 per day

Electricity bought from grid $5.32 per day

No solar or battery

Electricity bought from grid $10.80 per day

Annual electricity bills 

• No solar or battery $3,942
• With just solar $1,281
• With solar and battery $627

Return on investment

Already have solar just buying a battery 

Investment $10,000

The additional benefit from battery $654 per year. 

ROI 15.29 years.

Buying solar and a battery 

Investment $14,500

Benefit from solar and battery $3,315 per year

ROI 4.37 years.

Buying Just solar

Investment $4,500

Benefit from solar $2,661 per year

ROI1.69 years.

In summary, 

It’s really worth understanding your exact energy usage and the times that times energy is used. As this can change the above figures drastically. 

The price you pay for electricity is a major factor in how these examples work. 

If you are not buying solar at all or are buying solar and a battery, we recommend you check out Amber Electric to access wholesale electricity prices.

The other factor to consider is how much electricity you are allowed to sell to the grid. In South Australia, a single-phase home can export up to 5kW per hour, so if you have a roof that can fit more than a 5-6kW system, then the financial case for a battery maybe even better. 

See some of our packages below. 

Our popular solar and battery packages.