Is it Worth Installing a Battery With Your Solar System?

The quick answer is yes, but the solar battery needs to be bundled with a good-quality solar system. In general, it is always better to install a battery with your solar system, as this can reduce the overall cost and can improve the purchasing discount.

If you buy a solar panel battery and solar combination system together with a new house or undertake a major renovation, then the system cost can be integrated with your mortgage. In this case, the Return on Investment (ROI) will become excellent due to the current low-interest rates.

It can even get better with government subsidies, incentives, vouchers, and rebates.

Solar systems in the Cairns region with solar battery storage can achieve an ROI of between 4 to 7 years, depending on the brand of panels, inverter solution etc as well as consumption patterns and installation difficulties.

What is the best location for my residential solar battery?

The best location is determined by new Australian Standards AS/NZS 5139: 2019 Electrical installations and AS 5409.16 (maintenance). The Clean Energy Council has a summary of the standard on their website, so follow the link above.

Nowadays you cannot install solar batteries in liveable areas, and they need to have a 600 mm clearance on either side and be located 900 mm above the ground.

They also require having fire-resistant material behind the product (This can easily be achieved by installing fibro or cement sheeting). There is also no room for any flammable materials near the battery and it’s important to have some ventilation.

So, when you decide to have a battery storage system, given the above considerations, where is the best space in your home for such an installation?

Usually, we at Replenishable Energy find a great spot is in the garage, or if you built a new home, why not design a dedicated area for your energy equipment inside the house.

Other good locations are outdoors on a wall that is protected from direct sunlight or a spot where a protective shade structure can be installed easily.

What size solar battery will I need?

Ask yourself, how many people are in my household, and what is our average daily electricity consumption? If you use for example 40kWh of electricity a day, a 5 kWh solar battery system size will not be enough.

Your household is more likely to benefit from a solar battery storage system if you use a higher than average amount of electricity which would be more than 6,000 kilowatt-hours a year.

Naturally, a storage unit can help when you use a large part of your electricity in the evenings or at night. In such cases for example a 13.5kWh Tesla Powerwall or even 2 Tesla units could be the right size to serve your needs.

Another consideration for the size of the storage device is to understand the usable part of the total capacity. The usable part is called nominal capacity.

A 10 kWh unit for example from a particular manufacturer might only make 85% of that kWh available to run your essential services. So instead of getting 10 kWh, you can only harvest 8.5 kWh before the system controller shuts off.

Naturally, with any large battery, you also need the matching PV system, to maximise the total amount of renewable energy being generated and preserved

This is to protect the battery, as the more and deeper the product gets discharged, the shorter the life span. So, make sure you ask for the nominal capacity of your unit, not just the nameplate capacity.

Why is solar battery storage a clever idea?

If you have a pool and need to run the pump in the evenings or at night, a solar panel battery can help.

Another good reason is if you have or plan to get an electric vehicle that you can charge at night from the battery storage unit and re-charge it during the day.

If you live in an area with numerous blackouts and you need a backup for your essentials, such as fridge lighting, TV, internet then a solar power battery can be a lifesaver.

If your feed-in tariff is very low – then storing the electricity instead can be a good option to achieve a better financial return on your solar system.

Also, if you are in an area with fire risk where you need to have the electricity working so your firefighting water pump will work to douse your property, an electricity storage device can make all the difference.

Then there is the lifestyle choice be certain you can enjoy energy independence. Why send your electricity back into the grid and receive only a few cents, when one can store it in the battery on-site, and get the full value, by using it later at night.

How much does a solar battery cost?

To start with a battery and solar bundle one has to allow for a minimum of $15,000 in their budget and depending on the size of the battery and solar system, bigger amounts will be required.

The payback depends on your individual consumption pattern and ranges between 4 to 8 years.

This is where finance can help to make a battery purchase more affordable. By using monthly repayments one can get into a position where the electricity savings are relatively close to the monthly instalment costs.

Therefore, over the years your payments, instead of paying the energy retailer, with no long-term benefits, will contribute to your ownership of a quality solar and battery system. Talk to our battery experts on how we can help you finance a home battery purchase. 

The payback of a quality solar panel system only without the batteries will be shorter than a bundled solution. Nevertheless, a standard solar system will shut off during a blackout, giving you no benefit, compared to households that have no solar, while a battery will keep the lights on.

LG Energy Solar Battery Solutions Cairns Replenishable Energy

We offer many brands, like this LG Energy Solutions product (formerly known as LG Chem)

Not all home solar battery brands and inverters are capable

Make sure you check that the recommended product offers black-out protection. We have seen in the Cairns region several times homeowners buying a battery, only to find out at the next blackout, that the battery inverter is not equipped with a backup module.

If you face a blackout, make sure you conserve your energy consumption to some degree so that your solar during the day can charge the battery for use at night.

A blackout is not the time to start baking cakes and bread in the electric stove, as you will exhaust your battery and then have no power as well.

By being conservative in the electricity consumption, with a large enough solar system and battery, theoretically, you could stay in power for weeks, without the grid being restored.

If your house is power-hungry it might pay to only have a few of the most vital circuits connected to your battery. In this case, the essentials like the fridge, some lights and charging your modem, your washing machine and TV will always stray connected.

Most importantly you need to watch out that the size of your solar system and the size of your battery is matched. In Cairns for example an 8kw solar system will generate a total output of 13,905 kWh per annum.

In regard to the average output per month the data is as follows:

July: 965 kWh

August:  1104 kWh

September:  1286 kWh

October: 1352 kWh

November:  1382 kWh

December: 1375 kWh

January: 1263 kWh

February: 1128 kWh

March: 1124 kWh

April: 1052 kWh

May:  982 kWh

June: 893 kWh

The average kWh generation per day during the year for this 8kw PV system is 38.10 kWh.

Let’s assume the particular homes average daily consumption is 22 kWh.

The spare generation of around 16kWh daily can go into the battery. Therefore, a 13kWh size Tesla could be the right size. But if the house has a larger consumption during the day, then there would not be enough spare export to fill the 13kWh unit, and maybe a slightly bigger PV system would be needed.

Monitoring your consumption and feed-in

How much involvement do you want to have with making sure your solar and battery system works well? A good monitoring and battery control system is a must, and Replenishable Energy can recommend the best solutions.

Most inverter manufacturers such as Fronius, SMA, and Sungrow as well as battery manufacturers such as LG Energy Solutions, Tesla, BYD and Sungrow have their own internet portal as part of the setup.

This data will show how much you have produced over a certain time. These monitor solutions also show when you have fed in power to the grid, how much you have taken from the grid, how much CO2 generation you have avoided etc.

The minimum monitoring system you should consider is one that shows how much electricity your solar system produces.

It should also show how much is consumed by the house at any given time. How much is diverted to storage, or if at night, how much the battery is delivering to the house? It should also clearly indicate what capacity is remaining in storage.

Replenishable Energy also provides a service, where we can remotely check for any problems that may occur and either repair them remotely or follow up via our friendly and reliable after-sales service.

The lifespan of different types of batteries

  • Lithium Iron Phosphate is 7 to 12 years
  • Lithium Cobalt Oxide 5 to 7 years
  • Lithium Manganese Oxide 10 to 30 years
  • Lead Acid 3 to 15 years

Lithium batteries such as Tesla and LG Energy Solutions (previously LG chem) have greater storage and release power than lead-acid batteries of a similar size and weight. They charge faster than lead-acid batteries, flow batteries, and saltwater batteries, and represent modern battery technology.

Replenishable over the past 3-4 years has installed over 50 battery setups in the wider Cairns region and can provide free advice on the best solution for you.

QLD Solar Rebates, incentives, subsidies

There are different rebates available when purchasing solar or a solar and battery combination and depending on the size of your system, these Government rebates can represent many thousands of dollars. These rebates and incentives change from time to time, so call us on (07) 4031 2251 / 1300 682 773 to get the latest up-to-date QLD solar rebate and battery info.

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