Solar Battery Storage – Everything to Know

Solar Battery Storage – Everything to Know

Last updated on October 10, 2023

Solar battery storage refers to batteries that can store excess electricity generated during the day by rooftop solar systems.

The stored solar energy in the batteries can be used at night or during blackouts and power outages. So, solar battery storage provides homeowners with energy independence and security.

The most common types of batteries used for home solar storage are lithium-ion batteries – the same battery technology used in laptops, phones, and electric vehicles.

Popular solar battery options in Australia include Tesla Powerwall, Alpha ESS, LG Chem, and Sonnen. A typical solar battery for a household system has a usable capacity of 5-15 kilowatt-hours.

How Does Solar Battery Storage Work?

A solar storage battery is connected to the home’s rooftop solar PV system, by either AC or DC coupling. During the day, when the solar system generates more power than needed, the excess solar electricity is stored in the battery.

Then, in the evening, when solar generation is reduced, stored energy can be drawn from the battery to power home appliances, lights, etc.

Solar homes with battery storage rely much less on the electricity grid by using more of their own stored solar power. Batteries also provide backup power during blackouts.

Smart software manages the solar battery system, optimizing solar self-consumption and grid interaction.

What Are the Benefits of Adding Battery Storage?

There are several benefits that battery storage offers for homes and businesses whether they have existing solar panels or are planning to install a new solar and storage system:

  • Increase solar self-consumption – With batteries, much more solar energy is used directly in the home rather than exported. This provides greater energy independence.
  • Avoid peak demand charges – Using solar energy stored in batteries reduces peak usage from the grid when electricity rates are highest. This can help you save on your power bills.
  • Backup power during blackouts – Battery systems provide emergency backup to keep essential lights, appliances, and devices powered during grid outages.
  • Increase energy independence & bill savings – Solar batteries allow greater energy independence where you can use the stored power in your batteries, reducing reliance on the grid and energy bills.

Are Solar Batteries Worth the Investment?

The biggest question among many Australian households and businesses is whether adding a solar storage battery is worth the cost.

Solar battery storage does involve a significant upfront investment, where an average lithium-ion battery system installation costs between $8,000 to $15,000.

However, batteries can provide excellent return on investment over their lifespan by increasing solar self-consumption and avoiding peak grid power rates.

Solar batteries make the most economic sense for properties with high daytime usage.

The payback period depends on factors like your existing solar system size, electricity tariffs, power usage patterns, and battery size.

Generally, it’s estimated solar batteries can provide a payback over 5–10 years for typical households. Payback would be faster at under 5 years for larger battery systems above 10 kWh.

Battery costs are also expected to continue falling, improving the cost-benefit equation.

So, solar storage is becoming a smart investment for many Australian households, especially as blackouts become more frequent.

What Size Solar Battery Do I Need?

Choosing the right battery size is important to maximize the benefits.

Your ideal solar battery capacity depends on factors like your existing solar system size, energy usage patterns, tariff rates, and budget. As an approximate guide:

  • 5 kWh battery: suitable for 1-2 kW solar systems, provides partial backup for essentials.
  • 10 kWh battery: Suitable for 4-6 kW solar, provides full overnight power backup.
  • 15 kWh+ battery: This provides multi-day power backup for larger 6 kW+ solar systems.

Many providers offer software tools to help you select the optimal battery size for your home’s needs and budget.

It’s best to undersize slightly rather than oversize your solar battery. Oversized batteries cost more but provide less economic benefit.

Installing Solar Battery Storage

Adding a solar storage battery to an existing solar PV system is just matter of a straightforward battery retrofit.

A lithium battery is installed alongside or under the solar inverter and connected via AC or DC coupling.

AC coupling is simpler as it doesn’t require any changes to the PV array. Your solar installer will fully configure and integrate the system.

New solar and storage systems are also easy to install, with the battery component integrated.

Make sure to choose a reputable solar installer who is experienced with storage installations and can advise on optimal sizing for your home. Ask for multiple quotes comparing quality battery brands like Tesla, Sonnen, LG, and Alpha ESS.

The Outlook for Solar Batteries

As solar power has gone mainstream in Australia, solar battery uptake is rapidly increasing.

Market analysts forecast that by 2030 over 2 million Australian homes could have solar battery storage installed. This distributed battery storage is helping stabilize grids and reduce reliance on gas peaker plants.

Key factors driving strong growth in home batteries include:

  • Rising electricity prices
  • Concerns over blackouts as old coal plants are shut down
  • Incentives for adding storage and improving battery economics

As costs continue to fall, payback periods will become even more attractive. So, for many Australians, solar battery storage is now a wise investment to maximize their solar energy usage, lower their bills, and provide greater energy reliability.

Types of Solar Batteries

There are a few main types of batteries used in residential solar storage systems:

Lithium-ion batteries: The dominant choice, lithium-ion batteries provide high efficiency, lifespan, and safety. Major brands like Tesla Powerwall use lithium-ion.

Lead-acid batteries: A cheaper but less durable option than lithium-ion, can have faster discharge rates. It’s only suited to smaller solar systems.

Saltwater batteries: Newer technology using saltwater electrolytes, non-flammable and sustainable but lower energy density.

Flow batteries: Two liquid electrolytes store energy on a larger scale suitable for businesses. It has higher upfront cost but longer lifespan than other types.

In short, Lithium-ion is generally the best technology for home installations when selecting a solar battery, thanks to its balance of performance, lifespan and safety.

Common Solar Battery Brands

A wide range of battery brands and models are available from manufacturers worldwide. Some of the most popular solar batteries found in Australian homes include:

  • Tesla Powerwall – Sleek modular lithium battery designed by Tesla Motors. It’s high quality and comes with a warranty.
  • sonnenBatterie – German lithium battery with eco and smart options. It has proven high performance.
  • Alpha ESS – Budget lithium battery suited to smaller solar systems. It’s good value overall.
  • LG Chem RESU is a reliable lithium battery from electronics giant LG with a slim modular design.
  • Fronius Solar Battery – Designed specifically for Fronius hybrid inverters. It uses Lithium-ion technology.
  • Ampetus Super Lithium – Australia assembled lithium battery range, very customizable sizing.

When comparing different solar battery products, look at specs like depth of discharge, roundtrip efficiency, cycle warranty, size, and price.

It is also important to choose an experienced installer familiar with installing your preferred battery brand.

Adding Storage to Existing Solar

For homeowners who already have solar PV installed, adding a solar storage battery can further maximize your system’s benefits.

Storage retrofits overcome the common issue of wasting excess daytime solar generation.

Installing batteries with an existing solar system is straightforward. Your installer will mount the battery unit on a wall or ground stand and then connect it to the solar inverter via AC or DC coupling.

AC coupling is simpler as it doesn’t require reconfiguring the solar array.

Your new battery capacity should match your average daily solar generation. For example, a 5kW solar system would suit a 10kWh battery.

Your installer can best advise on the right sizing and integration of the new system. Enjoy using more of your solar energy by adding a solar storage battery to your system!

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E-Green Electrical

E-Green Electrical is a top tier energy efficiency company based in Sydney. We focus on utilising government rebates to help reduce our clients energy consumption by installing energy efficient solutions. E-Green boasts a rich heritage within the realm of energy efficiency, consistently staying up to date with cutting-edge technologies to deliver optimal results for our valued customers.

We don't just sell products and services; we also provides tips and information on how to help reduce energy consumption. We believe in using energy wisely and teaching others how to do the same. For E-Green, it’s important to share knowledge with the community. That's why we regularly write articles about saving energy, new government rebates available and increasing sustainability.

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