How To Store Solar Energy At Home

Many Australians are embracing renewable energy and tapping into the power of solar technology to generate electricity to run everything in their home or business, from lightbulbs to air conditioners. In this article, we explore everything you need to know about how to store solar energy at home, storing solar energy in batteries, the cost of a solar battery storage system, and how to choose the right battery for your needs.

Storing Solar Energy in Batteries

First, let’s start with the question, ‘How do solar batteries work’? Solar batteries give you the ability to harness solar energy at all hours. Instead of generating solar energy during the daytime, sending any excess solar power back to the electricity grid to receive a low feed-in tariff and purchasing electricity off the grid at night, solar batteries store the energy produced by your solar panels for later use. Whenever your solar panels are producing more electricity than you need, this excess energy will charge and fill your solar battery. Later, when your solar panels aren’t producing electricity, you can draw upon the solar energy you stored earlier. It’s super simple. 

There are many advantages to storing solar energy in batteries. With solar battery storage, your property has the potential to become its own electricity self-sufficient island that is less dependent on power from the grid. You’ll only send electricity back to the grid when your battery is fully charged, and you’ll only draw electricity from the grid when your battery is depleted. 

Without a home battery, your excess solar energy is often sold to the power company. Many Australian families don’t realise that when they need that power in the evening, they are purchasing that same power back from the grid at a higher price than they sold it. Another added bonus solar batteries also provide backup power to protect your home in the case of a blackout. 

How To Compare Your Solar Battery Storage Options

Here are the most important product specifications to consider when you are comparing and contrasting different solar battery storage options. 

Capacity and power rating

Capacity (measured in kilowatt-hours or kWh) is the total amount of electricity a solar battery can store. The higher your battery’s capacity, the more solar energy it can store. Most residential solar batteries in Australia are ‘stackable’. This means you can ‘stack’ multiple batteries to achieve a higher storage capacity. 

Power rating (measured in kilowatts) is the amount of electricity that your battery can deliver at one time. 

To forecast a solar power battery’s effectiveness with accuracy, it’s important to consider both its capacity and its power rating. 

A battery with high capacity and a low power rating could deliver a low amount of electricity for a long time ⁠— enough to power a few appliances. A battery with low capacity and a high power-rating could run your entire home, but only for a few hours. 

Solar battery lifespan: How long will my battery last?

How long your solar battery lasts ultimately depends on the brand of battery you buy and how much capacity it will lose over time. 

For example, a battery may have a warranty of 5,000 cycles or 10 years at 70 percent of its original capacity. At the end of the warranty, the battery will have lost no more than 30 percent of its original capacity to store energy. 

Depth of discharge vs cycle life

Let’s talk about depth of discharge and cycle life. 

To keep a solar battery working efficiently, it must retain a certain amount of charge at all times. The amount of a battery’s capacity that has been used is called its depth of discharge (DoD). 

Using all of a battery’s charge at once will significantly decrease its cycle life. 

A higher depth of discharge typically means you’ll be able to use more of your battery’s capacity. 

If a solar battery has a 10 kWh capacity with an 80 percent depth of discharge, plan to recharge before the battery uses more than 8 kWh. 

All batteries degrade in performance and their ability to sustain charge the more you use them. As a result, most manufacturers will provide a warranty that guarantees that their solar battery will last a certain number of cycles or years of useful life. 

Round trip efficiency calculation

A solar battery’s round-trip efficiency describes the kWh of energy received from the electricity divided by the kWh of energy fed into the battery. For example, 4 kWh of useful electricity received back / 5 kWh of electricity fed into the battery = an 80 percent round-trip efficiency. A higher round-trip efficiency means your battery will be more cost-effective. 

Solar Storage Batteries

Here’s a description of the current solar battery types available in Australia:

Lead-acid solar batteries

  • Ideal for off-grid energy systems
  • Least expensive
  • 1000-3000 cycles
  • 60% depth of discharge
  • A lifespan of 2-8 years

Lithium-ion solar batteries

  • Most popular home energy storage technology in Australia
  • 4,000 – 6,000 cycles
  • 80-90% depth of discharge
  • A lifespan of 13-18 years

Flow solar batteries

  • 4000 cycles
  • 100% depth of discharge
  • Can tolerate extreme weather conditions, up to 50 degrees Celsius

Solar Battery Storage System Cost

Solar battery storage typically starts at $5,000 for a smaller solar battery storage system — the equivalent of $105 per month for five years. In contrast, larger batteries like the Tesla Powerwall 2 will cost between $12,500 and $14,000. 

Are solar panels, combined with solar battery storage, the future of energy in the home? Investing in solar energy is a great way for Australian families to help reduce the world’s reliance on fossil fuels. For all your solar energy needs, get in touch with Peak Voltage on (07) 3272 7325.