You’ve covered the roof in solar panels. On a sunny day, they’re pumping out plenty of power. So why are you still getting an electricity bill?
For a lot of solar homes, there’s a mismatch between when that power is generated and when it’s needed. Your panels are busiest during the day, but your household might use more power in the morning and evening. Any solar you don’t use as it’s generated heads out to the grid, and once the sun goes down, you’re back to buying electricity from the grid.
A battery lets you hang onto some of that excess solar and use it later. But to understand what difference that can make, it helps to look at what’s happening to your solar without one.
Why can your electricity bill still be high with solar?
Solar can reduce how much electricity you need to buy from the grid, particularly when you can use the energy your panels generate as it’s produced.
The tricky part is that household energy use and solar generation don’t always line up.
Your panels generate while the sun is shining, with output typically strongest around the middle of the day. But your home may need more electricity later, as you cook dinner, run appliances, heat or cool the house and generally get on with the evening.
If your panels are producing more electricity than your home needs at the time, that excess solar is exported to the grid. Once solar generation drops away, you’ll need to import electricity again if your home still needs power.
So you can end up exporting excess solar during the day, then paying to import electricity later.
What happens to the solar power you don't use?
Without a battery, excess solar generation is generally exported to the grid.
On a traditional electricity plan, you’ll usually receive a feed-in tariff for those exports. The amount you receive depends on your electricity plan.
The value of electricity itself, however, changes throughout the day.
Australia now has so much rooftop solar that periods of strong solar generation can push daytime wholesale electricity prices very low, and sometimes negative. At other times, when electricity is in higher demand or there is less supply available, wholesale prices can rise.
A traditional feed-in tariff generally doesn’t expose you to those movements in the wholesale price. Depending on the plan, you may receive the same rate for your exports regardless of what electricity is worth on the wholesale market at that moment.
For a solar household without storage, there’s also a physical limitation: you can use your solar when it’s being generated or export the excess. You can’t save it for later.
That’s what a battery changes.
What does adding a battery to solar actually do?
A home battery lets you store some of the solar energy your panels generate during the day and use it later.
Instead of immediately exporting all your excess solar, you can charge your battery. Then, when your solar generation falls in the evening, your home can draw energy from the battery rather than relying as heavily on the grid.
That gives you more control over when your solar energy is used.
It also means the value of your solar is no longer tied quite so closely to the exact moment your panels generate it. Energy generated in the middle of the day can be stored and used hours later.
But adding a battery introduces another question: what should the battery do with the energy it’s storing?
How does an electricity plan affect what your battery can do?
A battery gives your home flexibility. How you use that flexibility depends partly on the electricity plan sitting behind it.
Many batteries can be set up to prioritise self-consumption. They store excess solar during the day and discharge later when your home needs electricity.
With access to wholesale electricity prices, a battery can also respond to changes in the value of electricity.
Wholesale prices change throughout the day as supply and demand across the grid change. There can be periods when electricity is very cheap or negatively priced, as well as periods when prices rise sharply.
That creates more choices for a battery. Depending on the conditions, it may make sense to store solar, charge from the grid, hold energy for later, use stored energy in the home or export it.
Working out the best option requires knowing what’s happening with your home and the energy market, and continuing to adjust as those conditions change.
How does Amber work with solar and batteries?
Amber gives customers direct access to wholesale electricity prices.
For compatible home batteries, SmartShift automatically manages when the battery charges and discharges. It forecasts your household electricity usage, solar generation and wholesale electricity prices, then uses that information to plan how your battery should operate. That plan is continually updated as conditions change.
So on a sunny day when there’s plenty of cheap energy available, SmartShift can take that into account when deciding when to charge your battery. When wholesale prices rise, it can decide whether stored energy is better used in your home or exported to the grid.
During rare wholesale price spikes, export prices can reach as high as $19 per kilowatt hour, or $21 per kilowatt hour in South Australia. SmartShift is designed to respond automatically, rather than requiring you to watch electricity prices and decide what your battery should do yourself.
The aim is to make better use of the flexibility you already have in your battery, based on what your home and the grid are doing.
Do you need a battery if you already have solar?
A battery isn’t automatically the right choice for every solar household.
But if you regularly generate more solar than you can use during the day, adding storage gives you another option for that excess energy. Instead of having to use it immediately or export it, you can store some of it for later.
That can be particularly useful for households whose electricity use is higher outside solar generation hours.
If you’re looking at adding a battery, it’s worth thinking beyond the hardware itself. The electricity plan and software controlling the battery affect how it can use, store and export energy once it’s installed.
Solar gives your home a way to generate its own electricity. A battery gives you more control over when you use it. And smart automation can help decide what to do with that flexibility as conditions change.
Already have solar? See how a battery and Amber could help you make more of the energy you generate.
