How Big a Battery Do I Need to Take Advantage of Free Daytime Electricity?

Free electricity in the middle of the day changes the way we need to think about home energy.

From 1 July 2026, eligible NSW households can access the Australian Government’s Solar Sharer Offer, providing up to 24 kWh of free electricity between 11 am and 2 pm each day. That creates an interesting opportunity for households with a home battery, solar panels or an electric vehicle.

Instead of simply asking: “How big should my solar battery be?” there is now a much better question: “How much energy can I shift into the free electricity period and use later when power becomes expensive?” The answer isn’t necessarily to install the biggest battery possible.

The smartest approach is to look at your whole energy system: Solar. Battery. EV. Electricity plan. Because increasingly, the best-performing home energy system is the one where everything is designed to work together.

The Solar Sharer Offer is an optional electricity plan introduced in July 2026. For eligible NSW households, it provides:

• free electricity between 11 am and 2 pm
• up to 24 kWh of free electricity each day
• access for both homeowners and renters
• no requirement to already have rooftop solar
• eligibility subject to having a compatible smart meter and meeting the retailer requirements.

Importantly, the electricity outside the free period is not free. Daily supply charges and electricity rates outside 11 am-2 pm still apply.

That is why homeowners shouldn’t choose an electricity plan based solely on the words “three hours free”. The real question is how much of your electricity consumption you can shift into those hours and what your electricity costs during the remaining 21 hours of the day.

There isn’t one correct battery size for every home. The right solar battery size depends primarily on:

• how much electricity your household uses after 2 pm
• your overnight electricity consumption
• whether you already have solar panels
• the size of your solar system
• whether you own an EV
• when your EV is normally at home
• whether your battery can charge from the grid
• your electricity tariff outside the free period
• your battery’s usable storage capacity
• whether you want blackout protection
• whether you plan to electrify more of your home in future.

The Australian Government notes that typical household batteries have traditionally ranged from around 4 kWh to 14 kWh, although larger and modular systems are increasingly available. For homes taking advantage of free daytime electricity, however, your evening and overnight consumption becomes particularly important.

An example

Imagine your household typically uses:

• 4 kWh between 2 pm and 5 pm
• 8 kWh during the evening
• 3 kWh overnight.

That’s approximately 15 kWh of electricity after the free-power window ends. If your battery could be charged during the day,  using a combination of solar and eligible free grid electricity,  a battery with sufficient usable capacity could potentially carry much of that energy into the evening.

But if your household only uses 6–8 kWh overnight, installing a 30 kWh battery simply because you can access 24 kWh of free electricity may not deliver the best return. Battery size should be based on the energy you can actually use, not simply the amount you can charge for free.

Learn more about solar battery storage 

Potentially, but not automatically. Traditionally, a solar battery is primarily charged using surplus rooftop solar generation. Free daytime electricity creates another possible energy source.

A compatible battery may be able to charge during the 11 am–2 pm free electricity window and then supply your home later when electricity rates are higher. That can make additional storage capacity more useful for some households. However, there are several questions to consider before increasing your battery size.

How much electricity do you actually use after 2 pm?

If your battery regularly finishes the night with significant stored energy remaining, additional capacity may achieve very little.

How quickly can your battery charge?

A 20 kWh battery doesn’t necessarily mean it can absorb 20 kWh within three hours. Battery charging power, inverter capacity and system configuration all matter.

How much solar are you already producing?

If your rooftop solar is already filling your battery by midday, free grid electricity may add relatively little benefit.

Do you have an EV?

An electric vehicle can absorb considerably more electricity than most household batteries, making EV charging another valuable use for the free-power period. Learn more EV charger installation

What does electricity cost outside the free period? This is crucial. A free electricity window isn’t automatically a cheap electricity plan. You need to compare the daily supply charge, peak rates, shoulder rates and off-peak electricity prices as well.

Yes, potentially, provided your battery system and electricity arrangement allow grid charging. Many modern home batteries and energy management systems can be configured to charge from the grid according to a time-of-use schedule. For example, a compatible system could potentially be programmed to:

11 am: start grid charging
2 pm: stop grid charging
Afternoon/evening: discharge stored electricity into the home.

However, not every battery, inverter or configuration supports the same level of control. Grid charging can depend on:

• battery brand
• inverter
• installation configuration
• software settings
• retailer conditions
• Virtual Power Plant participation
• energy management controls.

If your battery is connected to a Virtual Power Plant (VPP), there may also be specific rules about when the provider can charge or discharge your battery. The NSW Government currently offers incentives for eligible batteries connected to participating VPPs, so homeowners should consider battery control and electricity-plan compatibility together.

It depends on what paid electricity each free kilowatt-hour would otherwise replace. This is where home energy management becomes particularly interesting. Imagine you have three hours of free electricity and both your battery and EV need charging. You could:

Charge your EV directly

If the car is parked at home between 11 am and 2 pm, charging it directly during the free period can be highly efficient. There is little reason to charge a home battery first and then transfer that electricity into an EV later if the vehicle can simply take the electricity directly during the free window.

Charge your home battery

Charging the household battery can also make sense if that energy will later replace expensive evening electricity. For example, using free electricity at midday and storing it to avoid peak-rate electricity at 6 pm may potentially save more than using that same electricity to replace an already-low overnight EV charging tariff.

Charge both intelligently

For households with solar, battery storage and an EV, the best answer may be dynamic control. Your energy system could prioritise:

1. household electricity consumption
2. available rooftop solar
3. battery charging
4. EV charging
5. grid electricity during the free-power window

depending on your electricity plan and household requirements. There is no universal rule that says “battery first” or “EV first”. The priority should be based on which strategy produces the greatest overall saving.

A larger battery may be worthwhile, but free electricity alone isn’t a reason to oversize your battery. The Solar Sharer Offer currently provides up to 24 kWh of free electricity per day during the NSW 11 am–2 pm period. That does not mean every household suddenly needs a 24 kWh battery. Consider a household that only consumes 10 kWh after 2 pm.

If it charges a 24 kWh battery every day but regularly has substantial energy left the following morning, a significant portion of that storage capacity isn’t delivering additional savings. On the other hand, a larger battery may become more attractive for homes with:

• high evening electricity consumption
• ducted air conditioning
• electric hot water
• pool equipment
• induction cooking
• multiple occupants
• an EV
• future electrification plans
• higher peak electricity prices
• significant backup-power requirements.

Think about battery utilisation, not battery capacity alone.

Yes. Your access to the Solar Sharer Offer’s free electricity period isn’t dependent on the sun shining on your particular house. The offer was introduced because Australia’s electricity grid often has abundant solar generation during the middle of the day.

So even if it is cloudy or raining at your Sydney home, eligible electricity consumed during the free-power period can still qualify under your plan. This can actually make battery storage interesting on poor solar-generation days.

On a sunny day: Solar → home + battery

On a rainy day: Free grid electricity → home + battery

Later: Battery → evening household consumption

A well-designed energy system can potentially use whichever source makes the most sense at that particular time.

For many Sydney homes, yes. Three hours of free electricity does not replace rooftop solar. There are still 21 other hours in the day. Solar can generate electricity throughout the daylight period, not just between 11 am and 2 pm. Your solar system may be able to:

• power your home throughout the day
• charge your battery
• charge your EV
• reduce grid electricity consumption
• export surplus electricity
• reduce exposure to future electricity-price changes.

A free electricity plan should therefore be considered another tool in your energy strategy rather than a replacement for solar. The best financial outcome depends on your individual consumption profile, solar production, battery size and tariff.

Many modern battery systems can be programmed to charge at specific times, but it depends on the battery and inverter configuration. Some systems allow homeowners to create time-of-use schedules that automatically respond to different electricity tariffs.

For example:

6 am-11 am Use solar and normal household electricity.

11 am-2 pm Prioritise free electricity, battery charging, EV charging and other flexible household loads.

2 pm–5 pm Use solar generation and stored battery energy where appropriate.

Evening peak – Use stored battery electricity to reduce expensive grid imports.

Overnight – Maintain battery reserves or access cheaper off-peak electricity according to your energy plan.

Advanced home energy management can increasingly coordinate these decisions automatically. That is why choosing a battery is no longer only about brand and kWh capacity. The battery’s controls, inverter, solar system, EV charger and electricity tariff can all affect how effectively the system performs.

If you’re on a suitable free-electricity plan, the battery and EV aren’t your only opportunities. You may also be able to schedule high-energy appliances between 11 am and 2 pm, including:

• dishwasher
• washing machine
• clothes dryer
• pool pump
• electric hot water
• air conditioning
• heat-pump systems
• EV charging
• home battery charging.

Instead of thinking only about producing more electricity, homeowners increasingly need to think about when they consume it. This is known as load shifting. And in the new electricity market, load shifting may become just as important as solar generation.

The way Australians use electricity is changing. For years, the basic solar strategy was simple: Generate electricity during the day and reduce how much electricity you buy from the grid. Then home batteries arrived. Then EV charging. Then time-of-use tariffs.

Now we have electricity plans offering periods of free power. That means every part of the home energy system can affect everything else.

Your solar system isn’t working alone anymore. Solar. Battery. EV. Electricity plan.

The smartest system is the one designed to work together.

Before choosing a bigger battery, adding more solar panels or installing an EV charger, MPV Solar can review your actual electricity consumption and help determine how each part of your system should work together.

Rather than simply asking:“What size battery can I fit?” we’d rather answer: “What combination will deliver the best result for your home?”