Solar panels and battery storage can help reduce your reliance on the electricity grid every day. But what happens when the grid actually goes down?

It's a common assumption that having a battery automatically means your home will continue running during a power cut. In reality, your system needs to be specifically designed and configured to provide backup power safely when the grid fails.

This is where whole home battery backup comes in.

Available across our Solar Essentials, Solar Advantage and Solar Signature systems, whole home backup can take a solar and battery installation beyond everyday energy saving and add another valuable benefit: greater energy resilience when the grid isn't available.

What is whole home battery backup?

Whole home backup allows a suitably designed solar and battery storage system to provide electricity to your property when there is a power cut.

During normal operation, your property remains connected to the electricity grid while your solar panels and home battery help manage your energy requirements.

When a grid outage occurs, the backup system detects the loss of grid power and safely isolates your property from the network before allowing the battery and compatible solar system to supply the home.

When grid power returns, the system can transition the property back to normal grid-connected operation.

Do solar panels work during a power cut?

This surprises many homeowners: simply having solar panels doesn't necessarily mean your home will remain powered during a blackout.

Grid-connected solar systems have to operate safely when the electricity network fails. A suitably configured backup system provides the necessary separation between your home and the grid so that compatible solar and battery equipment can continue operating safely in backup mode.

If protecting your home against power cuts is important to you, backup requirements should therefore be considered while the system is being designed rather than after installation.

What is EPS?

EPS stands for Emergency Power Supply.

Many hybrid solar inverters provide an EPS or backup output that can supply electricity when grid power is unavailable.

A traditional EPS arrangement will often be configured around selected essential circuits or loads rather than automatically supplying every circuit in the property.

For example, a homeowner might prioritise items such as:

• Refrigeration and freezers.
• Lighting.
• Internet equipment.
• Selected sockets.
• Heating controls or other essential equipment, where appropriately designed.

The precise loads that can be supported depend on the inverter, battery, electrical installation and system design.

What is the difference between EPS and whole home backup?

The biggest practical difference is what part of your house the backup system is designed to supply.

An EPS installation can be configured to provide backup to selected circuits. Whole home backup is designed so that the property as a whole can remain connected to the backup supply, subject to the output and stored energy available from the solar and battery system.

Does whole home backup mean unlimited power?

No, and this is probably the most important thing to understand about whole home backup.

Whole home backup means the system can be designed to supply the property during an outage. It doesn't turn the battery into an unlimited source of electricity.

How much you can run, and for how long, will depend on factors including:

• Battery capacity.
• Battery state of charge when the outage begins.
• Available inverter backup output.
• The number and type of appliances being used.
• Available solar generation during the outage.
• The configuration of your particular system.

High-demand appliances can consume stored energy much faster than lighting, refrigeration or internet equipment.

Good backup design is therefore about balancing power and stored energy, not simply adding a backup box.

What are the benefits of adding whole home backup?

For many homeowners, battery storage starts as a way to reduce electricity costs. Adding backup creates a second purpose for that investment.

Potential benefits include:

• Keeping your home powered during grid outages.
• Automatically responding when grid power fails.
• Making your battery useful for energy resilience as well as everyday savings.
• Supporting home working and internet connectivity during an outage.
• Helping keep important household equipment operating.
• Making solar, battery storage and backup part of one integrated home energy system.

The value of backup will differ between households, but for customers who increasingly rely on electricity for working, heating, communications and transport, energy resilience can be an important consideration.

Solar Essentials: Fox ESS whole home backup

Our Solar Essentials package uses the Fox ESS H1-G2 hybrid inverter and compatible Fox battery storage.

The H1-G2 provides EPS capability, while Fox offers the EPS-BOX-SP specifically for single-phase whole-home backup.

The EPS-BOX-SP sits between the Fox inverter, utility supply and household circuits. If grid power fails, it isolates the property from the grid and switches to the inverter's backup supply.

Key features include:

• Automatic grid-to-backup switching.
• Whole-home backup capability, subject to system sizing and load requirements.
• Typical transfer time of approximately 2–3 seconds.
• Up to 100A utility input and output current.
• Integration with compatible Fox ESS single-phase storage systems.

The Fox solution gives Solar Essentials customers a practical route from standard EPS functionality to an automatically switched whole-home backup installation.

Solar Advantage: EcoFlow OCEAN 2 whole home backup

Solar Advantage is designed around the EcoFlow OCEAN 2 modular solar and battery platform, alongside EcoFlow's intelligent home energy management technology.

Key Features Include:

• Integrated whole-home backup.
• 0ms load-side switchover under supported grid conditions.
• 100A whole-home backup.
• Integration of solar generation, battery storage, backup and energy use within the EcoFlow ecosystem.

This makes EcoFlow particularly interesting for homeowners who want backup to sit alongside advanced monitoring and home energy management rather than operate as a separate feature.

As with any system, the precise backup capability depends on the specific OCEAN 2 model and configuration selected for the property.

Solar Signature: Sigenergy SigenStor whole home backup

Our premium Solar Signature package uses Sigenergy SigenStor, a modular home energy platform combining solar, battery storage and energy management.

When paired with the appropriate Sigen Energy Gateway HomePro, SigenStor can provide whole-home backup functionality.

The HomePro SP-F is designed for whole-home backup on a single-phase supply and provides:

• 100A single-phase whole-home backup capability.
• 0ms load-side disruption when transitioning to backup.
• 100A grid and backup circuits.
• Integrated monitoring and energy management through the mySigenergy app.
• Support for smart load management.
• Support for compatible generator integration.

Sigenergy's smart-load functionality can also be used as part of backup management, allowing compatible loads to be managed in relation to battery state of charge.

That makes SigenStor particularly suited to our Solar Signature proposition, where the emphasis is on maximum performance and a more comprehensive home energy solution.

How much battery storage do I need for whole home backup?

There isn't one battery size that is right for every home.

A larger battery can hold more energy, but battery capacity is only one part of backup design. The inverter also needs sufficient output to support the loads you want to operate.

For example, a household that primarily wants to maintain refrigeration, lighting and internet connectivity has very different backup requirements from one expecting to operate multiple higher-powered appliances simultaneously.

That's why we recommend designing your battery storage system around both your everyday electricity consumption and your priorities during a grid outage.

Can solar panels recharge the battery during a blackout?

With a suitably designed and configured system, compatible solar generation can contribute to supplying the home and battery while the property is operating in backup mode.

This can be particularly valuable during a longer outage because the amount of stored electricity available when the power cut begins isn't necessarily the only energy resource available to the system.

How much solar energy is available will naturally depend on the time of day, season, weather and solar array.

Is whole home backup worth adding?

If power cuts are rare where you live, whole home backup may not be the first feature you consider when investing in solar and battery storage.

But the way homes use electricity is changing.

Home working, connected technology and increasing electrification mean many households are more dependent on a reliable electricity supply than they once were.

Whole home backup turns battery storage from purely an energy-saving asset into part of your home's energy resilience strategy.

For some homeowners, selected-circuit EPS will be sufficient. For others, the simplicity and coverage of whole-home backup will justify designing it into the system from the outset.

Which whole home backup system is right for me?

The best solution depends on more than the backup gateway itself.

The solar panels, inverter, battery capacity, backup output, household loads and energy management system all need to work together.

That's why Renewable Energy Service offers three distinct home solar packages:

• Solar Essentials – a reliable solar and battery system using trusted components, with Fox ESS whole-home backup available.
• Solar Advantage – enhanced performance, monitoring and greater self-sufficiency using EcoFlow OCEAN 2, with whole-home backup available on supported configurations.
• Solar Signature – our premium home energy solution for maximum performance, using SigenStor with whole-home backup available through the appropriate Sigen Energy Gateway.

Rather than asking which backup box is best, we think the better question is: what do you want your home to keep doing when the grid goes down?

Once we understand that, we can design the solar, battery and backup system around your priorities.