Last Updated on May 20, 2025

Do Solar Batteries Work During A Power Outage?

As the UK continues to transition toward renewable energy, solar battery storage is becoming an increasingly attractive option for homeowners, landlords, and commercial property owners. But there’s a critical question on many minds: Do solar batteries work during a power outage?

The answer isn’t as straightforward as a simple yes or no, it depends on how your system is set up, the type of battery you have, and whether or not your system is designed to operate off-grid in the event of a blackout.

In this guide, we’ll break it all down for you. If you’re considering solar battery storage for your property, this post will give you clarity so you can make the most informed decision possible.

Do Solar Batteries Work During a Power Cut?

Yes, but only if your system is designed to support it.

In the UK, most solar panel systems are connected to the National Grid. By default, they will shut down during a power outage to protect utility workers from electrical backfeed. This means that a solar panel system without a compatible solar battery and backup gateway will not power your home during a blackout.

However, if your system includes a solar battery storage unit with backup capability (often paired with an automatic transfer switch or an inverter with “islanding” functionality), it can keep essential circuits running.

Key Setup Requirements for Solar Backup During Outages

To ensure your solar batteries will work during a power cut, your system must include:

• Hybrid or off-grid inverter: Standard inverters won’t work without grid power. You need a hybrid inverter capable of disconnecting from the grid and switching to battery power seamlessly.
  
• Backup gateway or EPS (Emergency Power Supply): This ensures that during a grid outage, your battery can safely isolate and continue supplying electricity.
  
• Adequate battery capacity: Your solar battery must be sized correctly to cover your energy needs during a blackout. 

What Can You Power During a Blackout?

A solar battery won’t power your entire home unless you’ve invested in a large-scale system. Instead, most homeowners in the UK opt for essential load backups, covering:

• Fridges and freezers
  
• Wi-Fi routers and modems
  
• Lighting circuits
  
• Sockets for phone charging or medical equipment
  
• Gas boilers (for igniters and smart heating systems)

If you’re wondering how much energy storage you’ll need, check out our guide on what size solar battery I need.

Grid-Tied vs Off-Grid Battery Systems

There are two main types of solar battery systems to consider:

1. Grid-Tied with Backup

This is the most common setup in the UK. Your battery stores excess solar energy and can power essential appliances during an outage.

Pros:

• Grid access for additional electricity needs
  
• Can export surplus energy back to the grid
  
• Typically lower installation cost
  

Cons:

• Limited backup power capacity
  
• Won’t run high-consumption appliances for long durations
  

2. Off-Grid Systems

These are fully independent from the National Grid and require much larger solar arrays and battery banks.

Pros:

• Full energy independence
  
• Resilience during extended outages
  

Cons:

• High upfront cost
  
• Requires expert planning
  
• Often overkill for average UK homes

Choosing the Right Battery for Power Outage Protection

Here’s what to consider when evaluating solar batteries for blackout protection:

Battery Type

• Lithium-ion batteries (e.g., Tesla Powerwall, GivEnergy, SolarEdge) are efficient, compact, and long-lasting.
  
• Lead-acid batteries are more affordable but bulkier and less efficient.

Battery Capacity

Measured in kWh, this determines how much electricity the battery can store. For blackout protection, aim for at least 5–10kWh.

Cost Considerations

The average cost for a solar battery with backup capability in the UK ranges from £4,000 to £10,000, depending on capacity and system design.

Will a Solar Battery Automatically Kick In During a Blackout?

If your system includes an automatic transfer switch or a smart hybrid inverter, then yes—your battery will automatically take over within seconds of a grid outage.

This seamless transition ensures you won’t even notice the switch, especially if your backup loads are well-prioritised.

Solar Batteries vs Backup Generators in the UK

While traditional diesel generators have been used for backup power, solar batteries are:

• Quieter
  
• Cleaner (zero emissions)
  
• More economical in the long run
  
• Eligible for VAT relief and potential grants

Important Compatibility Questions to Ask

Before investing, make sure your installer covers the following:

• Does your inverter support islanding?
  
• Is a backup gateway included?
  
• Can your battery power be isolated from the grid?
  
• What appliances do you want to keep running during an outage?
  
• How long do you want backup power to last?

Can Solar Panels Charge My Battery During a Blackout?

Yes, if you have an off-grid or hybrid system with the right equipment.

Your solar panels will continue to generate electricity during the day, which can recharge your solar battery, but only if the system can safely isolate from the grid.

Request Your Free Solar Battery Quote Today

Ready to make your home or commercial building blackout-resilient?

At Eco Happy, we specialise in designing solar battery systems that protect against power cuts, lower your energy bills, and reduce your carbon footprint, all tailored to UK conditions and local grid requirements.

Free personalised quote
Expert system design
Flexible financing options
Installed by certified UK engineers

Request your free solar battery quote now and find out how much you could save with Eco Happy solar battery storage!