Do Solar Panels Work During a Power Cut?

The Complete Guide to EPS and Home Backup

One of the most common questions we hear at SolarTherm UK is:

“If there’s a power cut, will my solar panels keep my house running?”

The answer surprises many homeowners.

In most cases, no. Even if the sun is shining brightly, standard grid connected solar panels automatically switch off during a power outage. The good news is that with the right battery storage system and backup configuration, your home can continue running during a blackout.

This guide explains everything you need to know about Emergency Power Supply (EPS), whole home backup and which battery systems can keep your lights on when the grid goes down.

Why Do Solar Panels Switch Off During a Power Cut?

Most residential solar PV systems in the UK are connected to the National Grid. When the grid loses power, your inverter automatically shuts down. This is called anti-islanding protection.

It isn’t a fault with your system – it’s a legal safety requirement designed to protect engineers working on damaged power lines. Without this protection, your solar panels could continue exporting electricity into the grid, creating a serious safety risk. So even if your roof is generating electricity, your home will normally lose power unless your system has dedicated backup functionality.

Can Solar Panels Work During a Power Cut?

Yes – but only if your system ahs the correct equipment. To continue using electricity during a blackout you’ll normally need:

• Solar panels
• Battery storage
• A compatible hybrid inverter
• Backup functionality such as an Emergency Power Supply (EPS) or whole home backup system (sometimes known as a Gateway)

Without these components your solar panels will shut down until grid power returns.

What Is EPS (Emergency Power Supply)?

An Emergency Power Supply (EPS) allows your battery system to safely supply electricity when the grid fails. Instead of feeding electricity into the National Grid, the system isolates your property and creates its own safe electrical supply.

Depending on the system you choose, this can power:

• A dedicated backup socket
• Essential household circuits
• Most of your home
• Your entire property automatically

How Does EPS Work?

When a power cut occurs, the backup system disconnects your home from the National Grid. Your battery then supplies electricity directly to your home. Many modern hybrid systems can also continue using electricity generated by your solar panels during daylight hours, helping recharge the battery and extend backup time. The exact behaviour depends on the inverter, battery systems and backup hardware installed.

Different Levels of Backup Power

Every household has different requirements. At SolarTherm UK we can configure several levels of backup depending on your needs.

Level 1 – Backup Socket

The simplest and most affordable option. A dedicated socket continues working during a power cut and can be used for phone charging, laptops, lighting, broadband router or medical equipment.

Level 2 – Essential Circuits

Selected circuits remain powered. Typically these will be lighting, fridge, freezer, Wi-Fi, boiler controls or a home office. This provides a good balance between cost and functionality.

Level 3 – Manual Whole Home Backup

Your entire property can be supplied by the battery, but you manually activate backup mode. This allows you to prioritise which appliances are used and helps prevent overloading the system.

Level 4 – Automatic Whole Home Backup

This is the highest level of protection. If the grid fails, your home automatically switches onto battery power within seconds. In many cases you may barely even notice the outage. This option is particularly popular with homeowners who work from home, have medical equipment, experience frequent power cuts or who want to maximise energy independence.

Which Battery Systems Support Backup?

SolarTherm UK supplies several battery systems capable of providing back up power.

• Hanchu ESS: Hanchu battery systems provide backup power to the level you require. Install an optional Gateway for full home backup.
• Tesla Powerwall 3: the Powerwall 3 includes integrated backup functionality, allowing seamless whole home backup.
• Sigenergy SigenStor: the SigenStor offers one of the most advances backup solutions available and can provide whole home backup when installed with the optional Gateway.

Can My Solar Panels Recharge My Battery During a Blackout?

Often, yes. Many modern hybrid battery systems continue using solar generation during daylight hours while operating in backup mode. This means your battery can recharge from your solar panels while the grid is unavailable, helping extend the amount of time your home can remain powered. The exact functionality depends on the equipment installed, so it’s important that your system is designed correctly from the outset.

How Long Will My Battery Last During a Power Cut?

There isn’t a single answer. Backup duration depends on:

• Battery capacity
• Household electricity usage
• Which appliances are running
• Solar generation during the outage

For example, running lighting, Wi-Fi and a fridge requires far less energy than operating an electric shower, oven or EV charger. Using only essential appliances can significantly extend the amount of time your battery provides power.

Is Backup Power Worth It?

For many households, standard solar panels and battery storage already provide excellent savings without backup functionality. However, adding EPS or whole home backup can provide valuable peace of mind. Backup can provide valuable peace of mind.

Backup power may be particularly worthwhile if you:

• Live in a rural area where outages are more common
• Work from home
• Have vulnerable family members
• Rely on medical equipment
• Simply want greater resilience

For others, a simple backup socket or essential circuits may provide all the protection they need. At SolarTherm UK we’ll discuss your requirements and recommend the most suitable level of backup for your property rather than a one size fits all solution.

What Does Installing EPS Involve?

Installing backup functionality requires additional electrical work beyond a standard solar installation. Depending on the level of backup selected, this may include:

• Additional consumer units
• Automatic transfer equipment or Gateway devices
• Backup circuit wiring
• Electrical isolation equipment
• System commissioning and testing

As every property is different, the exact installation requirements vary.

Choosing the Right Backup Solution

When designing a solar and battery system it’s important to think beyond today’s electricity bills.

Ask yourself:

• Do I want my home to stay powered during outages?
• Which appliances are essential?
• Would I prefer automatic or manual backup?
• Do I want whole home protection or just essential circuits?

Planning for backup during the initial installation is often the simplest and most cost effective approach.

Why Choose SolarTherm UK?

With over 16 years experience installing solar PV and battery storage across Essex, Kent, Suffolk, Hertfordshire and the wider South East and East Anglia, SolarTherm UK designs every system around the customer’s lifestyle and energy usage.

Whether you’re looking for a straightforward battery installation or a fully integrated whole home backup solution, our experienced team can recommend the right equipment to match your needs.

Contact SolarTherm UK today for a free, no obligation quote and design, tailored to your property, usage and future energy needs. No hard sell, just honest, expert advice – and the time you need to make an informed decision.

Your home. Your energy. Your future.

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