If you’re considering adding an Emergency Power Supply (EPS) to your solar panels and battery system, you’re not alone. As more homes across Essex, Kent, Suffolk and the wider South East switch to renewable energy, many homeowners are asking whether EPS is a worthwhile investment for extra energy security.
Below, SolarTherm UK breaks down how EPS works, the different backup levels available, installation requirements and whether it’s genuinely needed for most UK homes.
What is EPS (Emergency Power Supply) for Solar Panels?
EPS is a built-in function found in certain solar battery systems that allows your home to continue running essential devices or circuit during a power cut. Under normal circumstances, all solar PV systems disconnect from the grid during an outage to protect engineers working on the grid.
If your system includes EPS functionality, your solar battery can safely provide limited backup electricity if the grid goes down. This means that during an outage, your battery can keep selected appliances, or even your entire home, powered, depending on your chosen configuration.
How Does EPS Work?
When the grid fails, your system automatically or manually shifts over to battery power. To make this possible, an installer must:
- Fit a dedicated EPS consumer unit
- Install a relay to disconnect your home from the grid
- Wire EPS only sockets or circuits
- Configure your inverter to maintain a minimum battery reserve
Some advanced hybrid inverters will also allow the solar panels to continue generating electricity during an outage, further extending your backup duration.
The Four Levels of EPS Backup
EPS, like all parts of solar, is not a one size fits all solution. SolarTherm UK installs EPS in four levels depending on how much backup power you need:
Level 1 – Single EPS Socket
A simple backup option with one dedicated socket. Ideal for phone charging, lamps and low power devices.
Level 2 – Essential Circuits
A selection of circuits are wired into the EPS consumer unit. Typical circuits include lighting, fridges and freezers and broadband routers.
Level 3 – Whole Home Manual Backup
Your entire property can be switched manually onto backup power. This avoids accidental overloading and encourages sensible energy use during outages.
Level 4 – Full Automatic Whole Home Backup
The most advanced level. Your home automatically switches to battery power within seconds of a power cut. Suitable for homes with large battery capacity, higher energy demands and medical or vulnerable needs.
Is EPS Worth It for Essex, Kent and Suffolk Homes?
For most homes in the South East, EPS is not essential, UK power cuts are infrequent and outages in the South East are among the shortest in the country.
Ofgem data shows:
- The average UK home experiences 0.4 power cuts per year
- Total downtime averages around 38 minutes annually
- Power cut frequency has dropped over 40% since 2011
- Outages usually occur during off peak times
EPS rarely offers a strong cost benefit for the average home. Installation typically adds thousands of pounds to a project and most homeowners simply never use it.
When EPS Is Recommended
SolarTherm UK may recommend EPS if:
- You live in a rural area with frequent outages
- You rely on medical or essential equipment
- You want peace of mind or complete energy independence
Do All Solar Batteries Include EPS?
No, only selected solar battery systems are EPS capable, including:
- Voltsmile W-series and H-series
- SolaX hybrid systems
- Tesla Powerwall
Most standard batteries do not include EPS and even when the hardware supports it, EPS still requires additional electrical work to activate.
EPS Installation: What’s Involved?
Adding EPS to your solar and battery system is complex and must be carried out by qualified installers. The process may include:
- Installing a second consumer unit
- Additional cabling and earthing
- Commissioning and testing the EPS mode
- Configuring your inverter’s backup settings
This additional work is the reason EPS installations carry a noticeably higher cost.
Is EPS Worth the Cost?
For most properties in Essex, Kent, Suffolk and the wider South East, EPS is typically not worth the additional investment. Power cuts are too rare and too short for most households to benefit. If you wish to have EPS installed alongside your solar panel and battery system, we would recommend choosing the lowest level of EPS, a single socket is usually enough to keep your phone charged or a lamp on during the short power outages mostly experienced in the UK.
If you experience recurring outages or rely on essential medical equipment, EPS can be an invaluable upgrade to your solar PV and battery system. If you’re unsure, SolarTherm UK can assess your property, usage patterns, risk level, and battery capacity to recommend the best option for you.
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FAQs
What triggers EPS?
EPS activates when your home loses grid power. Your inverter then switches over to the EPS circuits or socket—either manually or automatically depending on your system.
Does EPS let me use solar power during a blackout?
Some hybrid inverters allow continued solar generation during an outage, but not all. SolarTherm UK will confirm this based on your chosen system.
What is EPS overload?
EPS circuits have a maximum power rating. Overloading occurs when too many devices exceed this limit, causing the inverter to briefly shut down the backup supply.
