Called back within a day and gave good advice.
Rob and Sue Dempster · Jun 2026 Google
System upgrade · Backup power
EPS installation — backup power from your solar battery
EPS (Emergency Power Supply) lets your battery keep your home running during a grid outage — automatically, silently, and without fuel. From a single backup socket to full-house automatic changeover, there are four ways to configure EPS depending on how much coverage you need.
from £495 · cost confirmed in writing before work
- Switches over in <20ms
- Dedicated circuit from £995
- Most hybrid inverters supported
EPS not working during a power cut?
If your inverter is EPS-capable but your circuits go dark in an outage, the problem is usually a missing neutral-earth bond or the EPS circuit not being correctly wired. We diagnose and fix EPS configuration issues as part of our fault diagnosis service.
Book EPS diagnosis / installationRemote EPS fault diagnosisContacted Solar Tech Support when trying to understand what my Givenergy inverter problem might be and what might be my options. Received good/honest advise which backed up my thoughts.
Hugh Speirs · Apr 2026
Our 3 year old GivEnergy batteries froze. They were showing 0% on the app, but they were fully charged. Some how Ron took over our inverter and remotely cured the problem. We live in King’s Lynn, he is in Leeds I believe. Very grateful.
David Lewin · Jul 2026 Google
Amazing support, went out of his way to help try and get us back up and running
Paul Smith · May 2026
I can’t praise this firm enough. After hearing my solar panels rattling in very windy conditions, I contacted Solar Tech (as my installers no longer trade). Ronald was fantastic at explaining what he thought the issue was likely to be. Communication was great throughout keeping me fully updated. The team worked really hard on the day to carry out the necessary work. I can now sleep soundly at night without worrying about the solar panels on my roof. I would thoroughly recommend this firm. Thank you for sorting the problem out.
Carolyn Addison · Jun 2026 Google
Ron is incredibly knowledgeable about solar installs in general but knows givenergy products inside out and the key personnel that worked there from the start to the end. My problem was spurious in its nature but Ron spotted it straight away when he understood the installation details. In essence the installers didn’t fit the correct trip switch. He also gave me hope that in the future hardware repairs could be possible but it’s still early days. This guy really is in the know and keen to sucas a business If you need help don’t hesitate
Geoffrey Heathcote · Jun 2026 Google
What is EPS and how does it work?
EPS is a feature built into most modern hybrid solar inverters. When the grid supply fails, the inverter automatically disconnects from the grid and switches its output to protected circuits — powered entirely by your battery. This happens in under 20 milliseconds, fast enough that computers and clocks typically keep running without rebooting.
How much of your home gets protected depends on which EPS configuration you choose. A simple wall socket keeps one or two appliances alive. A full-house automatic changeover switch protects every circuit in the building — seamlessly and without any manual intervention.
What EPS does
✓ Keeps selected (or all) circuits running during a grid outage
✓ Switches over automatically — no action needed
✓ Charges from solar during daytime outages
✓ Silent, no emissions, no fuel required
✓ Automatically reconnects when the grid returns
What EPS cannot do
✗ Work without a charged battery
✗ Sustain high-draw loads indefinitely (showers, cookers, heat pumps)
✗ Operate on a string inverter (hybrid required)
✗ Work correctly without proper wiring and neutral-earth bond
✗ Replace a generator for multi-day outages with small batteries
Important: Enabling EPS mode in your inverter portal alone is not sufficient. You must have physical EPS wiring — whether that is a dedicated socket, a sub-board, or a changeover switch. Without the electrical work, enabling EPS mode has no practical effect and the inverter will still shut down your circuits when the grid fails.
Four types of EPS configuration
EPS is not one-size-fits-all. There are four distinct ways to wire EPS backup power, each offering a different level of coverage, complexity, and cost. The right choice depends on how many circuits you want to protect and whether you need automatic or manual switchover.
Type 1
EPS wall socket
£495
A single 13A socket wired directly from the inverter's EPS output terminals. During a power cut, this socket stays live while the rest of the house goes dark. You plug in whatever you need most — a phone charger, broadband router, or extension lead to a fridge-freezer.
Grid outage — EPS socket active
✓ Simplest and cheapest installation
✓ No sub-board or changeover switch needed
→ Only one or two appliances at a time
→ No lighting circuits protected
Typical use: Keep the broadband router and a phone charger running during short outages. Suited to households that rarely experience power cuts but want basic resilience.
Type 2 · Most popular
Dedicated EPS circuit
From £995
A separate EPS consumer unit (sub-board) wired from the inverter's EPS output terminals. Selected circuits are moved onto this sub-board — typically lighting, essential sockets, boiler, freezer, and broadband router. During a power cut, only these protected circuits stay live. The rest of the house remains off until the grid returns.
Grid outage — protected circuits active
✓ Multiple circuits protected (lights, sockets, boiler, freezer)
✓ Automatic switchover — no manual action needed
✓ Best balance of coverage, cost, and battery life
→ Requires rewiring selected circuits to the EPS sub-board
Typical use: The standard recommendation for most homes. Protects 3–8 essential circuits. Battery lasts longer because high-draw circuits (cooker, shower) stay off.
Type 3
Full-house manual changeover
£1,295
A manual changeover switch (typically a rotary isolator) is installed between the grid supply and your main consumer unit. When the power goes out, you physically turn the switch to transfer the entire consumer unit from grid supply to inverter EPS output. Every circuit in the house is then powered by the battery. When the grid returns, you switch it back.
Grid outage — manual switch engaged — whole house on battery
✓ Every circuit in the house protected
✓ No need to choose which circuits to move
✓ Simpler wiring than a dedicated sub-board
→ Requires manual intervention to switch over
→ Everything stays off until you turn the switch
→ Battery drains faster with full house load — manage usage carefully
Typical use: Households that want full-house coverage without the cost of automatic changeover. You need to be home (or have someone home) to operate the switch when the grid fails.
Type 4 · Premium
Full-house automatic changeover
From £1,495
An automatic changeover switch (ATS) monitors the grid supply continuously. The moment the grid fails, the ATS transfers the entire consumer unit to inverter EPS output — automatically and without any manual intervention. When the grid returns, it switches back. The whole house stays powered throughout, with a brief interruption of under 20 milliseconds during switchover.
Grid outage — auto changeover — whole house on battery
✓ Every circuit in the house protected automatically
✓ No manual action — works even when you are away
✓ Seamless transition — most devices do not notice
→ Highest cost option
→ Battery drains faster with full house load — manage usage carefully
→ Larger battery bank recommended (10 kWh+)
Typical use: Households that want complete seamless protection. Ideal when people are often away, when there are vulnerable occupants, or where any interruption to power is unacceptable (medical equipment, home office, security systems).
Quick comparison
| Feature | Wall socket | Dedicated circuit | Manual changeover | Auto changeover |
|---|---|---|---|---|
| Circuits protected | 1 socket | 3–8 selected | All | All |
| Automatic switchover | Yes | Yes | No (manual) | Yes |
| Battery efficiency | Best | Good | Load dependent | Load dependent |
| Works when away | Yes | Yes | No | Yes |
| Starting price | £495 | £995 | £1,295 | £1,495 |
Which inverters support EPS?
EPS capability is standard on hybrid inverters but absent from string inverters. All four configuration types above require a hybrid inverter with EPS output terminals.
EPS-capable inverters (most common)
GivEnergy: AIO 2.0, AIO 2.6, AIO 5.0, All-in-One Gen2
Sunsynk: Sunsynk Hybrid 3.6, 5.5, 8.0 kW
Growatt: SPH 3000–6000TL3, SPA series
SolaX: X1 Hybrid G4, X3 Hybrid G4
Fox ESS: H1, H3, AIO series
Lux Power: SNA / LXP hybrid series
Sigenergy: SigenStor series
Alpha ESS: SMILE5, STORION series
No native EPS — string inverters
SMA Sunny Boy: (standard, non-Storage series)
Fronius Symo: (non-hybrid series)
SolarEdge: (single-phase without backup interface)
Solis string: (non-hybrid models)
Huawei SUN2000: (without backup LUNA unit)
Most pre-2018 string inverters
Not sure about your model? Check your inverter's user manual or search the manufacturer's portal settings. If there is no EPS, backup, or island mode setting, your inverter does not support EPS. The alternative is inverter replacement with an EPS-capable hybrid model.
Why the neutral-earth bond matters
The neutral-earth bond is the single most common reason EPS fails during an actual power cut — and it applies to all four configuration types. Understanding why it is needed prevents the most frequent EPS installation fault.
When the grid is live, your home's earth reference comes from the electricity network. When the grid drops and EPS activates, the inverter output becomes an isolated island supply — the earth reference from the grid disappears. Without a replacement earth reference, RCDs on the EPS circuits cannot function and will trip immediately.
The fix is a neutral-earth bond — a simple connection at the EPS sub-board or changeover point that establishes a local earth reference. This allows RCDs to operate correctly during island mode. Every EPS installation we carry out includes this bond as standard.
If your EPS was installed by someone else and trips during outages: The neutral-earth bond is the first thing to check. It is a quick fix for a qualified electrician and resolves the problem in the majority of cases. See our GivEnergy EPS not working guide for brand-specific troubleshooting.
What EPS installation involves
Regardless of which configuration you choose, the installation follows the same fundamental steps. The complexity and duration increase with more comprehensive configurations.
1
Confirm inverter EPS capability and battery reserve
Before any work begins, we confirm the inverter model supports EPS and that your battery has sufficient usable capacity (minimum 5 kWh recommended for dedicated circuits, 10 kWh+ recommended for full-house changeover). A battery reserve of 20–30% is configured to ensure capacity is always available for EPS use.
2
Choose the right EPS configuration
We assess your property, existing consumer unit layout, inverter location, and which circuits you want protected to recommend the most appropriate of the four configuration types. For most homes, a dedicated EPS circuit (Type 2) gives the best balance of coverage and battery life. If you want full-house protection, we discuss the trade-offs of manual vs. automatic changeover.
3
Install the EPS wiring and switchgear
A Part P certified electrician carries out the physical installation. For a dedicated circuit, this means a new EPS sub-board with selected circuits transferred. For a changeover switch, the switch is installed between the meter and the main consumer unit. All configurations include the critical neutral-earth bond. Work is typically completed in half a day for dedicated circuits, or a full day for changeover switch installations.
4
Enable EPS mode in inverter settings
We log in to your inverter's monitoring portal and enable EPS mode. The exact menu path varies by brand: on GivEnergy it is System Mode Settings → EPS Enable; on Sunsynk it is under Advanced Settings → Off-Grid/EPS; on Growatt, look in System Parameters → Off-grid Settings; on SolaX, it is under Settings → EPS Mode. We also configure the minimum battery reserve for EPS.
5
Load test and verify
With the battery charged, we temporarily disconnect the main AC supply to simulate a grid outage. The EPS circuits should pick up within 20ms. We test with actual loads — lights, appliances — and verify stable voltage and frequency on the inverter display. For changeover switches, we test the full switchover sequence. Grid reconnection is then tested to confirm automatic return to normal operation.
EPS installation pricing
Pricing depends on which configuration type you need. All prices include labour, materials, Part P certification, neutral-earth bond, inverter configuration, load testing, and a written post-installation report.
Socket or dedicated circuit
From £495
EPS wall socket (£495) or dedicated EPS sub-board (£995). Both include cabling from inverter EPS terminals, neutral-earth bond, circuit transfers, configuration, and test.
Types 1 & 2 · Half day
Full house manual switchover
£1,295
Manual changeover switch between meter and consumer unit, neutral-earth bond, EPS wiring, configuration, and full test sequence.
Type 3 · Full day
Full house auto switchover
From £1,495
Automatic transfer switch (ATS), changeover wiring, neutral-earth bond, EPS configuration, and comprehensive test sequence.
Type 4 · Full day
All costs confirmed in writing before work begins. EPS work is carried out by Part P certified electricians. We include a post-installation report documenting the EPS circuit layout, changeover switch type, configuration settings, and test results. You receive a clear record of what was done and how to use your EPS system.
Inverter does not support EPS? If your current inverter is a string model without EPS capability, the first step is inverter replacement with an EPS-capable hybrid. We can quote the full job — inverter replacement plus EPS installation — as a single package.
How long will my battery last during an outage?
EPS duration depends on battery capacity, protected load, time of day, and battery reserve settings. With a dedicated EPS circuit protecting only essentials, a modest battery can last a full day or more. With full-house changeover, duration drops significantly unless you manage your loads.
If the outage occurs during daylight and your solar panels are generating, the battery recharges continuously — potentially extending EPS duration indefinitely for low loads.
Battery size
Protected load
250W
Lights, router, phone chargers
500W
+ TV, freezer, boiler
1,000W
+ multiple appliances
5 kWh
~18 hrs
~9 hrs
~4.5 hrs
10 kWh
~36 hrs
~18 hrs
~9 hrs
15 kWh
~54 hrs
~27 hrs
~13 hrs
Estimates assume 80% usable capacity with 20% battery reserve. During daytime solar generation, EPS duration extends significantly as panels recharge the battery. Hours shown are approximate and depend on battery health and actual load. Full-house changeover installations should size their load expectations accordingly — see how battery storage works for more detail.
Related pages
GivEnergy EPS not working
EPS-capable inverter but circuits go dark in a power cut. Neutral-earth bond, EPS configuration, and GivEnergy-specific settings.
Add an extra battery
Extending battery capacity increases EPS runtime. Understand what adding a second module involves and how it improves backup duration.
Inverter replacement
If your current inverter does not support EPS, replacement with a hybrid model may be the only route to backup power.
How battery storage works
Understand how solar batteries charge, discharge, and interact with the grid — essential background for sizing your EPS setup.
EPS installation across Yorkshire & beyond
We install EPS backup systems on-site across a wide coverage area from our Yorkshire base — including Leeds, Bradford, Wakefield, Harrogate, York, Sheffield, Huddersfield, Doncaster, Hull, Barnsley, Scunthorpe, Grimsby, Mansfield, Derby, Nottingham, Manchester, Darlington, and Middlesbrough. We also cover Cardiff in South Wales, where STS has a locally-based engineer — same-day to next-day on site.
EPS installation — frequently asked questions
An EPS wall socket is a single 13A socket wired from the inverter's EPS terminals — it powers one or two appliances during an outage. A dedicated EPS circuit is a separate sub-board protecting multiple circuits (lights, sockets, freezer, boiler). A full-house manual changeover switch lets you switch your entire consumer unit to battery power by turning a rotary isolator. A full-house automatic changeover switch does this automatically within milliseconds when the grid fails. Each option increases in coverage, complexity, and cost.
Most modern hybrid inverters support EPS: GivEnergy AIO, Sunsynk Hybrid, Growatt SPH/SPA, SolaX Hybrid G4, Fox ESS H1/H3, Lux Power, Alpha ESS, and Sigenergy. Standard string inverters do not support EPS — they shut down completely when the grid fails. Check your inverter documentation or the manufacturer's portal for an EPS or backup mode setting.
Almost always a missing neutral-earth bond. When the grid fails and EPS activates, the inverter output becomes an isolated island supply. Without a neutral-earth bond at the EPS sub-board or changeover point, RCDs trip because the earth reference disappears. This is a quick fix for a qualified electrician — adding the bond resolves the problem immediately. If your EPS goes dead in a real outage, our remote diagnostic confirms the cause before any work.
Yes, with a full-house changeover switch (manual or automatic). However, you need to manage your loads carefully — a typical 5 kWh battery will only sustain the whole house for a few hours if high-draw appliances are running. With full-house changeover, you get the flexibility to power everything, but you should avoid running electric showers, cookers, or heat pumps simultaneously to preserve battery life. A 10 kWh+ battery bank is recommended for full-house configurations.
Duration depends on battery size and load. At 500W of protected load: a 5 kWh battery lasts approximately 9 hours, a 10 kWh battery approximately 18 hours. During daylight, solar panels recharge the battery continuously — extending EPS duration significantly. Setting a 20% battery reserve ensures capacity is always available for EPS. See the duration table above for more examples.
An EPS wall socket costs £495. A dedicated EPS circuit starts from £995 including wiring, neutral-earth bond, and configuration. A full-house manual changeover switch starts £1,295. A full-house automatic changeover switch starts from £1,495. All prices include Part P certification, load testing, and a written post-installation report. Costs are confirmed in writing before work begins — see our full price list.
When the grid fails and EPS activates, the inverter's EPS output becomes an isolated island supply — it is no longer connected to the grid's earth reference. A neutral-earth bond establishes a local earth reference at the EPS sub-board or changeover point so that RCDs can function correctly. Without this bond, RCDs trip immediately and the EPS circuits go dead. This is the single most common reason EPS does not work during a real power cut.
Yes — STS installs EPS on any compatible hybrid inverter regardless of brand. This includes GivEnergy, Sunsynk, Growatt, SolaX, Fox ESS, Lux Power, Alpha ESS, Sigenergy, and others. The installation process is the same in principle: EPS wiring, neutral-earth bond, and portal configuration. Contact us with your inverter model to confirm compatibility before booking.
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Ready to add backup power?
Whether you want a single EPS socket, a dedicated circuit protecting your essentials, or full-house changeover for complete coverage — we assess, quote, and install. All work is Part P certified, tested on-site, and documented in writing.
- EPS socket £495 · Dedicated circuit £995 · Manual changeover £1,295
- Automatic changeover from £1,495 · All Part P certified
- Written report with configuration details and test results
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