The second-generation Fox ESS EVO 10E puts a hybrid inverter and a 10.24kWh LiFePO₄ battery in one cabinet. For installers, that means one unit to lift, one set of terminations to make and one product to commission, instead of matching an inverter to a separate battery stack.
The EVO 10E comes in four single-phase versions — 3.7kW, 5kW, 8kW and 10kW — and every one of them carries the same integrated battery. You choose the model on inverter output, PV array size and grid connection; storage is constant at 10.24kWh nominal and 9.73kWh usable at 95% depth of discharge.
This guide covers what Gen 2 changes, where the EVO fits in real jobs, how to size it, the installation sequence, and how to turn its built-in EPS output into whole-home backup with the Fox ESS EPS-BOX-SP gateway.
Meet the EVO ecosystem
Fox ESS’s own introduction walks through the EVO family and how the unit sits within the wider Fox ecosystem of monitoring, backup and integrations.
Introduction to the Fox EVO EcoSystem. Watch on YouTube
What the EVO 10E Gen 2 actually is
Inside the enclosure you have a non-isolated hybrid inverter with two or three MPPT inputs, a 10.24kWh LFP battery with its own BMS, intelligent air cooling and a battery warm-up function. The cabinet measures 584 × 1009 × 197mm and weighs 108kg, and it can be wall- or floor-mounted.
Inverter section above, integrated 10.24kWh LiFePO₄ battery below, in a single IP66 cabinet.
The headline change for Gen 2 is how the system grows. The first-generation EVO scaled by installing additional complete EVO units in parallel through an EMS. Gen 2 adds a DC battery expansion route: the manufacturer datasheet lists support for up to three ET10 expansion batteries (10.24kWh each) connected to one EVO, so you can add storage without adding another inverter.
Availability check before you design around expansion. UK supply information currently states that ET10 expansion units are expected from December 2026, and that AC parallel operation of multiple EVO units is not currently available in the UK. Design today’s job around a single EVO, and confirm ET10 stock with us before promising a customer a specific expansion date.
How the energy flows
PV in
Strings land on 2 MPPTs (3.7kW and 5kW) or 3 MPPTs (8kW and 10kW), each taking 20A with an 80–550V operating window and an 80V start-up voltage. Low start-up means earlier generation on dull mornings.
Charge the battery
Surplus PV charges the integrated battery at up to 10kW, at 97.33% PV-to-battery efficiency at full load. Without PV, the EVO can charge from the grid on a cheap off-peak window.
Supply the home
The inverter serves household load from PV first, then battery, then grid, with up to 97.62% conversion efficiency. Export limit control is built in for DNO-imposed caps.
Back up when the grid fails
The EPS output takes over in under 4ms, with 100A load-start capability for 2 seconds. Add the EPS-BOX-SP to extend backup from a dedicated circuit to the whole consumer unit.
Where the EVO 10E fits: applications for installers
Because storage is fixed and the inverter output varies, the EVO maps neatly onto common UK domestic jobs. These are the scenarios where it earns its place on a quote.
New solar plus storage
The standard job. A 5kW EVO with 2 MPPTs covers a typical east/west or south-facing array up to 16kWp of panels, with the battery and inverter going in as a single lift and a single set of terminations.
Battery-only tariff shifting
Fox ESS confirms the EVO can be installed with or without PV. For homes on a time-of-use tariff, it charges overnight and discharges through the evening peak, and it’s ready for PV to be added later.
Large or split roofs
The 8kW and 10kW models add a third MPPT and accept up to 20kWp of PV, which suits three orientations, dormers or a garage roof. Fox ESS quotes a 200–300% PV oversize ratio for capturing shoulder-hour generation.
Whole-home backup
Pair the EVO with the EPS-BOX-SP for automatic grid isolation and backup of every circuit in the consumer unit — useful for rural properties, home workers and customers on the end of a weak supply.
Outdoor or tight sites
IP66, intelligent cooling and a warm-up function that extends operation down to −25°C let you mount it on an external wall when the garage, loft or utility room won’t take a 108kg cabinet.
Heat pump and EV homes
SG Ready, dry contact, meter and EMS interfaces, plus Fox’s integrations with Capture AI, Axle Energy’s virtual power plant, Kraken and Enode, help higher-demand homes shift load and earn from flexibility services.
Installer notes before you quote
- G98 or G99. The 3.7kW model is rated at 16.0A at 230V, right at the 16A-per-phase G98 limit. The 5kW, 8kW and 10kW models exceed it, so plan for a G99 application or an export limit agreed with the DNO.
- Weight and fixings. Every model weighs 108kg. Check the wall construction, plan the lift with suitable equipment, or use the floor-mounted option.
- Battery location. Follow PAS 63100 guidance for where a home battery can be sited, and the manufacturer’s clearances.
- PV voltage. Keep string Voc below 600V at the coldest expected temperature — voltages above 600V may damage the inverter.
- Protection built in. AFCI, DC switch, Type II surge protection on both DC and AC sides, insulation resistance and leakage current monitoring are all integrated, and the battery has a fire protection function.
- Wiring standards. Installation and commissioning to BS 7671 and Fox ESS’s instructions, by a competent installer.
Choosing the right EVO 10E model
The battery is identical on every model, so the comparison is all about the inverter side and the grid route.
| Model | EVO10E-3.7-H | EVO10E-5-H | EVO10E-8-H | EVO10E-10-H |
|---|---|---|---|---|
| Rated AC output | 3,680W | 5,000W | 8,000W | 10,000W |
| Rated current at 230V | 16.0A | 21.7A | 34.8A | 43.5A |
| Likely grid route | G98 | G99 / export limit | G99 / export limit | G99 / export limit |
| MPPTs / strings | 2 / 1 each | 2 / 1 each | 3 / 1 each | 3 / 1 each |
| Max PV array | 16kWp | 16kWp | 20kWp | 20kWp |
| Max PV input power | 13,700W | 15,000W | 18,000W | 20,000W |
| EPS backup output | 3,680VA | 5,000VA | 8,000VA | 10,000VA |
| Max grid import (per phase) | 32.0A | 40.0A | 63.0A | 63.0A |
| Max efficiency | 97.60% | 97.62% | 97.62% | 97.62% |
| Battery (all models) | 10.24kWh nominal, 9.73kWh usable, LiFePO₄ | |||
As a rule of thumb: the 3.7kW suits smaller arrays and the simplest G98 connection; the 5kW is the everyday domestic model; the 8kW and 10kW are for larger, multi-orientation roofs, bigger evening loads, and customers who want more headroom on backup.
Installing the EVO: the sequence
Fox ESS’s installer video shows the physical install from start to finish. Watch it before your first EVO job, then use the steps below as a planning checklist.
How to install the Fox EVO. Watch on YouTube
Survey and grid paperwork
Pick the model from the array design and household load, then confirm the G98 notification or G99 application, and any export limit, with the DNO before the install date.
Location and mounting
Choose a PAS 63100-compliant location, check clearances, and decide between wall and floor mounting for the 108kg cabinet. Outdoor walls are fine thanks to IP66.
Terminations
Land PV strings on the MPPTs, the grid connection (L/N/PE), the EPS output to the backed-up circuit or EPS-BOX-SP, and the meter or CT for export control.
Commission and hand over
Connect via WiFi, LAN or Bluetooth, register the system on FoxCloud 2.0, set export limits and tariff schedules, and walk the customer through the app.
Whole-home backup with the EPS-BOX-SP
The EVO’s built-in EPS output only powers what you wire to it — typically a dedicated sub-board or a few essential circuits. The Fox ESS EPS-BOX-SP is a single-phase backup gateway that sits between the incoming supply, the EVO and the consumer unit, so the battery and solar can feed every circuit in the house during a power cut. Fox ESS lists the EVO among its compatible single-phase inverters.
Normal operation
The grid supplies the home as usual and the EVO charges and discharges normally. The gateway is transparent to the system.
Grid fails
The gateway detects loss of voltage, isolates the property from the network, and reconnects the consumer unit to the EVO’s EPS output in roughly 2–3 seconds.
Island mode
The whole house runs on battery and PV, with no back-feed onto the DNO’s cables. RS-485 communication reports the status to FoxCloud.
Grid returns
Once the supply is stable, the gateway reconnects automatically. The homeowner doesn’t need to do anything.
| Backup option | EVO EPS output only | EVO + EPS-BOX-SP |
|---|---|---|
| Circuits backed up | Dedicated EPS circuit or sub-board | Whole consumer unit |
| Changeover time | Under 4ms | Approx. 2–3 seconds |
| Grid isolation | Inverter anti-islanding | Automatic isolation at the supply point |
| Rewiring of circuits | Essential loads moved to EPS board | None — gateway sits ahead of the consumer unit |
| Gateway rating | — | 100A, IP65 metal enclosure, −25 to 60°C |
| Best for | IT, fridge, lighting and boiler circuits that can’t blink | Customers who want the whole house to keep working |
Load management still matters. The gateway is rated to 100A, but in an outage the house can only draw what the EVO’s EPS output provides — from 3,680VA on the 3.7kW model up to 10,000VA on the 10kW. Electric showers, ovens and fast EV charging can exceed that, so agree with the customer which high-draw loads should be avoided during a power cut, and consider the 8kW or 10kW model if backup is a priority. The EPS-BOX-SP is single-phase only.
Shop the system
Fox ESS
EVO 10E Gen 2 All-in-One Hybrid Inverter with 10.24kWh Battery
Choose 3.7kW, 5kW, 8kW or 10kW single-phase output, each with the same 10.24kWh LiFePO₄ battery. IP66, EPS backup and FoxCloud 2.0 monitoring in one cabinet.
From £4,050 inc. VAT
Fox ESS
EPS-BOX-SP Single Phase Whole-Home Backup Gateway
Turns the EVO’s EPS output into whole-home backup with automatic grid isolation. 100A rating, IP65 metal enclosure, fanless and suitable for retrofit.
£520 inc. VAT
Full specification: common to all models
| PV input | |
| Max input voltage | 600V |
| Start-up / nominal voltage | 80V / 360V |
| MPPT operating range | 80–550V |
| Max input / short-circuit current | 20A / 25A per MPPT |
| Max MPPT input power | 8,000W per MPPT |
| Battery | |
| Chemistry | LFP (LiFePO₄) |
| Energy | 10.24kWh nominal, 9.73kWh usable |
| Depth of discharge | 95% |
| Max charge power | 10,000W |
| DC expansion | Up to 3 × ET10 (check UK availability) |
| AC and EPS | |
| Grid connection | Single phase, 220/230/240V, L/N/PE, 50/60Hz |
| Power factor | 1 (0.8 leading to 0.8 lagging) |
| THDi | <3% at rated power |
| EPS switch time | <4ms |
| EPS load start capability | 100A for 2s |
| EPS THDv | <3% with linear load |
| Efficiency | |
| Max / European | Up to 97.62% / up to 97.20% |
| PV to battery (full load) | 97.33% |
| Battery to AC (full load) | 96.40% |
| Physical and environmental | |
| Dimensions (W × H × D) | 584 × 1009 × 197mm |
| Weight | 108kg |
| Mounting | Wall or floor |
| Ingress protection | IP66 (outdoor use) |
| Operating temperature | −20 to 55°C; −25 to 55°C with warm-up |
| Cooling / noise | Intelligent air cooling / <45dB average |
| Standby consumption | <20W |
| Altitude | <4,000m (derating above 2,000m) |
| Protection and connectivity | |
| Protection | AFCI DC switch Type II SPD (DC and AC) Anti-islanding Earth fault Leakage current |
| Communication | Ethernet, EMS, meter, WiFi + LAN + Bluetooth, optional 4G, DRM, ripple control, USB, SG Ready, dry contact |
| Monitoring | FoxCloud 2.0 app and web portal |
| Export limit control | Yes |
The ET10 expansion battery
When it reaches UK stock, the ET10 is the add-on module for Gen 2. Each one adds 10.24kWh of LiFePO₄ storage at 204.8V nominal, with round-trip efficiency of at least 95%, IP66 protection and natural convection cooling. It measures 625 × 770 × 160mm, weighs 100kg and communicates with the EVO over CAN. With three ET10s, a single EVO reaches roughly 38.9kWh of usable storage.
Standards and certifications
Fox ESS UK lists a 12-year warranty for the EVO. Confirm the current warranty terms and registration requirements at the point of sale.
Installer FAQs
Is the EVO 10E Gen 2 single-phase or three-phase?
All four UK models are single-phase (L/N/PE). For whole-home backup, pair it with the single-phase EPS-BOX-SP gateway.
Can I install it without solar panels?
Yes. Fox ESS confirms the EVO can be installed with or without PV, so it works as a battery-only system on a time-of-use tariff, with the MPPTs ready for an array later.
Which model needs only G98 notification?
The 3.7kW model, rated at 16.0A at 230V, sits at the 16A-per-phase G98 threshold. The 5kW, 8kW and 10kW models exceed it and normally need a G99 application or an agreed export limit. Always confirm the route with the DNO.
Can I parallel two EVO units today?
The datasheet lists AC parallel operation of up to three units, but UK supply information currently states that parallel operation is not available. Plan around a single EVO and use ET10 batteries for extra storage once they arrive.
How much backup power will the customer get?
Backup output matches each model’s rating: 3,680VA (3.7kW), 5,000VA (5kW), 8,000VA (8kW) or 10,000VA (10kW). Duration depends on the load and the battery’s state of charge, with 9.73kWh usable from a full battery.
Does the EPS-BOX-SP replace the EVO’s EPS output?
No. It uses the EVO’s EPS output and routes it to the whole consumer unit, adding automatic grid isolation at the supply point. It can be retrofitted to an existing EVO install.
Can the EVO join smart tariffs and VPPs?
Fox ESS works with Capture AI for tariff-aware optimisation, Axle Energy for virtual power plant participation, and Kraken and Enode for supplier and app integrations. Check eligibility with the individual platform for each customer.
Quoting an EVO job?
Talk to the AIZO team about model selection, EPS-BOX-SP backup and trade pricing on Fox ESS systems.