Fox ESS H1-5.0kW + CQ7 21kWh: A Complete UK Solar Storage Package
Pairing a hybrid inverter with the right battery is the single biggest decision behind any modern solar installation — get it wrong and you cap how much of your own generation you can ever use. The new Fox Bundle H1-5.0kW Hybrid Inverter + CQ7 21kWh Storage Package (Part No: FE-5.0-CQ7-21) solves the matching problem in one box: a Fox ESS H1 5.0kW Gen 2 hybrid inverter shipped alongside a three-module CQ7 high-voltage LiFePO₄ battery stack delivering 21.06kWh of usable energy storage.
It is aimed at UK homeowners moving from a small first-battery purchase to a properly sized whole-home storage system — typically those with 4–6kWp of PV, an EV on the drive, a heat pump, or a time-of-use tariff like Octopus Go, Cosy or Intelligent Octopus. This guide walks through what is in the box, how the CQ7 architecture scales, how the Fox ESS app gives you everything you need to run it day to day, and where this bundle sits against the wider H1 inverter range.
"Buy the bundle once, scale the battery later — the CQ7 stack supports up to seven modules on a single H1 inverter, so 21kWh today can become 49kWh tomorrow without changing the inverter."
How the Bundle Works: Inverter, Master, Slaves
The bundle is a matched set built around the high-voltage CQ7 architecture. Every CQ7 stack uses one Master module (which contains the Battery Management Unit, switchgear and CAN communication) plus one or more Slave modules (battery cells only, no controller). The H1 inverter handles solar conversion, grid interaction and EPS backup — and orchestrates the stack via the Master.
H1 5.0kW Hybrid Inverter (×1)
Fox H1 5.0kW Gen 2 single-phase hybrid inverter with dual MPPT, EPS backup output, IP65 rating and built-in WiFi for monitoring. Up to 97.8% peak efficiency.
CQ7 Master Module (×1)
The system controller: 7.02kWh LiFePO₄ cell module integrated with the BMU, switchgear and CAN interface. Every CQ7 stack starts with one Master.
CQ7 Slave Modules (×2)
Two 7.02kWh slave expansion modules connect in series with the Master, taking total stored energy to 21.06kWh. Slaves contain cells only — no duplicated electronics.
Plug-and-Play Stack
Modules clip together with pre-routed power and CAN connections. The H1 detects the stack on commissioning — no manual battery sizing, no separate battery cabinet.
Why This Package Makes Sense for UK Homes
UK residential solar installations are increasingly being right-sized for export tariffs, time-of-use import deals and EV charging — not just self-consumption. A 5.0kW hybrid inverter plus 21kWh of high-voltage LiFePO₄ storage gives a household the headroom to do all four of the following at once:
- Charge from cheap off-peak windows (Octopus Go, Cosy, Intelligent Octopus) and discharge through the evening peak
- Run a heat pump or EV charge cycle from stored energy rather than the grid during the 16:00–19:00 peak
- Provide whole-essential-load backup via EPS when the grid drops — fridges, boiler, lighting, broadband
- Scale up later without replacing the inverter — the H1-G2 supports up to seven CQ7 modules (49.14kWh) on a single stack
CQ7 Stack Sizing With the H1-G2 Inverter
The CQ7 is designed to scale, so it is worth understanding where this 21kWh bundle sits inside the wider sizing envelope. With an H1-G2 (or K Series) inverter, a single CQ7 stack supports two to seven modules:
| Configuration | Modules | Usable Capacity | Typical Use Case |
|---|---|---|---|
| Minimum stack | 1 Master + 1 Slave | 14.04kWh | Small terraced home, low evening peak |
| This bundle | 1 Master + 2 Slaves | 21.06kWh | 3–4 bed, EV or heat pump, ToU tariff |
| Larger family | 1 Master + 3 Slaves | 28.08kWh | Heavy evening load, two EVs |
| Maximum (1-phase) | 1 Master + 6 Slaves | 49.14kWh | All-electric home, full backup brief |
You commit to the H1 5.0kW inverter once. The battery stack itself grows simply by adding Slave modules later — there is no re-commissioning, no second inverter, no second cabinet footprint.
Fox ESS CQ7 in Action
The short video below from Fox ESS walks through the CQ7 high-voltage storage battery, its modular construction and how it scales:
What's In the Bundle
The package ships as one SKU but is built from three matched components that are also available individually if you need spares, replacements or are scaling an existing CQ7 stack:
Fox Bundle H1-5.0kW Hybrid Inverter + CQ7 21kWh Storage Package
The complete matched set: H1 5.0kW Gen 2 hybrid inverter plus one CQ7 Master and two CQ7 Slave modules for 21.06kWh of high-voltage LiFePO₄ storage. Part No: FE-5.0-CQ7-21.
£4,770.00 inc. VAT
Fox ESS CQ7 High Voltage Battery Master Module 7.02kWh
The system controller for every CQ7 stack: a 7.02kWh LiFePO₄ cell module with integrated BMU, switchgear and CAN communications. Each stack requires exactly one Master. Part No: FE-CQ7-M.
£4,170.00 inc. VAT
Fox ESS CQ7 High Voltage Battery Slave Module 7.02kWh
7.02kWh LiFePO₄ expansion module adding capacity to any existing CQ7 stack. Cells only — no controller — keeping each added module light, cost-effective and quick to install. Part No: FE-CQ7-S.
£4,170.00 inc. VAT
Key Technical Specifications
| Specification | H1-5.0 Hybrid Inverter | CQ7 Battery Stack (21kWh) |
|---|---|---|
| Rated AC Output | 5.0kW | — |
| Peak Efficiency | 97.8% | — |
| MPPT Trackers | 2 (Dual MPPT) | — |
| EPS Backup Output | Yes — built-in | — |
| Battery Chemistry | — | LiFePO₄ (LFP) |
| Module Capacity | — | 7.02kWh per module |
| Total Bundle Capacity | — | 21.06kWh (3 modules) |
| Max Stack on H1-G2 | — | 49.14kWh (7 modules) |
| Depth of Discharge | — | 90% |
| Voltage Class | 1-phase, 230V | High Voltage |
| Ingress Protection | IP65 | IP65 |
| Safety Features | Type II SPDs, AFCI | Fire suppressant, battery warming |
| Communications | WiFi, optional Ethernet | CAN (via Master) |
| Monitoring App | Fox ESS / Fox Cloud | Fox ESS / Fox Cloud |
Managing the System with the Fox ESS App and Fox Cloud
Hardware is only half the story. The H1 + CQ7 system is designed to be lived with day-to-day through the Fox ESS app and Fox Cloud web portal — both connect to the same online command centre, with the Cloud running through a browser and the app syncing seamlessly on iOS and Android. Once the installer commissions the system, you can run almost everything from your phone.
What you can do from the Fox ESS app
The app is built around four jobs: see what is happening right now, look back at how the system has performed, fine-tune the schedule, and integrate with smart tariffs and third-party platforms.
Live solar generation, battery state-of-charge, grid import/export and house load — at a glance from anywhere.
Daily, monthly and annual energy flows so you can see exactly how much you self-consumed, exported and stored.
Set time-of-use windows to force-charge from cheap off-peak rates and discharge during expensive evening peaks.
Track stack health, see active alarms and receive push notifications if anything in the CQ7 stack needs attention.
Reserve a percentage of battery capacity for grid outages, or run a self-use-only profile in normal operation.
Works with Capture AI, Kraken, Octopus, Axle Energy VPPs and Enode-linked clean-tech apps for automatic optimisation.
For households on a dynamic tariff, the most useful integration is Capture AI, which forecasts solar generation, watches your tariff rate and automatically schedules charge and discharge windows to minimise your bill — and can enrol the battery into grid flexibility services for extra return. If you would rather aggregate with a virtual power plant, Axle Energy bundles Fox systems together to offer balancing services to the grid operator. Either path is configured inside the same Fox app.
Other H1 Hybrid Inverter Options
The bundle uses the 5.0kW H1, which suits a typical 3–4 bed UK home with 4–6kWp of PV. If your generation profile or single-phase loop limit is different, the wider H1-G2 family covers 3.0kW up to 6.0kW — all share the same EPS backup, dual MPPT design, IP65 rating and CQ7 compatibility:
Fox ESS H1 3.0kW Hybrid Inverter With EPS Gen 2
Entry single-phase H1 for smaller PV arrays. Dual MPPT, EPS backup, IP65, WiFi monitoring and full CQ7 high-voltage battery compatibility.
£850.00 inc. VAT
Fox ESS H1 3.7kW Hybrid Inverter With EPS Backup
The 3.7kW H1-G2 sits between the 3kW and 5kW models — a common pick for modest PV arrays on tight DNO export limits. Dual MPPT, EPS, IP65 and WiFi.
£870.00 inc. VAT
Fox ESS H1 5.0kW Hybrid Inverter With EPS Gen 2
The unit included in this bundle. 5.0kW output, 97.8% peak efficiency, dual MPPT, EPS backup, IP65 housing — the workhorse of the H1-G2 range.
£895.00 inc. VAT
Fox ESS H1 6.0kW Hybrid Inverter With EPS Gen 2
The largest single-phase H1-G2. 6.0kW for larger PV arrays or heavier evening loads — 97.8% efficiency, dual MPPT, EPS backup, full CQ7 support.
£930.00 inc. VAT
Frequently Asked Questions
What is the difference between the CQ7 Master and Slave modules?
The Master (FE-CQ7-M) contains the Battery Management Unit, switchgear and CAN communication interface that controls the entire stack — every CQ7 system has exactly one Master. The Slave (FE-CQ7-S) is a cell-only expansion module that adds 7.02kWh of LiFePO₄ capacity without duplicating the electronics. This 21kWh bundle includes one Master and two Slaves.
Can I add more battery modules to this bundle later?
Yes. The H1-G2 inverter supports up to seven CQ7 modules per stack, giving a maximum 49.14kWh on a single H1. This bundle starts you at three modules (21.06kWh) — you can add Slave modules later without changing the inverter or re-commissioning the stack.
Does the bundle include solar panels?
No. The bundle is the inverter and battery storage half of a PV installation. PV panels, mounting, cabling and installation labour are specified separately by your MCS installer so the array can be tailored to your roof.
Will it keep the lights on during a power cut?
The H1 includes an Emergency Power Supply (EPS) output that switches to battery-backed power when the grid fails, supplying essential circuits wired to the EPS feed. This is a single-circuit backup rather than whole-home — for whole-home backup, Fox ESS sells the EPS-BOX SP backup gateway as a separate accessory.
What tariffs work best with the H1 + CQ7 system?
Any time-of-use tariff with cheap off-peak windows pairs well — Octopus Go, Octopus Cosy, Intelligent Octopus Go, OVO Charge Anytime, and dynamic tariffs via Capture AI. The Fox ESS app can be set to force-charge during cheap windows and discharge through expensive peaks.
Is the system MCS-certified and eligible for VAT zero-rating?
Fox ESS H1 hybrid inverters and battery storage are eligible products for MCS-certified installations and qualify for 0% VAT on battery and solar installations under current HMRC rules until 31 March 2027 — subject to installation by an MCS-certified installer. Your installer is responsible for confirming MCS paperwork on your specific job.
Standards, Certifications & Partner Integrations
Ready to Order the Fox H1 + CQ7 21kWh Bundle?
One SKU. One delivery. A matched inverter-and-storage package that scales to 49kWh on the same H1 you order today.