OUT OF STOCK
Fox 9kW K Series Single Phase Hybrid Inverter
Fox ESS Fox 9kW K Series Single Phase Hybrid Inverter
Fox 9kW K Series Single Phase Hybrid Inverter
Fox ESS K Series — 7 kW to 10.5 kW on a single phase, with an 18 kVA AC input for grid charging.
The K Series is where Fox's single-phase hybrid range goes past what a normal domestic array needs and starts serving houses that have electrified everything. Seven to 10.5 kW of AC output, three or four MPP trackers, and up to 15 kW of PV.
Please read before ordering
About the Fox ESS K Series
The number that distinguishes it is the AC input: up to 18 kVA and 78.3 A. That is the rate at which it can pull from the grid to charge the battery, and it is far above the AC output rating. On an off-peak tariff that means a large battery fills inside the cheap window rather than running out of night.
EPS output matches the rated power with a 10 kW or 12 kW peak for 60 seconds, and up to ten units run in parallel. It is 450 × 527 × 208 mm and 29 kg, convection cooled and under 30 dB.
Which battery does this inverter take?
This inverter takes High voltage Fox ESS stacks.
This model has a battery voltage window of 85 – 480 V, a maximum charge or discharge current of 50 A, BMS communication over CAN / RS485.
A stack is one master module, which carries the BMS, plus matching slave modules of the same type. Module types are never mixed in one stack. These are the counts this inverter is listed for — Product Compatibility Fox ESS UK 2026, the module count range for this inverter family:
What we stock that fits this inverter:
String design, battery limits and what is in the box
The details that decide whether this unit suits the job:
- Battery window 85 – 480 V, 300 V recommended, 50 A charge and 50 A discharge, CAN and RS485.
- KH7, KH8 and KH9 have three MPP trackers; KH10 and KH10.5 have four. One string per tracker, 16 A each, 20 A Isc.
- Each PV string is limited to 3,300 W regardless of tracker count.
- AC input up to 18 kVA / 78.3 A for grid charging — check the supply and the protective device, this is well above the AC output rating.
- DC disconnection switch is optional on this range. AFCI optional. Surge protection Type II / Type II.
- Up to 10 units in parallel; EPS switch time under 20 ms.
- Certified to G99, EN 50549 and NRS 097-2-1.
- The KA variants are the AC-coupled versions of the same platform, without the PV input.
Where this hybrid earns its place
The K Series is specified most often for these jobs.
Things worth knowing about this listing
- CT clamps and a meter are included in the box.
- Register the installation with Fox ESS at fox-ess.com to activate the 10-year warranty. Unregistered, the cover is 5 years.
Fox ESS KH9 technical data
Ordered with this inverter more often than anything else
A hybrid is the middle of a system, not the whole of it. These are the parts our customers add most often:
Questions we get asked about this inverter
Why does the AC input rating matter?
It is how fast the inverter can charge the battery from the grid. At 18 kVA a 20 kWh battery fills in a little over an hour, which fits inside any off-peak window. An inverter whose AC input matches its output would take twice as long.
Three trackers or four?
KH7, KH8 and KH9 have three. KH10 and KH10.5 have four. Each takes one string at 16 A, and each string is capped at 3,300 W.
Is the DC isolator included?
It is optional on this range — check the specific SKU or budget for an external isolator.
What is the difference between KH and KA?
KH is the hybrid with a PV input. KA is the same platform as an AC-coupled battery inverter, for adding storage to an existing PV system.
Will 10.5 kW get through a G99 application?
It is a G99 application on a single phase and the answer depends on your DNO. Many approve it with an export limit. Apply before you buy.
Documents, advice and trade pricing
Every datasheet, certificate, installation manual and warranty document we hold for this product is in the Documents tab below. See the rest of our hybrid inverter range, our batteries and our solar panels, or email sales@clearraysolar.com if you would like us to check a battery pairing or a string design before you order.
Build your complete solar system
Everything you need in one place.
- Inverters
- Batteries
- Mounting Systems
- Cabling & Accessories
- Protection Devices
Delivery times vary by region:
- UK — 1-2 business days
- Highlands & Islands — 1-2 business days
Returns accepted within 14 days of delivery for unused items in original packaging.
