FOX ESS KH10.5 - single-phase hybrid inverter 10.5 kW.

FOX ESS KH10.5 is the most powerful single-phase hybrid in the KH series: 10.5 kW, four MPPT inputs, high-voltage LiFePO₄ battery 85–480 V. Charge and discharge current 50 A, efficiency 97.8%, output current 45.7 A, generator support. IP65, passive cooling, mass 29 kg, 5-year warranty.

Array oversizing: why more panels get installed

An experienced designer almost never installs exactly as many panels as the inverter's rating states. Standard practice is an excess of 20–30 per cent, and for 10.5 kilowatts that means an array of 13–14 kilowatts.

The logic is simple. A panel's datasheet output is reached only under laboratory conditions: 1000 W/m², a cell temperature of 25 °C, an ideal angle. In real life the array delivers its maximum for a few dozen hours a year, and spends all the rest of the time at 40–70 per cent.

Surplus panels lift that curve. Morning and evening, in winter, in overcast weather you gain noticeably more, while the short peak hours when the inverter limits output cost far less than the additional annual generation.

Four independent MPPTs make such oversizing safe and manageable: each group is limited separately, and a surplus in one orientation does not disturb the others.

The upper limit of a single-phase arrangement

Forty-five point seven amperes of nominal current is effectively the ceiling of what can be drawn from one phase in domestic form. The KH10.5 sits at the very top of the range.

Such a unit makes sense where no three-phase line exists and none will appear in the coming years, yet the capacity is needed now. This is a typical situation in older private developments and on remote holdings.

The mandatory condition is a supply agreed with the network at the corresponding capacity. Check this before purchase: no inverter can circumvent the limits of the breaker and the meter, and disappointment here surfaces only after installation.

Technical specifications

• rated power 10.5 kW, single phase;

• four independent MPPT inputs, tracking efficiency 99.9%;

• MPP range 80–500 V, maximum input voltage 600 V;

• high-voltage LiFePO₄ battery, 85–480 V;

• charge and discharge current 50 A;

• efficiency 97.8% peak, 97.4% European weighted;

• output current 45.7 A nominal, 47.7 A maximum;

• generator support, THD below 3%, silent operation;

• IP65, climatic category 4K4H, -25 to +60 °C;

• dimensions 450 × 527 × 208 mm, mass 29 kg.

The same enclosure, greater output

The dimensions and mass of the KH10.5 coincide entirely with the smaller models in the series: the same 450 × 527 × 208 millimetres and 29 kilograms. The manufacturer uses a single power platform across the whole range.

For the buyer this has two consequences. The first is installation uniformity: bracket, cable entries and space in the switchboard are identical, so changing model requires no rework. The second, more important, is that the larger models have less thermal headroom.

The same heatsink dissipates fifteen per cent more heat. On a hot day on an unshaded south wall, the KH10.5 will approach the derating threshold sooner than the KH9. The practical conclusion: for the top model the mounting location must be chosen with particular care — shade, airflow, free space below and above.

Fifty amperes of charge at 10.5 kilowatts

The battery charge current is the same across the series — 50 amperes. With a high-voltage stack that amounts to tens of kilowatts, amply sufficient even for the most powerful unit in the range.

At midday, when a thirteen-kilowatt array delivers its maximum, part of the energy goes to the house and the remainder straight to the battery, with no restriction from the inverter. A ten-kilowatt-hour charge is gathered in roughly an hour of peak.

Symmetrical discharge at 50 amperes means all that energy returns just as quickly in the evening. For a house with an evening consumption peak — when everyone is home and the hob, washing machine and lighting are all on — that is precisely what is needed.

The most powerful single-phase hybrid in the series — for those extracting the maximum from one phase. Send us your supply rating and roof area: we will check whether array oversizing is justified in your case and size the battery to your evening profile.