FOX ESS KH8 - single-phase hybrid inverter 8 kW.

FOX ESS KH8 is a single-phase hybrid inverter rated at 8 kW with three MPPT inputs and support for high-voltage LiFePO₄ batteries at 85–480 V. Charge and discharge current 50 A, peak efficiency 97.8%, nominal output current 34.8 A, generator operation. Mass 29 kg, 5-year warranty.

Eight kilowatts on one phase: where the limit lies

A single-phase supply has a physical ceiling. Eight kilowatts at 230 volts is nearly thirty-five amperes of continuous current, and few domestic connections are designed for that load with any margin.

So the first question before buying a KH8 concerns not the inverter but the meter and the cable from the pole. If you have a standard 25 amperes, the unit simply will not be able to deliver full power — not because of its own limits, but because of the supply.

Where the connection does allow it, eight kilowatts in single-phase form covers almost any private house: heat pump, borehole pump, water heater and kitchen at the same time, with no need to stagger switching.

Three MPPTs and 50 amperes of charge

Three independent tracking channels allow an 8–10 kilowatt array to be spread across several roof planes. This is not an abstract advantage: most private-house roofs simply do not offer one continuous section of that size with ideal orientation.

The charge and discharge current of 50 amperes is symmetrical in both directions. With a high-voltage battery that amounts to tens of kilowatts of exchange power, so neither charging from the panels nor discharging into loads runs into the inverter's limits.

In practice this means the battery fills in a sunny period at exactly the rate the surplus allows, and in the evening gives back as much as the house needs, without flattening peaks.

Technical specifications

• rated power 8 kW, single-phase output;

• three independent MPPT inputs;

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

• charge and discharge current 50 A;

• peak efficiency 97.8%, European weighted 97.4%;

• nominal output current 34.8 A, maximum 38.3 A;

• external generator support;

• mass 29 kg, 5-year warranty.

The generator as a third source

Generator support takes the system beyond the pairing of sun and battery. In winter, when daylight is short and cloud cover holds for weeks, panels may not keep up with replenishing the storage.

The inverter starts the generator automatically according to battery state of charge and stops it once the threshold is reached. The generator runs not continuously but in short sessions at high load — the most economical and least wearing regime for the engine.

For remote sites with an unreliable grid this is often the decisive argument: the system stays autonomous all year, not only in season.

What to allow for during installation

Twenty-nine kilograms call for a load-bearing wall. Brick and concrete take the standard fixing kit; aerated concrete or a timber-frame wall requires through-fixings with a spreader plate.

A high-voltage battery means direct current at up to 480 volts. Installation and servicing belong to a qualified electrician: the logic of low-voltage systems, where a mistake ends in a spark, does not apply here.

Leave the ventilation clearances around the enclosure specified in the manual. An eight-kilowatt hybrid dissipates a noticeable amount of heat in summer, and a unit squeezed into a recess will start derating precisely when the sun is strongest.

If your supply allows eight kilowatts on one phase, the KH8 will cover the house completely — with a battery and a backup generator. Send us your load list and supply rating: we will calculate the configuration and tell you honestly whether a three-phase solution would make more sense.