FOX ESS KA10.5 - single-phase AC-coupled inverter 10.5 kW.

FOX ESS KA10.5 is the most powerful single-phase AC-coupled inverter in the range: 10.5 kW, high-voltage LiFePO₄ battery 85–480 V, charge and discharge current 50 A. Efficiency 97.8%, output current 45.7 A, generator support, Wi-Fi and LAN. 5-year warranty.

Single-phase business: shop, workshop, bakery

Ten and a half kilowatts of uninterrupted power on one phase is no longer a domestic scale. Such a unit is most often bought not for a house but for a small commercial premises fed from a single-phase supply.

A grocery shop with refrigerated displays, a hairdresser's, a dental surgery, a bakery, a small production unit, a server room — all share one trait: stopping work costs money by the minute, and a three-phase line often simply does not exist.

For retail the calculation is especially plain. One prolonged summer outage means a defrosted display and written-off stock. The cost of such a loss not infrequently exceeds half the price of the entire backup system, so payback is counted not in years but in incidents.

AC coupling is convenient here for a further reason: it requires no shutdown of the premises for installation. A backup group is separated in the consumer unit, the inverter is connected in parallel, and trading continues.

The ceiling of single-phase backup capability

Forty-five point seven amperes is the limit of what can realistically be drawn from one phase. Above that level, any solution requires a three-phase supply, and arranging one is a different story in both time and cost.

Do check your own supply before purchase. A 40-ampere breaker will limit the system regardless of what the inverter's datasheet says; the cable from the pole must correspond too.

If the supply is smaller than you would like, there is a workable compromise: the inverter can operate with a cap on grid consumption, making up the difference from the battery. The supply is then not overloaded, and peak loads are covered by the storage.

Technical specifications

• rated power 10.5 kW, single phase;

• type: AC-coupled, connected on the AC side;

• high-voltage LiFePO₄ battery, range 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;

• Wi-Fi and LAN interfaces;

• 5-year manufacturer warranty.

Starting headroom: 47.7 amperes

The difference between nominal and maximum current is two amperes — about four per cent. For a commercial site that reserve has a concrete purpose.

Refrigeration equipment is the main source of starting currents in a shop. Compressors do not switch on in step, and at certain moments two or three of them start almost simultaneously. It is for such coincidences that the reserve exists.

Relying on it alone, however, is unwise. The proper solution for a site with many compressors is to stagger their starts through control equipment. That extends the life of both the equipment itself and the backup system.

A battery as an investment that works daily

A backup system that engages only during faults sits idle most of the time. Storage based on the KA10.5 works differently: it is in use every day, even when the grid is perfectly fine.

Charging during night hours at the reduced rate and discharging in the daytime peak produces a daily saving on the difference between rates. For a commercial consumer working precisely in daytime, that difference is appreciable.

The second daily function is smoothing peaks in own consumption. When air conditioning, equipment and lighting run at the same time, the battery takes the top of the load, and the supply does not approach its limit.

A charge current of 50 amperes with a high-voltage stack means the night window is used in full: the battery gathers the volume required within a few hours of the off-peak rate.

For a shop or workshop on one phase this is the maximum backup capability available without moving to three phases. Write to us with your equipment list and daily operating schedule: we will size the battery to the real profile and show how quickly the system earns its cost.