Deye SUN-3K-SG04LP1-EU (3 kW) - single-phase hybrid inverter

Where this model fits and where it does not

The SUN-3K-SG04LP1-EU is the entry point of the hybrid range: 3000 W of continuous power and a 24 V battery bus instead of the usual 48 V. It belongs in an apartment with its own meter, a summer house, a small cottage or an office with a handful of desks, where the goal is not full energy independence but surviving an outage without losses: a fridge, a gas boiler with its circulation pump, lighting, a router, laptops and a TV together rarely pull more than 1 to 1.5 kW. For such a site the unit accepts a photovoltaic array of up to 4800 W, which is enough to feed the house during the day and charge the battery at the same time. Where it clearly does not belong: it cannot serve a three-phase supply at all, an electric boiler, an instantaneous water heater or a welder above 3 kW will not run, and the idea of starting with a 3K and later growing to 20 kWh of storage does not work, because the 24 V bus physically limits both power and sensible capacity. If the house has a resistive water heater or an electric hob, look straight at the 5 to 6 kW models, otherwise the inverter will have to be replaced within a season.

The 24 V battery bus is the detail buyers miss most often

Nominal battery voltage here is 24 V with a working range of 20 to 30 V, and that single line matters more than anything else in the datasheet. The vast majority of lithium modules in this catalogue are 48 V units — the whole SE-F, RW-F and SE-G families — and none of them connects to this inverter: the BMS simply will not find a compatible voltage, and attempts to build 24 V out of half a module end badly. The officially matched module is the Deye RW-L2.5 (item 2090) at 25.6 V and 2.56 kWh, and from the same catalogue the SE-F5-24-A (item 1939) fits too, giving 5.12 kWh in a 24 V package. Rated charge and discharge current is 140 A, which at 25.6 V works out at roughly 3.5 kW, so the battery delivers exactly as much as the inverter itself can produce and no bottleneck appears between them. Lead-acid banks, including AGM and GEL, are supported as well, but for daily cycling they are a clearly worse choice in terms of service life and make sense only as a stopgap on batteries you already own.

A single 18 A MPPT and how to build the array around it

This model has one photovoltaic input: a single independent MPPT with one string, a maximum operating current of 18 A and a short-circuit current of up to 27 A. In practice every panel must face the same direction with the same tilt, because two roof planes on one tracker mean the shaded or dimmer half drags the whole string down. The MPPT window runs from 150 to 425 V against a maximum input of 500 V and a start-up voltage of 125 V, so a typical string is eight to eleven modern modules in series — and in hard frost it is worth checking open-circuit voltage so the array does not hit the 500 V ceiling. Rated array power is 4800 W, yet the manufacturer explicitly allows up to 6000 W of panels to be connected: that oversizing pays for itself on overcast mornings and through winter, when real output is half of what the nameplate suggests. Rated PV voltage for this platform is 370 V, and that is where conversion efficiency peaks, so the string is best sized to sit near that figure during the working day rather than near the 150 V floor.

What 3 kW actually powers, and what the ten-second peak is for

Continuous output is 3000 W with 3300 VA of apparent power, the point beyond which the inverter goes into overload, so the load list is worth drawing up honestly in advance. At 230 V the rated output current is about 13 A with a maximum of 15 A, which means a modern fridge, a gas boiler, several lighting circuits, a router, a TV and even an 800 W microwave coexist comfortably, while a 2 kW kettle together with a washing machine will trip it. Off grid the unit allows a short peak of twice the nominal figure — 6000 W for ten seconds — which covers the inrush of a fridge compressor, a circulation pump or a small borehole pump, but not sustained operation at that level. Grid pass-through is rated at 35 A, so while mains power is present up to 8 kW flows through the inverter to the house, and the 3 kW limit applies only to what it generates itself from panels and battery. That distinction surprises most buyers: with the grid up the house behaves exactly as before, and the 3 kW ceiling is felt only during an outage.

Behaviour when the grid fails, and working with a generator

The switch to island mode is automatic and needs no intervention, and this is precisely why a hybrid is bought instead of a grid-tie unit, which shuts down together with the mains the moment a phase disappears. A dedicated generator input is provided: the inverter can accept a petrol or diesel set, charge the battery from it and bridge a gap when there has been no sun for several days. That matters most in winter, when a 4.8 kW array yields barely a fifth of its summer harvest while outages grow longer — the generator refills the storage in an hour or so and stops, instead of running under the window all night. Communication with the battery BMS runs over RS485 or CAN with automatic protocol adaptation, so the inverter sees the real state of charge and cell temperature rather than guessing from voltage. One practical caveat: the generator needs a clean waveform and a sensible power margin, otherwise synchronisation will be refused — cheap inverter sets with heavily distorted output are frequently rejected.

Mounting, cooling and tolerance to conditions

The enclosure is rated IP65 and is cooled by natural convection with no fan, hence a typical noise level below 30 dB — the unit is barely audible even in a living space. The absence of a fan has a second benefit: there are no moving parts to clog with dust or wear out, which means less maintenance over the years of service. At 376 by 470 by 241.5 mm and 17.6 kg it can be lifted onto a wall by two people without hoisting gear, though the wall should be solid masonry rather than a plasterboard partition. The operating range spans -40 to +60 °C, but power derating begins above +45 °C, and that must shape the choice of location: a south-facing wall in full summer sun will cost output during the very best hours. Installation altitude is allowed up to 2000 m with humidity to 100 % non-condensing; panels connect through MC4 connectors and the DC isolator is built in, so no separate DC switch is needed.

Protection, certification and monitoring

The protection set is complete for a domestic installation: earth-fault and grid monitoring, DC reverse-polarity protection, short-circuit protection, an all-pole sensitive residual current monitoring unit and type II surge arresters on both the DC and the AC side. The topology is transformerless with overvoltage categories OVC II on the DC side and OVC III on the AC side, matching an ordinary connection to a domestic supply through the main distribution board. Certification covers IEC/EN 62109-1/2, IEC 61727, IEC 62116, EN 50549 and G99, which is enough to register the installation formally, including for feed-in arrangements and approval by the grid operator. Control is handled from a colour touch display on the unit plus a mobile app, while communication runs over RS485, RS232 or CAN; Wi-Fi, LAN, GPRS or 4G are added as a separate module such as the Logger Stick (item 2104). The manufacturer warranty is five or ten years depending on country and installation conditions, which is worth clarifying before the purchase rather than after it.

How it differs from its neighbours in this catalogue

Its closest relatives here are the SUN-5K-SG03LP1-EU (item 2050) and the SUN-6K-SG05LP1-EU (item 2053): both single-phase hybrids, but already on a 48 V bus, with two MPPTs and arrays of up to 6500 and 7800 W respectively. The difference is not only in kilowatts — a 48 V bus opens up the entire SE-F and RW-F battery range, so storage can grow almost without limit, whereas the 24 V design remains a small-system solution. If you need to run a water heater, an air conditioner and a washing machine at the same time, take the 2053 or the larger 2047 or 2059, which were built for exactly that. Conversely, if the task is keeping a fridge, a boiler and the lights alive at a summer house or in a flat, paying for 8 kW makes no sense: this model covers the scenario fully and takes up less wall. It should also not be confused with the grid-tie SUN-3K-G (item 2083): that one is also 3 kW, half the weight and simpler to install, but it supports no battery at all and shuts down when the grid fails, so it provides no backup by design.

If you are unsure whether 3 kW is enough for your particular list of appliances, send it over and we will work out both the power you need and a sensible battery size.