Deye SUN-3K-G (3 kW) - single-phase grid-tie inverter

What a grid-tie inverter does and what it does not

The SUN-3K-G is a grid-tie (on-grid) inverter: it converts the direct current from the panels into alternating current and feeds it to the house and the grid, but it supports no battery at all and has no separate output for island supply. That implies the single most important thing to understand before buying: when the power goes out it shuts down together with the grid, and the house is left without electricity even in bright sunshine. This is not a defect but a requirement of anti-islanding standards — an inverter may not energise a line that repair crews might be working on. The purpose of this model is different: cutting the electricity bill and exporting the surplus under a feed-in arrangement, and at that it is more effective than a hybrid, because none of its service life goes into charging and discharging a battery and the whole system costs considerably less. If what you actually need is backup during outages, look at the hybrid SUN-3K-SG04LP1-EU (item 2048) — the same rating, but with a battery channel.

The sites where three kilowatts is enough

Three kilowatts corresponds to an array of about 3.9 kW, which means seven to nine modern panels and roughly 20 m² of roof: a typical size for a flat with its own roof, a small house, a summer place or a shop where fridges and lighting run during the day. Over a year in this climate such an array yields roughly 3.5 to 4.5 MWh, and if most of that energy is consumed on site the bill falls by the corresponding amount with no switching or settings to manage. The economics work best where daytime consumption is steady: an office, a shop, a workshop, a house with air conditioning or a heat pump that runs in daylight hours. For a site that consumes more at night than during the day the benefit is smaller — the surplus goes to the grid at the export rate instead of offsetting your own consumption. Three kilowatts will not serve a three-phase supply and will not carry specific heavy loads on their own: this is a source for the building as a whole, not for a dedicated circuit.

One MPPT with a 70 to 500 V window: why that suits a small roof

There is a single tracker here, with 13 A of operating current, 19.5 A of short-circuit current and a maximum input of 550 V. Its main practical advantage is a very wide MPPT window: 70 to 500 V with a start-up voltage of just 80 V, so the inverter works even with a short string of three or four modules. On a small or awkward roof that is decisive — there is no need to find room for the textbook eight panels in a row, you fit as many as the roof allows. A wide window also means a longer working day: the inverter wakes earlier at dawn and keeps running later in the evening as array voltage falls. The limitation deserves equal attention: one tracker means one orientation and one tilt, so two roof planes should not be wired into this model, since the weaker group drags the stronger one down; for two orientations the catalogue offers the SUN-5K-G (item 2086) with two MPPTs.

97.5 % efficiency and under one watt at night

Maximum efficiency is 97.5 % with a European figure of 97.3 %, so less than a hundred watts turns into heat at three kilowatts — which is why this series needs no fan at all. Maximum power point tracking exceeds 99 % efficiency and output distortion stays below 3 %, so the inverter does nothing to degrade voltage quality in the house. Night-time self-consumption is under 1 W: a few kilowatt-hours a year, effectively nothing, and there is no sense in switching the unit off overnight. Rated output current is 13.7 A at 220 V and 13.1 A at 230 V with a 15 A maximum, so an ordinary 16 A circuit with its own breaker is enough for the connection. The few tenths of a per cent of efficiency that separate models in this series are invisible in practice — shading, dust on the panels and a properly sized string influence the annual yield far more.

Installation: under five kilograms and passive cooling

The 280 by 310 by 184 mm housing weighs just 4.8 kg and can be mounted by one person, which is among the reasons installers like this series: no helper and no lifting gear are required. Cooling is natural with no fan and noise does not exceed 35 dB, so the inverter can sit in a hallway, a stairwell or a utility cupboard without becoming a nuisance. IP65 protection and tolerance of humidity up to 100 % non-condensing allow mounting on an external wall under a canopy, often the simplest answer on a small site. The operating range runs from -25 to +65 °C with derating above +45 °C: the upper limit is generous, but direct midday sun on the housing will still cost part of the yield, so a north-facing or shaded wall is preferable. Panels connect through MC4 connectors, the AC side through an IP65 connector, and the DC isolator is integrated, so no separate DC box is needed.

Protection, certification and monitoring

The protection set covers earth-fault monitoring, grid parameter monitoring, DC reverse-polarity protection, short-circuit protection and type II surge arresters on both the DC and the AC side. The topology is transformerless, which is where the high efficiency and low weight come from — and precisely why proper earthing and a correctly built surge protection scheme matter here. Certification spans IEC/EN 62109-1/2, IEC 61727, IEC 62116, VDE4105, VDE0126, AS4777.2 and CEI 0-21: that list is needed not for show but for approval by the network operator if you intend to export surplus. Monitoring runs over RS485, RS232, Wi-Fi or LAN, there is a simple LCD 1602 text display on the housing, and daily curves are read in the mobile app. The manufacturer warranty is five years; for a grid-tie inverter that never works with a battery this is a reasonable term, because the load on its power stage is even and predictable.

How it differs from its neighbours in this catalogue

Within the same series the only differences are power and tracker count: the SUN-2K-G (item 2085) shares this housing and single MPPT but delivers 2 kW with an array limit of 2.6 kW, while the SUN-3.6K-G (item 2084) gives 3.6 kW and up to 4.7 kW of panels in the same 4.8 kg case. If more than 4 kW of panels or two different roof planes are planned, the SUN-5K-G (item 2086) makes more sense with its two independent trackers and a 6.5 kW array limit. For a large site the series offers the SUN-10K-G (item 2068) with two 26 A MPPTs, an array of up to 13 kW and 45.5 A of output current, though that already requires a 50 A circuit. A fundamentally different choice is a hybrid: the SUN-3K-SG04LP1-EU (item 2048) at the same rating works with a battery and keeps the power on during outages, but the system around it costs more and is more complex. So choosing between 2083 and 2048 is not a question of kilowatts but of what you need: a smaller bill, or lights in the house when the grid is down.

Tell us how many panels you plan to install and whether you need power during outages, and we will say whether a grid-tie inverter fits or a hybrid is the better buy.