Deye SUN-20K-G04 (20 kW) - three-phase grid-tie inverter

Twenty kilowatts and six strings: the model's main strength

The SUN-20K-G04 has two independent MPPTs, each accepting three strings — six in total, the greatest layout flexibility among grid-tie models of this class. In practice that rescues sites where panels will not fit into two even rows: a roof with dormer windows and chimneys, two slopes plus a canopy, an extension at a different pitch, part of the array on the ground. Operating current is 32 A per tracker with short-circuit current up to 48 A, so three strings of modern modules can be paralleled on one input without exceeding the limit. The array may reach 26 kW against the 20 kW rating — the standard 30 % oversizing that delivers real output in November and January. The model's main limitation is the one shared by the whole G series: it supports no battery and does not operate during an outage, so backup cannot be had from it.

Twenty-three kilograms: why a grid-tie unit is three times lighter

The 362 by 577 by 215 mm housing weighs 23 kg — a third of a hybrid at the same rating (the SUN-20K-SG05LP3-EU-SM2, item 2056, weighs 51.9 kg). The reason is simple: a grid-tie inverter has no battery converter, no chokes for large 48 V currents and a smaller heatsink, because there is less loss to dissipate. For the site that means cheaper installation: two people, ordinary anchors, no frames and no hoists. Cooling is intelligent and typical noise reaches 40 dB — noticeably quieter than the hybrids — so the inverter sits comfortably in the utility room of an office or a shop. The operating range is -25 to +65 °C with derating above +45 °C, protection is IP65, mounting is on the wall and the input uses MC4 connectors.

98.6 % efficiency and the honest arithmetic of losses

Maximum efficiency is 98.6 % with a European figure of 97.8 %, noticeably higher than any hybrid can offer (97.6 % at best). At twenty kilowatts one percentage point means 200 W of constant loss, around 300 kWh a year given up to conversion alone. Tracking efficiency exceeds 99 %, output distortion stays below 3 % and night-time self-consumption is under a watt. The MPPT window is 200 to 850 V with a 1000 V maximum and start-up from 250 V: strings of fourteen to twenty modules work comfortably in range, and the high voltage reduces losses in the cable from roof to inverter. The practical conclusion for a commercial site: if backup during outages is not required, a grid-tie inverter will harvest more energy from the same array than a hybrid.

30.3 A per phase at the output: connection and paperwork

Rated output current is 30.3 A per phase at 220 V and 29 A at 230 V with a maximum of 33.3 A: the inverter connects in parallel with the service through its own 40 A per phase breaker using 10 mm² cable. Apparent power is 22 kW, grid voltage 3L/N/PE 220/380 or 230/400 V and frequency 50/60 Hz. An official connection requires a bidirectional meter and operator approval: certification covers IEC/EN 62109-1/2, IEC 61727, IEC 62116, EN 50549 and VDE4105, the full set of documents an operator asks for. Anti-islanding protection to IEC 62116 disconnects the inverter within a fraction of a second when the grid fails — which is precisely why no backup is possible from it. The remaining protections: earth-fault monitoring, grid monitoring, DC reverse-polarity protection, type II surge arresters on both sides and an integrated DC isolator.

What monitoring reveals across six strings

Communication through RS485, RS232, Wi-Fi and LAN is built in, with no separate modules to buy; control comes from the display on the housing and the mobile app. Six strings mean six potential places for a fault, and this is where per-tracker monitoring turns from a convenience into a tool: a string sagging because of shading, soiling or a failed module shows up in the daily curves. For a commercial site with its own maintenance team, access over LAN or RS485 allows the data to be fed into the company's metering system. The event log retains fault codes, which shortens diagnosis when a service call is made. Maintenance of the inverter itself amounts to checking terminals and keeping the heatsink clean; apart from the fan it contains no moving parts.

The sites where this rating is optimal

Twenty kilowatts of generation suits a site consuming 60 to 100 kWh during the day: a mid-sized supermarket, a single-shift production hall, an air-conditioned office building, a hotel, a greenhouse operation, a dairy farm. A 26 kW array is roughly 45 to 50 modules of 550 W and 110 to 130 m² of surface — a workshop or warehouse roof, or a large canopy. The economics are best where consumption falls in daylight hours: manufacturing, retail, offices with air conditioning. For a site that operates at night the grid-tie inverter will export the surplus at the sale rate and the payback period lengthens. And if continuity is critical — cold rooms, servers, process equipment — a hybrid is required, and the SUN-20K-SG05LP3-EU-SM2 (item 2056) or SUN-20K-SG01HP3-EU-AM2 (item 2070) deserve a look.

How it differs from its neighbours in this catalogue

The smaller SUN-15K-G03 (item 2073) has two trackers at 13 and 26 A with three strings in total, a 19.5 kW array and a mass of only 15 kg — simpler to install but less flexible in panel layout. The SUN-25K-G05 (item 2049) delivers 25 kW with two 26 A trackers (four strings), a 32.5 kW array and 20 kg of mass. The larger SUN-30K-G04 (item 2051) offers 30 kW, 40 A trackers and a 39 kW array, but weighs 44.5 kg with noise up to 50 dB. If the panels are scattered across many surfaces, this model's six strings remain a solid argument even against higher-rated units. And if power during a blackout is needed, the G series should be ruled out entirely in favour of LP3, SM2 or HP3 hybrids.

Can storage be added later

The question comes up almost every time: the system was installed to cut costs, and then the outages began. There is no direct yes here — a grid-tie inverter has no battery input, and nothing can be grown onto it. But there is a working way around: a hybrid inverter is installed in parallel on the AC side, working with the battery while the SUN-20K-G04 keeps harvesting from the panels. That arrangement is called AC coupling; it requires the priorities of the two devices to be reconciled and is less efficient than a hybrid system designed as one from the start, yet it preserves the money already spent. If outages are already critical for your site, however, it is sounder to buy a hybrid from the outset and keep grid-tie units for places where only the economics matter.

Send us a roof plan with the orientation of each surface and we will advise whether this model's six strings suffice or a higher rating is worth taking.