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A solar inverter & step-up transformer integrated unit for utility PV puts the inverter, the step-up transformer and the high voltage switching on one skid inside a container cabin. Direct current from the arrays arrives at the inverter at a low DC voltage and leaves the unit at the collection voltage, so no long low voltage cable run crosses the site. It suits utility-scale solar farms that want fewer foundations, fewer cable trenches and a shorter commissioning programme.
The container enclosure of the solar inverter & step-up transformer integrated unit for utility PV is built to IP54 with weather-resistant seals and dust screens, while the inverter compartment takes independent air ducting and the transformer stays on ONAN cooling. CRGO Hi-B core steel and electrolytic copper windings sit in an oil-paper insulation system inside a fully sealed tank, and an integrated copper busbar links inverter to transformer with no cable joint. Monitoring for the renewable plant is commissioned from one interface.
| Electrical & Standards | Rated output power | 2500-4400 kW reference class; higher ratings engineered to order |
Voltage combination (HV-LV) | 1500 Vdc strings -> AC 10-35 kV (example 35 kV / 0.63 kV); HV selectable per grid | |
Vector group | Dy11 common; others per grid & earthing requirements | |
Tapping | Off-circuit taps per transformer design | |
Rated frequency | 50 Hz standard; 60 Hz for export, engineered to order | |
Efficiency & power quality | Peak inverter efficiency up to ~99% class; current THD < 3%; power factor adjustable 0.8 lead - 0.8 lag | |
Cooling | Transformer ONAN; inverter forced air with independent ducting | |
Protection / IP & environment | Enclosure IP54 (inverter IP55/IP65); -35 to +60 degC with derating above +40 degC; operation up to 5000 m altitude | |
Standards & certification | GB、CE、IECEE CB、KEMA、ISO; IEC 60076 / IEC 62271-202; inverter grid codes | |
| Structure & Materials | Enclosure & shell | Steel container / prefabricated cabin; IP54 typical; weather-resistant seals, heater / dehumidifier, dust screens |
Compartment layout | Inverter power section, step-up transformer and HV switching on one skid, or container rooms; modular independent power sections | |
Core | CRGO Hi-B silicon steel | |
Windings | Electrolytic copper; foil on high-current side | |
Insulation system | Oil-paper composite (oil-immersed transformer), PCB-free | |
Insulating oil | Mineral oil standard; ester oil option for eco / fire-safety projects | |
Transformer tank | Fully sealed type | |
Bushings & terminations | Integrated copper busbar / busway between inverter and transformer - no long LV cable run | |
Corrosion / coating | Corrosion coating C3 standard; C4/C5 optional | |
Mounting & base | Skid / container base, forklift- and crane-liftable; foundation fixing per drawing |
The core is built from CRGO Hi-B silicon steel with fully mitered joints, which keeps no-load loss and sound level down over the long operating hours of a generation asset. An amorphous metal core is available on request where no-load loss is the deciding factor.
On the inverter side the winding carries a high current at a low voltage, so the low voltage winding is produced as electrolytic copper foil. Foil construction gives a uniform current distribution, a low stray loss and a good withstand against the harmonic currents that inverter duty imposes.
The high voltage winding is wound from electrolytic copper wire and insulated for a system voltage of 10 kV or 35 kV, with an aluminium winding offered as an option where the project specifies it.
Oil-immersed units use an oil-paper composite insulation system with PCB-free mineral oil, and ester oil where the project is environmentally sensitive. Where oil is not acceptable, the transformer is supplied as a dry-type unit with epoxy cast-resin insulation.
The tank is fabricated from Q235 corrugated or plain plate and is fully sealed, with no conservator. Cooling is by oil circulation to the tank walls and radiators for oil-immersed units, or by air for dry-type units, with forced cooling applied where the rating requires it.
The enclosure is a double-layer sandwich construction in steel or composite board with a fireproof thermal-insulation filling and a rain-shed roof. Natural ventilation is combined with forced ventilation so that heat is rejected from the transformer room under full load.
The high voltage and low voltage rooms are fully separated, and the transformer is mounted externally or semi-externally so that its heat does not load the switchgear rooms. Door interlocks prevent access to a live compartment in service.
Porcelain or composite bushings are fitted for the high voltage connections, and the cables enter from below through a bottom entry with cable seals, which suits the buried cable practice used on most PV and wind sites.
Vector group Dyn11 is the common connection, with Ynd11 applied where the grid and earthing arrangement calls for it; the delta low voltage winding suppresses third harmonic currents. Off-circuit taps of plus or minus 2 x 2.5 percent are standard, and an on-load tap changer can be specified where the grid voltage moves during the day.
Base lifting lugs allow the complete unit to be lifted in one piece onto its foundation, and the footprint follows the factory datasheet. For coastal or offshore sites a C4 or C5 anti-corrosion coating system, silicone seals, anti-condensation heating and rodent-proof mesh are applied.
Every renewable energy transformer is routine tested as a transformer and, where the scope includes the enclosure and switchgear, function tested as a complete assembly before shipment.
Core steel, foil and wire conductor, tank plate and insulating oil are inspected against the approved specification on receipt, and traceability records are kept for every batch used in the active part.
Winding, core stacking, tanking and oil filling are checked stage by stage, so that every Solar Inverter & Step-Up Transformer Integrated Unit for Utility PV is verified against its design before it moves to final testing.
Routine testing follows IEC 60076 and covers winding resistance, ratio and vector group, no-load and load loss, impedance, insulation resistance, applied and induced voltage withstand, and oil tightness on sealed units. Where the supply includes the enclosure, the assembly is checked to IEC 62271-202 practice and against the applicable PV or wind grid-code requirements.
The unit is shipped with a routine test report and a certificate of conformity, recording the measured values against the nameplate data.
Solar Inverter & Step-Up Transformer Integrated Unit for Utility PV is configured around the generation asset it serves: the inverter or turbine output voltage, the collection network voltage and the grid connection requirements come first, and the transformer, enclosure and protection follow from them.
Capacity is built from 1000 kVA to 3150 kVA and above, with higher ratings engineered for larger blocks. The high voltage side is normally 10 kV or 35 kV, and the low voltage side follows the inverter, typically 0.27 kV, 0.315 kV, 0.4 kV or 0.8 kV, with 0.8 kV used for large central inverters.
Cooling is oil-immersed ONAN or ONAF, or dry-type AN or AF where no oil is permitted. Insulation is oil-paper composite with mineral oil, or ester oil for environmentally sensitive projects; vector group Dyn11 or Ynd11, off-circuit taps or an on-load tap changer, CRGO Hi-B or amorphous core, and aluminium windings are all selectable.
For the enclosure and site conditions, the double-layer shell, compartment layout and C4 or C5 anti-corrosion coating are matched to the location, with silicone seals, anti-condensation heating and rodent-proof mesh for humid, coastal or desert sites.
Renewable energy transformers are packed for long-distance transport to generation sites, which are often remote and have limited handling equipment on arrival.
Secure Packaging: Bushings, accessories and control cabinets are protected and braced against vibration and impact, and openings are sealed against moisture and dust.
One-piece Lifting: Base lifting lugs allow the complete assembly to be lifted in one piece, so no reassembly is needed at the site.
Reliable Transport: Road, rail or sea freight is arranged to the project schedule, with the route and handling method agreed for oversized units.
Complete Documentation: Routine test report, certificate of conformity, drawings, manuals and shipping documents travel with the unit.
Installation Support: Guidance on foundation, cable entry, earthing, protection settings and energisation is available through commissioning.
The degree of protection, the tank or enclosure construction and the coating system are matched to the site conditions.
Inverter-fed and turbine-fed plants impose harmonic currents and load swings on the transformer, and the design accounts for that duty rather than treating the unit as a plain distribution transformer.
It is the transformer that raises the output of a generating asset to the voltage of the collection or export network. Instead of connecting each inverter, turbine or storage unit to the grid separately, the plant is collected into one or more step-up points with their own protection, switching and metering.
