160 kVA 11 kV Oil-Immersed Step-Up Transformer for Solar PV & Wind Power Stations – Grid-Tied / Off-Grid, IEC 60076

Model:S22-M-160/11 (S20-M-160/11 and S13-M-160/11 optional)

Rated Capacity:160 kVA

Phase:Three-phase

Frequency:50 Hz / 60 Hz

Rated High Voltage (HV):11 kV (10, 12, 13.8, 20, 22, 24, 33, 35 kV optional)

HV Tapping Range:±2×2.5% off-circuit (±5% optional, OLTC on request)

Rated Low Voltage (LV) :0.4 kV (0.415, 0.48, 0.69, 0.8 kV optional)

Direction of Use: Step-up (0.4 → 11 kV) and step-down (11 → 0.4 kV) in the same unit

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160kVA Oil-Immersed Transformer

Quick Answer

A 160 kVA 11 kV oil-immersed transformer for a small photovoltaic or wind station is a hermetically sealed three-phase unit that steps the inverter or turbine output up from 0.4 kV — or 0.69 kV on wind — to 11 kV for the grid connection, and steps 11 kV back down to 400/230 V when the same site runs in off-grid island mode. Solar and wind duty is dominated by no-load loss rather than load loss: the transformer stays energised 8,760 hours a year while a PV array only produces at a 12–20% capacity factor, so no-load loss accounts for roughly 60% of the annual energy lost. Specify a low no-load-loss design (S22, GB 20052-2024 Class 1), Dyn11 vector group and a sealed corrugated tank.

Product Overview

This is a three-phase, 50/60 Hz oil-immersed transformer rated 160 kVA with an 11 kV winding and a 0.4 kV winding, used in either direction: as a step-up transformer feeding 11 kV from the inverter or turbine side, or as a step-down transformer serving 400/230 V loads when the site runs as an island. Both windings are copper. The active part is sealed inside a corrugated-fin steel tank with no conservator, so the insulating oil never contacts air and never needs sampling, filtration or topping-up over a 25-year design life.

It is built for small renewable sites: ground-mount and rooftop PV up to roughly 150–200 kWp, single medium wind turbines and small wind clusters, PV-plus-battery mini-grids, hybrid solar–diesel systems for villages, farms, ranches and telecom sites, and off-grid loads such as irrigation pumping and water treatment. The standard supply includes oil temperature monitoring with alarm and trip contacts and an RS485/Modbus RTU interface, with an optional 4G or LoRa DTU so the plant SCADA or a cloud dashboard can read oil and winding temperature, load current and voltage. Designed and tested to IEC 60076-1/-2/-3/-5/-10, with wind-turbine applications additionally designed to IEC 60076-16; energy performance per GB 20052-2024; manufactured under ISO 9001, ISO 14001 and ISO 45001.

Why Solar and Wind Sites Choose Sealed Oil-Immersed Over Dry Type

Our recommendation: for an outdoor PV array, wind cluster or hybrid mini-grid, specify a hermetically sealed oil-immersed transformer. Reserve cast resin dry type for indoor electrical rooms, high-altitude plateau sites above roughly 3,000 m, and any location where the fire or environmental code rules out mineral oil.

The reason is the duty cycle. Renewable output is intermittent — PV swings with cloud transients, wind with gusts — and oil has far greater thermal mass than air, so the tank absorbs each peak without driving the winding hot spot up. The sealed tank also removes two failure modes specific to renewable sites: night-time condensation when the LV side is open and the tank cools, and the periodic oil maintenance that remote sites are least able to perform.

Consideration	Sealed Oil-Immersed (this product)	Cast Resin Dry Type	Impact on a PV / wind site
Night-time idle	No-load loss 170 W (S22); sealed tank blocks moist air as it cools	Higher no-load loss; open windings collect dew and dust	Sealed oil removes both the idle loss and the condensation risk
Intermittent load	Oil thermal mass smooths cloud transients and gust peaks	Lower thermal mass, faster hot-spot rise	Oil suits PV and wind duty cycles
Outdoor installation	IP54 cable boxes, outdoor compound, bunded	Needs a room or enclosure	Oil wins open-field sites
Fire and environment	Combustible oil; ester option or bund where required	Self-extinguishing, no oil	Near forest or water, choose dry type or ester oil
Cost per kVA	Lowest	Typically 10–15% higher	Oil suits capex-sensitive small projects
Altitude	Derating or special design above 1,000 m	Handles altitude better	Dry type for plateau sites above 3,000 m
Noise	≤ 55 dB(A), low-noise build ≤ 50 dB(A)	Slightly quieter	Rarely decisive on remote renewable sites

Energy Efficiency Grades and the 20-Year Running Cost

On a renewable site the transformer is energised far longer than the plant produces. A PV array runs at a 12–20% capacity factor, yet the transformer sits on 11 kV for all 8,760 hours of the year, including every night. That is why the no-load figure, not the purchase price, decides the 20-year cost — and why the grade you specify matters more here than on a conventionally loaded distribution transformer.

GB 20052-2024 Grade	Model	No-load loss P0	Load loss Pk (75 °C)	Annual loss – PV duty	Annual loss – wind duty	20-yr cost – PV	20-yr cost – wind
Class 3	S13-M-160/11	200 W	2,310 W	≈ 2,780 kWh	≈ 4,034 kWh	≈ USD 6,672	≈ USD 9,682
Class 2	S20-M-160/11	180 W	1,850 W	≈ 2,400 kWh	≈ 3,405 kWh	≈ USD 5,760	≈ USD 8,172
Class 1	S22-M-160/11	170 W	1,650 W	≈ 2,223 kWh	≈ 3,119 kWh	≈ USD 5,335	≈ USD 7,486

Moving from Class 3 to Class 1 saves about 11,140 kWh over 20 years on a PV site and about 18,300 kWh on a wind site — at USD 0.12/kWh that is roughly USD 1,340 and USD 2,200 respectively, usually several times the price difference between the two designs. Note the split: on PV duty the no-load loss alone accounts for about 63% of the annual total, so a design that only improves load loss is the wrong choice for this application.

Grid-Connected vs Off-Grid: What Changes

The transformer itself is bidirectional and needs no change between the two modes. What changes is the earthing, the protection scheme and, on weak feeders, the tapping range.

Item	Grid-connected (grid-tied)	Off-grid / island
Power flow	0.4 kV → 11 kV, export to the utility	Both directions: 0.4 → 11 kV by day, 11 → 0.4 kV for site loads
Neutral and earthing	As the utility requires	LV neutral must be earthed (TN-S or TT) — Dyn11 provides it
Tapping range	±2×2.5% normally sufficient	Wider range or OLTC if island voltage swings
Voltage rise	Long feeders may need ±5% or OLTC	Not applicable
Short-circuit level	Utility contributes fault current	Inverters only — low; Uk% affects protection sensitivity
Night behaviour	Idle, no-load loss only	May be switched off with the island
Protection	Utility interconnect and anti-islanding	Island protection; no anti-islanding requirement

Key Features

Dual-direction by design — 0.4 kV to 11 kV step-up for grid export, 11 kV to 0.4 kV step-down for island loads. One unit covers both operating modes of a hybrid solar, wind and battery site.
Low no-load loss tuned for renewable duty — the S22 design is 170 W against 200 W for Class 3. On PV duty no-load loss is about 63% of the annual total because the unit is energised 8,760 h while the array produces at a 12–20% capacity factor.
Sealed corrugated tank — no conservator, the oil never contacts air. No oil sampling, filtration or topping-up for the 25-year design life, and no moist air drawn in when the tank cools overnight with the LV side open.
Built for intermittent duty — oil thermal mass smooths cloud transients on PV arrays and gust peaks on wind turbines without driving the winding hot spot up.
Designed for inverter and converter waveforms — winding design accounts for aggregate inverter harmonic current per IEEE 519 / IEC 61000-3-12 and IEEE C57.110, and for DC current injection, which biases the core and raises magnetising current, noise and no-load loss if it is not addressed.

Typical Applications

Ground-mount and rooftop PV plants up to roughly 150–200 kWp feeding an 11 kV feeder
Single medium wind turbines and small wind clusters with 690 V generator output
Hybrid PV + battery + diesel mini-grids for villages, farms, ranches and telecom sites
Off-grid islands, mining camps, water pumping and irrigation stations
Commercial and industrial rooftop solar with 11 kV export
Solar-plus-storage microgrids and remote electrification projects
Agricultural and desalination renewable sites in desert and coastal climates

Standards and Certifications

Designed and tested in accordance with IEC 60076-1 (general), IEC 60076-2 (temperature rise), IEC 60076-3 (insulation levels and dielectric tests), IEC 60076-5 (short-circuit withstand), IEC 60076-10 (sound level) and IEC 60076-16 (wind turbine transformer applications), plus GB 1094 series and GB/T 6451. Energy performance meets GB 20052-2024 Class 2 as standard and Class 1 with the S22 design. Inverter and converter harmonic duty designed with reference to IEEE C57.110, IEEE 519 and IEC 61000-3-12. Manufactured under ISO 9001, ISO 14001 and ISO 45001. CE conformity available; third-party type test reports (CNAS-accredited laboratory, KEMA or equivalent) available on request.

Q1: What size transformer do I need for a 150 kW solar PV system?

Match the transformer to the inverter AC output, not the DC array size. A 150 kWp array is normally paired with 120–150 kW of inverter capacity, because modules rarely reach nameplate and the DC side is often oversized by 1.1–1.2. A 160 kVA transformer covers that with margin for reactive power and future expansion. Rule of thumb: transformer kVA ≈ inverter AC kW ÷ 0.9, then round up to the next standard rating.

Q2: Can the same transformer be used for grid-connected and off-grid operation?

Yes — a transformer is bidirectional, and this unit is specified for both directions. In grid-tied mode it steps inverter output up from 0.4 kV to 11 kV for export; in island mode it steps the 11 kV mini-grid down to 400/230 V for site loads. What changes between the two modes is not the transformer but the earthing and protection: the LV neutral must be earthed (TN-S or TT) in island mode, and anti-islanding protection is required only in grid-tied mode.

Q3: Why does no-load loss matter more than load loss on a solar transformer?

Because the transformer is energised far longer than the plant produces. A PV array runs at a 12–20% capacity factor, yet the transformer sits on 11 kV for all 8,760 hours of the year, including every night. On a 160 kVA unit, no-load loss contributes about 63% of annual losses on PV duty and about 43% on wind duty. That is why the S22 Class 1 design at 170 W matters more here than it would on a conventionally loaded distribution transformer.

Q4: What voltage does a 160 kVA solar transformer step up to?

On this unit, 0.4 kV to 11 kV as standard. 11 kV is the common distribution voltage across the UK, much of Asia, Africa, the Middle East and Australia; 10 kV is standard in China and 13.8 kV in parts of the Americas. The HV winding is configurable from 10 kV to 24 kV, with 33 kV and 35 kV for longer feeders. Wind configurations typically use 0.69 kV on the LV side.

Q5: Can the LV side be 0.69 kV for a wind turbine?

Yes. 690 V is the standard generator output of most medium wind turbines, and this transformer is supplied with a 0.69 kV LV winding for turbine duty. For 1500 V PV systems the LV winding is 0.8 kV. Voltage ratio, vector group, tapping range and frequency are all configurable at order.

Q6: Do solar inverters damage the transformer through harmonics?

Modern inverters stay within IEEE 519 and IEC 61000-3-12 limits, with THDi typically below 3–5%, so harmonic heating is far less severe than on DC fast-charging sites. Two inverter-related effects still need to be addressed at specification: DC current injection, which biases the core and raises magnetising current, audible noise and no-load loss; and the aggregate harmonic current of many inverters on one transformer, which we account for in the winding design per IEEE C57.110.

Q7: Does a PV transformer need an on-load tap changer?

Usually not. Off-circuit taps of ±2×2.5% cover normal grid variation. An OLTC or a wider ±5% range is worth paying for when the plant connects to a weak rural feeder, because exporting power raises the voltage at the point of connection and a long feeder can push it beyond limits at midday. Ask the utility for the fault level and the voltage rise study before deciding.

Q8: What happens to the transformer at night when the inverters stop?

It stays energised on the 11 kV side and draws only no-load loss — about 170 W for the S22 design, roughly 1,490 kWh a year. Two design details matter here: the sealed tank prevents moisture-laden air from being drawn in as the tank cools overnight, which is the usual cause of insulation degradation on renewable sites; and if the owner wants to remove the night loss entirely, the HV side can be switched out, which we can accommodate in the protection scheme.

Q9: Can an oil-immersed transformer be installed in a solar or wind farm?

Yes, and it is the usual choice for outdoor renewable sites because it costs less per kVA and handles intermittent load better than dry type. Local rules typically require a bund, spill containment or a suitable setback, and some authorities restrict mineral oil near forests, water catchments or protected land — for those sites the natural ester option provides a biodegradable, higher fire-point alternative.

Q10: Is it suitable for desert heat, high altitude or coastal sites?

Standard design covers -25 °C to +40 °C ambient and up to 1,000 m altitude. Above 1,000 m the thinner air reduces cooling capacity, so a high-altitude design or a derated rating is required — common for plateau PV above 3,000 m. Desert sites typically need a +50 °C ambient rating and C5-M corrosion protection; coastal and offshore-adjacent wind sites need C5-M coating and upgraded cable box sealing.

Q11: Should I choose natural ester oil instead of mineral oil?

Choose ester where the site is environmentally sensitive or fire-restricted: it is readily biodegradable, its fire point is above 300 °C against roughly 160 °C for mineral oil, and it absorbs moisture, which slows paper ageing and can extend insulation life. The trade-offs are higher first cost, higher viscosity (accounted for in the cooling design) and the need to confirm the utility accepts it. For a standard open-field PV or wind site, mineral oil remains the value choice.

Q12: What is the delivery time and how is the unit packed?

Production is typically 3–6 weeks depending on voltage class, loss grade and order quantity. Units ship oil-filled and factory-sealed on a steel-reinforced wooden pallet, wrapped in moisture-barrier film with desiccant, HV and LV bushings plus cable boxes guarded by plywood, fitted with lifting lugs and shock/tilt indicators. Full export plywood crating is available; where destination regulations require it, the unit can ship drained with oil in sealed drums. Final gross weight, crate dimensions and packing list confirmed before shipment.

Shipped oil-filled and factory-sealed on a steel-reinforced wooden pallet, wrapped in moisture-barrier film with desiccant, HV and LV bushings plus cable boxes protected by plywood guards, fitted with lifting lugs and shock/tilt indicators. Suitable for sea, road and rail transport; full export plywood crate available on request. Where destination regulations require, the unit can be shipped drained with oil in sealed drums. Final gross weight, crate dimensions and packing list confirmed before shipment.