Inverter substation for an industrial solar plant: 10 kV switchgear, transformer and inverter hall in one block

The task

The solar plant needed a substation that combines three functionally different zones in a single unit:

• the inverter hall — equipment that generates heat, needs cooling and regular access;
• the power transformer — oil-filled, with its own containment requirements;
• the 10 kV switchgear — a high-voltage zone with restricted access.

You cannot simply place these three side by side: they have different climate, access and fire-safety requirements. On top of that came a commercial condition — a certificate of origin (form U-1), without which the plant would not qualify for its feed-in tariff premium.

The solution

We used a segregated layout within one block: 10 kV switchgear, transformer compartment and inverter hall as separate zones, each with its own doors and its own conditions.

Inverter hall.
Per the passport, each substation holds 8 inverters of 100 kW. Built into the structure:

• embedded fixings for the inverter mounting frames, dimensioned for their weight;
• PV cable entry through a dedicated floor opening beneath each inverter, plus a spare; then along the walls in galvanised trays;
• circuit-breaker extension bars for cables of 95–240 mm²;
• dedicated earthing points for the inverters — 35 mm² copper — and from 6 mm² for the trays.

Climate and safety. Air conditioning with at least 8 kW of cooling capacity, working and emergency lighting, fire detection, and an auxiliary supply board. The roof is insulated with at least 100 mm of non-combustible material — supplied with its non-combustibility certificate.

Transformer compartment. Oil containment sump and collector sized to hold the required oil volume per the electrical installation code — shown on the frame drawing.

10 kV switchgear. Cells rated IP54, with sealable cable entries and exits. The working current was taken with a 20% margin. The 10 kV busbars are aluminium; internal wiring is copper.

Telecontrol readiness. The protection scheme includes a telecontrol terminal block with breaker position contacts and provision for remote-control contacts on the vacuum circuit breaker. Space is also allowed for a class A power quality analyser with telemetry readout, coordinated with the telecontrol contractor and the DSO's requirements.

Installation documentation. Delivered with the unit: the frame structure in DWG (so the client could design the foundation), a dimensional drawing with the inverter layout, protection schematics and specifications.

The series product card: concrete packaged transformer substation (БКТП). For designers: the typical solutions "1000 kVA substation for solar plants" and "package substation for solar plants". We also build the plants themselves: turnkey industrial solar plants.

Figures (from the passports)

КТП-1000/10/0.4 У1 packaged inverter transformer substation

Serial Nos. 172936, 172937, 172938, 172939 · passport Э-21-311 ПС · Odesa, 2021

Bill of supply per substation (from section 4 of the passport)

🔢 Order totals: 4 substations × 1000 kVA = 4000 kVA; 4 × 8 = 32 inverters of 100 kW, i.e. 3.2 MW of inverter capacity. Plus 12 КСО-Е cells and 12 ЩО-90 panels — all of our own manufacture.

From the order requirements (parameters the passport does not cover): cell ingress protection IP54 · +20% working current margin · roof insulation at least 100 mm of certified non-combustible material · air conditioning with at least 8 kW cooling capacity · oil sump and collector per the installation code · aluminium 10 kV busbars, copper internal wiring · PV cables 95–240 mm² · earthing 35 mm² for inverters, from 6 mm² for trays · RAL 7040 finish · service life at least 25 years, warranty at least 24 months · certificate of origin form U-1 (for the feed-in tariff premium).

Why this is harder than a standard package substation

A standard transformer substation has two zones: high voltage and low voltage. Here there are three, and the third one plays by different rules: inverters generate heat, so they need cooling; they are serviced more often, so access has to be convenient; a dozen large-section power cables run to them, so entries are designed per device. Packing all of that into one transportable block is a separate engineering job — and it is solved at the design stage, not during installation.

One more thing the passport shows. Inside the substation sits our own equipment: three 10 kV КСО-Е cells and three 0.4 kV ЩО-90 panels (one at 2000 A and two at 1000 A), plus the auxiliary supply board. The station is not assembled from other people's subsystems — it is built from products of the same plant, from the 10 kV cell to the 0.4 kV panel and the enclosure itself.

Photo report: finished blocks before shipment

We'll cost an inverter substation for your solar plant

Send us the number and model of inverters, the transformer rating and your DSO's requirements — we'll build the block with switchgear, transformer compartment and inverter hall, complete with climate control, fire detection and telecontrol readiness.