About the Number of Bays Estimator

Number of bays calculation determines how many circuit bays are required in a solar plant's HT switchyard — one bay per electrical feeder, plus bus-section and transformer bays — which drives the switchyard's physical size, equipment cost, and land requirement.

How to calculate it

1. 1Minimum bays for a single-bus scheme: one incoming feeder bay + one outgoing (transformer) bay = 2 bays. Add a bus section bay if splitting the bus for reliability.
2. 2For plants with multiple transformers or multiple grid connections: one bay per transformer + one bay per feeder + bus section bays as needed.
3. 3Double bus scheme (for critical plants): doubles the number of bus-connected bays but allows maintenance on one bus section without total shutdown.
4. 4BESS integration: if the BESS has its own HT connection (separate from the solar PV), add one bay per BESS PCS transformer.
5. 5Future bays: add foundation provisions for 1–2 future bays during initial construction (minimal cost vs full future excavation).

Worked example

A 10 MWp solar plant at 33 kV: two 5 MVA step-up transformers (2 transformer bays) + one grid incoming feeder (1 feeder bay) + one bus section bay = 4 bays total for a single-bus scheme. Adding a 5 MWh BESS with separate HT connection: +1 BESS transformer bay = 5 bays total. Switchyard area: 5 × 80 m² per bay = 400 m² + control room 30 m² + access = ~500 m² total.

What you can calculate

• Feeder bays
• Transformer bays
• Expansion reserve
• Bay count

Frequently asked questions