Hotel Power Design: Where Storage Belongs on the Single-Line Diagram

Start with the hotel's daily curve

A hotel is never one load. Guest rooms follow check-in and the evening peak, kitchens and laundry start before dawn, the chiller plant climbs with afternoon temperature, and a banquet adds a step change the moment an event begins. The fifteen-minute curve shows where those peaks stack; the monthly kWh bill does not.

Two hotels with the same room count can differ by a factor of two in required discharge power once hot water and laundry are counted. That is why the first document we ask for is interval data, not the bill.

Fix the connection point on the single-line diagram

Storage is usually coupled on the low-voltage side of the main distribution board, behind the utility metering and ahead of the transfer to the standby generator. The diagram must show the transformer spare capacity, the prospective fault level at that board, and whether the generator can carry essential loads with storage isolated.

Where two transformers run in parallel, the point of common coupling and the protection settings decide whether the system may export. These are drawing questions before they are equipment questions, which is why hotel projects start from the single-line diagram rather than from a cabinet datasheet.

The four inputs we ask for

Interval load data for at least four weeks, the tariff structure including demand charges, the PV generation profile if an array already exists, and the plant-room space available for cabinets with the fire separation the local code requires.

Where the numbers usually land

For hotel retrofits we most often see two to four hours of storage relative to peak load, set by the tariff window and by how long the site needs to ride through a supply interruption. In hot plant rooms a larger derating margin is needed and cooling must be verified at commissioning.