The Ambala depot has a 120 kWp grid-tied solar plant on the dry store roof. It feeds the depot's own load; it shuts down when the grid fails and is never counted on in an outage.
The depot sits beside the highway and a lime kiln, and dust settles quickly. The panels are washed every seven days all year, with plain tap water and soft mops, early in the morning before the glass heats up. Nobody uses detergent, a brush with hard bristles, or a pressure washer.
The weekly yield report shows how much is being lost to soiling; if it shows a sudden drop, wash the next morning instead of waiting for the weekly turn.
The single inverter is checked once a quarter by the solar contractor, who downloads its alarm history and sends a short report to the regional engineer. Between visits, the depot's technician looks at its display each Monday and phones the contractor if it shows a fault.
Nobody walks on the panels. The roof is reached only by the fixed ladder with its cage, by people who have been trained and who are wearing the roof kit kept in the technician's store. The roof is closed in rain, in strong wind and after dark.
Two people go up together, always.