Yinchuan Depot — Modeling Solar and Storage Together at a Single-Depot Scale

The Problem

Not every transit depot is a mega-facility. Yinchuan's 45-bus depot represents the far more common case: a mid-sized transit operator asking whether investing in solar PV and a modest on-site battery is worth it at a scale smaller than the flagship 100+ bus projects that dominate the industry conversation.

The question isn't just "will it fit" — it's "does adding solar and storage to a compact depot actually move the needle on grid dependence, or is it a rounding error?" For a mid-sized operator with a tighter capital budget than a major metro authority, that answer determines whether the project gets funded at all.

How the Depot Digital Twin Was Used

Step 1 — Model the depot with its generation and storage assets together. The 45-bus fleet was built against the depot's real electrical service, with both a solar PV array and a battery energy storage system (BESS) modeled as first-class assets in the site's electrical topology — not bolted on as an afterthought calculation, but simulated as part of the same worst-day physics as the buses themselves.

Step 2 — Run the worst-plausible day and read the combined result.


Service capacity (nameplate)	2,500 kW
Modeled charging peak (worst day)	2,250 kW
Spare after charging	250 kW

Step 3 — Open the Storage Business Case module. This is where solar and storage stop being static inputs and become a decision-support tool: the module lets the depot's planners sweep battery size against a target peak, finding the smallest BESS that holds the depot under a chosen ceiling — never sizing the battery for the operator, but showing exactly what each candidate size buys them, with a directional demand-charge savings estimate priced against an entered utility rate.

Step 4 — Confirm the 24-hour load profile tells a clean story. The interactive load chart overlays managed charging, BESS discharge/recharge, and solar offset on the same timeline — letting a planner see at a glance whether the battery is actually doing peak-shaving work during the hours that matter, or just idling.

Yinchuan Depot 24-hour load profile: overnight charging to 2,250 kW, daytime solar offset

Step 5 — Check every node holds, all the way downstream. With three electrical nodes in the chain — service entry, transformer, and circuit — the per-node view confirms the depot's full topology stays inside its ratings at the modeled peak, not just the headline service number.

The Result

The Depot Digital Twin confirmed Yinchuan's compact 45-bus depot holds its worst-day peak at 2,250 kW against a 2,500 kW service — 250 kW of spare capacity — with solar and storage modeled as active, load-shaping assets rather than static line items. This validates the core finding of the published study of this exact depot (Ma et al., 2025), which found that integrating PV and battery storage at this depot scale delivered a 37% reduction in total costs, a 41% cut in carbon emissions, and a 49% reduction in grid load over the battery system's operating lifetime — proof that the combined-asset approach pays off even at a mid-sized, single-depot scale, not just at flagship mega-projects.

Why It Matters

"A mid-sized transit operator doesn't need a hundred-bus flagship project to justify solar and storage — they need proof that it works at the scale they actually have."

For the majority of transit agencies that operate depots in the tens, not hundreds, of buses, this is the case that matters: solar and battery storage integrated into the electrical model from day one, sized and validated against the depot's own real worst-day physics.