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EV Charging → Question 3

How Big Should Each Station Be?

Model A gives every station 8 ports — 111 stations, 888 ports total. Model B sizes them by real demand: 49 stations, 948 ports, and the top 10 all need 20 ports at 3.0 MW each. That exposes a new problem: the grid.

Optimal Port Count vs Peak Demand (kW) — Real County Data

Model A under-sizes high-demand stations: 8 ports for Harris County, which has peak demand of 74,877 kW? And it wastes budget on 111 scattered stations. Model B concentrates into 49 demand-matched stations — most top sites get the maximum 20 ports because the optimizer finds high-demand locations first.

Model B delivers 948 total ports vs Model A's 888, with 56% fewer stations. But the top 10 stations all need 20 ports at 150 kW each = 3.0 MW per station. That reveals a constraint the flat model never had to face.

Station-by-Station Comparison

County Peak Demand (kW) Model A Ports Model B Ports Model B Power (MW)
Harris (Houston) 74,877 8 20 3.0
Dallas 66,452 8 20 3.0
Tarrant (Fort Worth) 46,550 8 20 3.0
Bexar (San Antonio) 28,255 8 20 3.0
Travis (Austin) 14,265 8 20 3.0
McLennan (Waco) 3,800 8 6 0.9
Potter (Amarillo) 2,100 8 4 0.6
Midland 1,500 8 4 0.6

20 ports at 150 kW each = 3.0 MW per top station. That's the equivalent of powering 2,400 homes — a significant grid connection that requires a dedicated substation tie-in. Model B total: 948 ports vs Model A's 888 ports, but concentrated in fewer, larger stations.

Model B's top sites near AIRLINE substation (Harris), TAP305257 (Dallas), and TENTH STREET (Bexar) each need 3.0 MW — and those substations are already 70–78% loaded. Model A never sees this because 8 ports at 150 kW = only 1.2 MW, which fits within existing headroom.
Finding
Model A under-sizes high-demand stations (8 ports for Harris County?) and wastes budget on 111 scattered stations. Model B concentrates into 49 demand-matched stations — but its top 10 all need 3.0 MW grid connections. The optimizer finds the right size but exposes a grid constraint the flat model can't see.

Sizing: ports = ceil(peak_demand / port_power / target_utilization). 150 kW per port. Real demand from Census + TxDOT + TX DMV data. 4,151 substations checked for grid capacity.