Stellos Playbook · EV Charging

How Many EV Chargers Does Your Parking Need?

Let me tell you about the two most common EV-charging mistakes, which are opposite mistakes, and how to land between them. To show you how, let me start with a little story about two garages.

Stellos operates parking technology across Switzerland and Germany, trusted by teams at Google, Swisscom, Implenia, Wincasa, CWS and Sony.

A tale of two garages

The first garage installed twenty chargers in a burst of ambition. Most days, three are in use. The capital is spent, the spots are reserved for cars that rarely come, and the finance team is unimpressed. The second garage installed two, to be careful. By nine in the morning there is a queue and a sign-up sheet taped to a pillar, and the careful choice now looks like the expensive one. Both got the number wrong, in opposite directions, because both started from a hunch.

Start with the ratio, not the hardware

So let me give you the frame that works. You are not really choosing a number of chargers, you are matching charging supply to how cars actually dwell. A spot where cars sit all day needs far less power per spot than one that turns over hourly, because an all-day car can charge slowly and still leave full. The useful question is not "how many chargers" but "how many charging spots, at what speed, for the way cars use this place." Office and residential parking, where cars sit for hours, can serve many vehicles from modest hardware. High-turnover visitor parking cannot.

The cheapest charger is the one you do not install yet

Here is the move that saves the most money, and almost everyone skips it. When the floor is already open for the first install, run the conduit and capacity for far more spots than you energise today. This "make-ready" groundwork is the expensive, disruptive part (where EV cost really hides), and doing it once, in advance, turns every future charger into a quick, cheap add. You phase the visible hardware to match real demand while never trenching the floor twice.

Load management changes the arithmetic

And one more thing before you price a grid upgrade. Modern chargers can share a fixed amount of power across many points, throttling each so the building's supply is never exceeded. For parking where cars dwell, that is close to free capacity: you serve far more charging spots from the power you already have, and defer or avoid the expensive upgrade entirely. Measure utilisation first, let it tell you when to energise the next make-ready spot, and the number sizes itself. For the wider picture, this sits inside parking and EV charging strategy.