Where and How to install public EV charging stations

I’ve been bitten by some poorly placed EV charging stations, so I thought I would write this up…

1. Are the charging stations located somewhere where they will be used?

In other words, are people going to keep their car there for sufficient periods of time to have a meaningful charge. The amount of time someone will spend with their car in the parking spot must match the amount of time to get a useful charge from the charging station. Installing an “slow-charge” 240V 3.3/6.6kW EV station at a fast-service place (e.g. McDonald’s) makes little sense – you’re better off installing a fast-charge station for a fast-service place (DC fast charging – although not many cars will support this anytime soon, and stations are relatively expensive). A 20-minute DC fast-charge can replenish up to 100 miles of range.

At places like movie theaters, shopping malls, etc. it makes more sense to install the 240V chargers – patrons will be there for 2-4 hours using the facilities. This translates to anywhere from 20-50 miles of charge, depending on how quickly the car can charge.

2. Do you plan on charging a fee for the charging stations? If so, can you set a reasonable price or is it too much of a headache? 

For most 240V charging stations, the amount of electricity doled out is about $1 per session. How do you monetize this small of a transaction profitably? Can you do it at all, or is it better to just give it away for free? Charging on a per-session level is difficult because the amount of time people charge and the amount of electricity they will draw will vary from person to person. Charging on a per kWh basis is problematic because it doesn’t scale well the longer you charge. Charging on a time-basis means that people who can only charge a 3.3kW pay twice as much for the same amount of electricity as compared to charging at 6.6kW.

An alternate system would have a both session and kWh cost – 50c per session, plus 1.5x the cost of a kWh. So in my area, that would be 50c per session plus 18c kWh. A full charge would cost me $2.48 (11kWh for the Volt) for roughly $1.20 of electricity. Its still cheaper than a gallon of gas (which is what people will compare it to) and would take me about 35 miles. This also would cause cars with smaller batteries (Plug-in Prius, Ford Energi series models) to stay away and leave the spots open for pure EVs and longer range plug-in cars.

One of the best options is the traditional all-you-can-eat style flat rate plan. This would allow unlimited charging at your EV charging stations for users. This works best at a place like a parking garage or gym membership where it can be added on to another annual charge, reducing per-transaction costs. The charge for this will vary depending on the expected usage pattern (charging every night vs. a few times a week at a gym or occasional use).

Finally, there is always the free option – the one-time cost of construction, plus a small amount of money each month (in the neighborhood of $100 per charger) considered the cost of attracting customers, a marketing expense. The free plan also might be required – if your state has stringent rules about who can offer electricity for retail sale, you might have no other option but to give it away for free.

3. Are they public or behind a valet or in a private lot?

A charging station in a public lot might be ICE’d (occupied by a non-EV). But behind a valet or in a private lot, its easier to keep them free for EVs. At places like hotels, you will want to put some charging stations behind a valet, so that they can manage the car charging (e.g. when a car is full, have the valet move it to a regular spot and then bring in the next EV to charge).

4. What is the EV sales in the area? Are they common or uncommon? What outside conditions (state rebates, climate) affect purchasing an EV? 

Installing a charging network in a region or locale where EV cars are uncommon may not be a good idea. Check the utilization of current facilities before adding more.

5. Are you planning on expanding this charging infrastructure in the future? 

If you want to have just more than one or two token charging stations, it may help to install the electrical and underground infrastructure in one go – things like circuit breakers, transformers, conduit, etc, should be sized to handle your future expansion plans when EVs become more common. You wont need to have every spot in your parking lot charger-accessible, but build out for 5-10% of all parking spots having a charger, at 6.6kW for each car.

You may want to consider designs that allow for four cars to share two charging posts, this will reduce infrastructure costs and allow more flexibility for cars who want finish their charge and unplug but don’t have to move their car immediately.

6. Can you cost-share with others that share the parking lot or neighborhood? 

In the early stages of EV adoption, it may help to have multiple companies advertise that they have EV charging stations available for use. This may increase utilization initially and bring down initial costs.

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