Demand factor on electric car charging

[Fjahnke@premiercorp.net]

Our company has a high rise condo project. The developer wants to have an electrical car charging unit for each parking space. There are 218 unit parking spaces. My question is that is there a demand/ diversity factor that you can apply to the total connected load. They obviously won’t all be used 100 % of the time. I am thinking like the demand factor for electrical ranges in the units. Is there any code articles that apply?

 

[kingpb]

Well from what I've seen around town at the parking lot charging stations the demand factor may be about 0.5%; but that may be a tad low.

 

[drktmplr12]

Well from what I've seen around town at the parking lot charging stations the demand factor may be about 0.5%; but that may be a tad low.

0.5 as in 50%?

 

[gadfly56]

0.5 as in 50%?

I believe he means as in "One out of 200 spaces."

 

[JFletcher]

As far as I know, unless there are local amendments, these chargers would have a 100% demand factor.

This would obviously result in a much larger electrical service then what is needed.

One option would be to run conduit to each parking spot, and put in EV Chargers as needed. Perhaps the code will catch up in future years to apply a demand factor of say 20% for more than 200 units, perhaps someday there will be 218 electric vehicles all charging in those spots. For today, I don't know of any demand factors one can apply.

don't quote me on this, however the poster Charles Beck, who I believe is in Seattle, had commented about demand factors on electric vehicle chargers. Perhaps faulty memory, perhaps at best a citywide Amendment to the NEC. Check with your ahj to see if there are any local amendments.

And welcome to the Forum

 

[pv_n00b]

I don't know of any standard demand factor, it's still a new load so not much has been studied. I do know of people who complain that they have two car chargers and if they have both in use the branch breaker trips so someone was not thinking when they set that up. Eventually, someone will come up with a demand that will look something like the first X kW of chargers are at 100% and the rest are at 50% or something like that.

 

[drcampbell]

... They obviously won’t all be used 100% of the time. I am thinking like the demand factor for electrical ranges in the units. ...

I'm afraid it's all pure speculation at this point -- how many electric vehicles, what schedules, how will smart chargers interact with each other to share the available power? But you won't be able to use the same demand factor as for electric ranges; when you first begin charging a vehicle, it'll draw 100%. If the vehicle's been driven a lot, the charger will maintain 100% for several hours.

But if the developer has the budget and mindset for a car charger for each parking space, be sure to upsell him as many solar panels as will fit on the roof.

 

[broadgage]

IMHO, it would depend on how many parking places are provided in total.
If there are 218 places is total, all with chargers, then initially at least the percentage used by electric vehicles will probably be small.
If however there are 1000 spaces, 218 of which are electric, then a larger demand seems reasonable.

It also depends on how fast the chargers are. In the case of fast chargers it is likely that those vehicles that plugged in first will be full before later arrivals start charging.
With slow chargers, the first arrivals will still be charging when more arrive.

The actual demand factor is unknown, but likely IMHO to increase substantially during the life of the installation.

UK practice is to allow for the for the first few chargers at full load, and the remainder at 50%. This seems to be common practice but is not AFAIK supported by any regulation or requirement.

 

[Besoeker]

Yes. Lots of unknowns.
EV ownership is not a high percentage of total vehicle ownership. Less than 1% in 2014. Would that be reflected in a condo?
Sales are going up almost exponentially. But limited range and recharge times are still a limitation for many. A few weeks ago, I did a 600 mile round trip in a day. No EV currently available could do that.

 

[jaggedben]

Someone posted somewhere on here relatively recently that some chargers can be programmed in groups to limit the overall output. That is, the more that are in use, the less each one outputs. If you've got something like that (which I think you should, anyway) I think you can use it in calcs. If not I agree there is a lack of code guidance and you may not get to use a factor.

 

[kingpb]

I'm afraid it's all pure speculation at this point -- how many electric vehicles, what schedules, how will smart chargers interact with each other to share the available power? But you won't be able to use the same demand factor as for electric ranges; when you first begin charging a vehicle, it'll draw 100%. If the vehicle's been driven a lot, the charger will maintain 100% for several hours.

But if the developer has the budget and mindset for a car charger for each parking space, be sure to upsell him as many solar panels as will fit on the roof.

And a setup for battery energy storage to store the solar power until evening time when the millennial's get home and want to plug their toy cars in.

 

[Besoeker]

And not drive them again during the hours of darkness....