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We a are installing car charging points for our residents and have been quoted £40K plus for the power supply from National Power for 24 7.5K charging points. The tranformer that the power is coming from is in the car park. Our distribution board is almost bolted to the size of it. I am struggling to find any data to establish if these costs are reasonable. Any help appreciated
 

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You say "residents". How many of these have Evs, and what's the usage? a 7kW (32A) EVSE will give you about 20 miles range for each hour plugged in (ballpark figure, obvs varies per EV, time of year, driving style,...). Are you likely to see occasional residents arriving early with empty Ev, then plugging in on that for 6 or 7 hours to completely fill a 40 kWh EV? If so, that's one EVSE tied-up for the day that no-one else can use. Would you prefer instead to fit 16A EVSEs that would give around 10 miles per hour plugged in, as you can have 2x as many for the same max total power consumption. If your residents all tend to drive locally, maybe they're retired pensioners like me, that may be a better fit to the usage requirements.

EVSEs can run as low as 6A, that's the minimum they can be set to, so 1.5 kW. This will give EVs around 5 miles per hour plugged in, and may well be perfectyl enough for anyone doing no miles on most days, but likes a trip out at the w/e.

Fitting 1.5 kW EVSEs lets you have 5x as many, compared to 7 kW ones. (6A .vs. 32A).

Plugged in overnight on 1.5 kW for 12 hours is good for around 60 miles range - that's like handing out a free gallon of petrol so is a pretty generous thing in itself, despite sounding like a miserably low qty of electricity. It isn't.

So you may do better if you have a mixture of powers available; a lot of 1.5 kW, for the "background charging, not urgent" residents, and maybe just a few 7 kW for those doing more travel, and for visitors who may have come a long way & are only staying a few hours before a long trip back.
 
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We a are installing car charging points for our residents and have been quoted £40K plus for the power supply from National Power for 24 7.5K charging points. The tranformer that the power is coming from is in the car park. Our distribution board is almost bolted to the size of it. I am struggling to find any data to establish if these costs are reasonable. Any help appreciated
Sounds about right. What Available capacity in kVA is that?
 

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For £40k it is likely that you are having to have a network upgrade with a new transformer and cabling to it. As @mikeselectricstuff says it is worth asking what the maximum that you can draw for no additional cost is, and whether there are any pricepoints in between.
Also as @HandyAndy says, you may well be able to advertise "up to 7kW charging" but load limit to keep the total under one of the pricepoints.
 

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How many flats that previously had storage heaters now have central heating? That's a nice big chunk of spare power right there, that I suspect the person quoting you has conveniently overlooked.
 

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How many flats that previously had storage heaters now have central heating? That's a nice big chunk of spare power right there, that I suspect the person quoting you has conveniently overlooked.
Is there any way that they could look at, say, the last year's actual demand to establish what thd actual current loading is? Or maybe they already did that when determining that an upgrade was needed. Could be worth asking.
 

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24x 7kW chargepoints would require their own (mini) substation. I'd say £40k sounds fairly reasonable.
 

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24x 7kW chargepoints would require their own (mini) substation. I'd say £40k sounds fairly reasonable.
Or using charge points that can load balance you could use a smaller supply, these say you can have up to 101 on a single circuit (32a three phase from what I understand).

 

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I don't know about the price, just wanted to point out:
  • 24 * 7.5kW = 180kW
  • Or 24 * 32A = 768A
  • These numbers will have to be adjusted for losses, so probably the plan will be install 1000A/220kW.
That is what your DNO is planning for your installation. That is not a small feat.

Check your substation or transformer, that will give you the available capacity, but you will not know what is already dedicated to users.

Load sharing chargers seems like a good idea. But you need to know what the DNO has available or planning.
 
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