On 03/04/16 22:49, Andrew Gabriel wrote:
In article ,
Tim Watts writes:
On 03/04/16 20:46, bert wrote:
If lots and lots of people did it I suspect the grid would be stuffed.

It may not be - they would probably be doing it overnight mostly - and
there's a lot of spare capacity then.

Supplies to housing estates are worked out assuming an After Diversity
Maximum Demand (ADMD) rating per house, which is typically 2kW, but
dropping as low as 1kW for small terraced houses. (For electrically
heated homes, the electric heating load is added on top.)

If many homes plug in electric cars for charging even just at night, it
will blow the substation fuses at best. There was an incident in Luton
some years ago where a large number of gas meters were destroyed when
a high pressure gas main was accidentally connected to the street
supply, and the gas had to be disconnected from a housing estate for
some days whilst all the gas meters and regulators were replaced. The
gas company dropped off a 2kW fan heater at each house. Then they all
lost their electrical power when the substation transformer literally
blew up.

Changing the power distribution for vehicles from petrol tankers over
to electricity supply network will require a significant upgrade of
the supply network, never mind the generation plant.


The one thing here though is, unlike the 2kW heaters example, it's not
all going to happen at once - unless the government do something to
intervene.

32A single phase is 7.3kW and a full 11 hour charge at that rate (Model
S) equates to over 250 miles of driving (winter heating not factored)
IIRC. So you won't have the situation where everyone is fully charging
every night.

Also those 2kW heaters would have been on in the evening at the same
time as all the normal load.

Clearly you're right that ultimately, the system will need upgrading -
but I think there's going to be time to deal with that provided people
do actually charge the things overnight on cheap rate.

I'd say the biggest problem is the generating capacity and the
"destination" and superchargers that will get used heavily in the day.
In London, there are a number of day time charging points springing up
that generally have a Nissan jacked in all day while someone is at teh
office. Trivial number now, but it could grow.