EV max demand vs. Normal high load reporting to DNO

Why notify one and not the other?

Simply because the sustained “domestic load” isn't 15 kW, roughly £3 an hour as this would equate to a weekly bill of £500…………………………………….. An interesting example would be to take your quarterly kWh usage and calculate your average load. It might be typically 0.6 kW.

Yet, do the same for a 7 kW EV load charging a 50 to 90 kWh EV battery three times a week and see why the DNO have concerns……………………….

Regards

BOD

perspicacious: 
 

Why notify one and not the other?

Simply because the sustained “domestic load” isn't 15 kW, roughly £3 an hour as this would equate to a weekly bill of £500…………………………………….. An interesting example would be to take your quarterly kWh usage and calculate your average load. It might be typically 0.6 kW.

Yet, do the same for a 7 kW EV load charging a 50 to 90 kWh EV battery three times a week and see why the DNO have concerns……………………….

Regards

BOD

Makes sense. 

So it’s the continuous use that’s the issue and not the actual peak.

For instance, the install could peak to 60-70A for a period of time, whist someone is cooking + showering + heating, but this would taper off as things are shut down. 

An EV charger is different, if six houses all had EV chargers running it’s a continuous load for long periods of time. 

BOD makes a good point. Another high consumption load would be a swimming pool heater. Daughter's first quarterly leccy bill was £900, but that's a nice steady load.

When I discussed load with SSE, they seemed to be concerned about large motors - you don't want the neighbours' lights dimming - but 3-phase seemed to be much more acceptable. I can draw 69 kW (or more briefly!) but the agreed ADMD is only 30 kW. If it ever got that high for a significant period I would wince. ?

Chris Pearson: 
 

BOD makes a good point. Another high consumption load would be a swimming pool heater. Daughter's first quarterly leccy bill was £900, but that's a nice steady load.

When I discussed load with SSE, they seemed to be concerned about large motors - you don't want the neighbours' lights dimming - but 3-phase seemed to be much more acceptable. I can draw 69 kW (or more briefly!) but the agreed ADMD is only 30 kW. If it ever got that high for a significant period I would wince. ?

What if the maximum demand is already above 60A and the consumer wants to add an EV charger? 

The rule is that you have to get permission from the DNO if the “new” maximum demand is >60A, but what if the current (before EV charger is installed) maximum demand is already above 60A? 

An energy management solution in the EV would stop the charger if it measures a load over 60A, so adding an EV charger would have little to no impact on the current, household maximum demand. 

A cynic like me would suggest that EVs are the “new big thing” and that the DNOs see a large pot of gold of which they want a share.

My view is that if the supply is 60 amps, then the customer should be able to use 60 amps for any legal purpose.

If enough people use 60 amps, then the DNO network will have to be upgraded, and this will be paid for out of the extra revenue.

EV charging is in many respects an ideal load, often off peak as that is when most customers sleep and potentially charge their vehicles. It is a long hour load that produces significant revenue.

Most businesses would be glad that customers are buying more of their product. 

Have Tesco ever said to a customer “you have been buying too many groceries from us, and we therefore require that you contribute £921-97 to the cost of building our new distribution center”

We are already billed a daily “standing charge” on our bills, which is supposed to go on maintaining the network.  But the different electricity companies can set the standing charge at whatever price they want, so it's doubtful that it's really being used for its intended purpose.

I was recently talking to a Western Power guy on a site visit. He told me that, due to EV chargers, where they previously had to supply 2.5kw to a new build, the spec has changed to 13.3kw per plot. He said that it has pushed costs through the roof for developers

What a surprise!

I have several times explained that this is going to go horribly wrong and quite soon. There is little reason to ask the DNO, they are not really in a position to do much at all, because the entire supply system is fairly close to breaking point. It was never designed for these large continuous loads from domestic properties, and to start to change that would be ruinously expensive. The question of who pays to cost, probably £3 Trillion, and the immense disruption everywhere is the question to ask your MP, along with where the labour and skills necessary are going to come from. Maybe this is what then mean by highly skilled “Green” jobs being created, we need huge capacity in making large transformers, cables, construction civils,  road barriers and traffic cones! The raw materials are not available on the world market, and reducing oil refining will make the insulation in short supply too.

This is far too large a problem for MPs to understand, and can the public understand the size of the mess they will create when taking advice from accountants and “Green experts" who don't have a clue either? Good luck there then! They certainly don't listen to the professionals, but then neither do the journos writing E&T!

vantech: 
 

Why notify one and not the other? 

The answer to this question is very simple.

Whilst you may have a service head with a 100 A fuse holder, the fuse inside may well be 60 A or 80 A.

There are a number of different reasons for this, but basically, for most properties, until an EV charger is required it's not really a problem.

So, you notify the DNO if your MD (including EV) will exceed 60 A.

The DNO will then be able to do whatever they need to do. In some cases, it's as simple as replace the fuse, in others it may involve upgrading the service cable, reinforcement of local network, etc.

Occasionally there's a minor problem that some of the not-so-smart meters have to be protected by an 80 A fuse, and there's nothing the DNO can do about that. In those cases, the largest service fuse you will be given is 80 A.