Neighborhood Transformer Question

[SageBrush]

During the winter I can easily time shift my EV charging to just about any time of the day, so I wondered what would be the most beneficial to my utility. This is not really an energy source question since the majority of the energy bought by the utility from their wholesale supplier is coal; it is more a question of neighborhood and utility load.

So to start, a trivial and artificially simple question:
If my neighborhood transformer supplies two homes,
One is sending 5 kW to the transformer,
and the second home is pulling 5 kW from the transformer,
What load is on the transformer ?

 

[Lloyd]

Zero, nothing goes back to the utility feed.

 

[Ampster]

Zero, nothing goes back to the utility feed.

And that demonstrates the benefits of Distributed Energy Resources. Even if your one neighbor isnt using all that you produce, other neighbors will use it and the load at the substation will be reduced.

 

[RandyS]

Transformer Efficiency, Losses and Heat

There are two different types of losses in transformers (load and no-load). So even in your example of 5 kW input from one residence and 5 kW out to another residence, there would still be some no-load losses on the transformer that are due to it being energized...

 

[SageBrush]

And that demonstrates the benefits of Distributed Energy Resources. Even if your one neighbor isnt using all that you produce, other neighbors will use it and the load at the substation will be reduced.

Folks, please pity the moron (me) and answer the question directly.

Thanks ;-)

@RandyS seems to be saying that the net load on the transformer is zero, although some energy losses occur just to keep the transformer working. If this is correct, then am I likely correct in choosing to charge up my EVs at night ?

P.s., another newbie question:
Is load proportional to current flow through the transformer ?
Can I correctly restate my OP question as to whether current is flowing through the transformer ?

 

[Lloyd]

I believe the utility tells you when it is most beneficial by the rate reduction with TOU. When the rate is the least, that is when they want you to charge.

 

[strider]

Some utilities (like mine), don't do TOU in the winter. On my TOU tariff, there are only peak/off-peak times from June-October inclusive. Winter is straight consumption and the rate actually goes down the more you consume.

Here's my $0.02 educated guess. I would continue to charge at night, possibly starting a bit early, around 11:00pm. Most people are in bed at at that point and not running appliances but the temperature will be 'slightly' higher than in the depths of the early morning and there will still be some residual heat in the house from human activities which should equate to fewer heaters are running at that time. I think the benefit would be minor but you asked about what would be "best".

 

[dhanson865]

I believe the utility tells you when it is most beneficial by the rate reduction with TOU. When the rate is the least, that is when they want you to charge.

Look at you fancy California users with your TOU. No such thing in my part of fly over country.

 

[Lloyd]

Look at you fancy California users with your TOU. No such thing in my part of fly over country.

Nothing Fancy! Just a method that they can dig into your pocket a little deeper!!

 

[nwdiver]

Look at you fancy California users with your TOU. No such thing in my part of fly over country.

The grid can provide ~40GW. Demand at ~5pm is 30GW but in a few hours it slumps to ~20GW. If not TOU what incentive do you propose to encourage people to use less electricity when power capacity is scarce and shift that use to when it's abundant so we don't have to spend more $$$ on additional transmission and generation?

Some form of TOU is the most important component of cleaning up the grid.

 

[mspohr]

The grid can provide ~40GW. Demand at ~5pm is 30GW but in a few hours it slumps to ~20GW. If not TOU what incentive do you propose to encourage people to use less electricity when power capacity is scarce and shift that use to when it's abundant so we don't have to spend more $$$ on additional transmission and generation?

Some form of TOU is the most important component of cleaning up the grid.

Paradoxically, my utility (Liberty, in California) doesn't permit TOU tariff when you have solar net metering.
I assume they made this rule to keep me from making money on my solar when I feed excess power midday (peak time) and charge my car at night at a low rate. Seems counterproductive.
So, I charge my car when it's convenient for me, not the utility.

 

[dhanson865]

The grid can provide ~40GW. Demand at ~5pm is 30GW but in a few hours it slumps to ~20GW. If not TOU what incentive do you propose to encourage people to use less electricity when power capacity is scarce and shift that use to when it's abundant so we don't have to spend more $$$ on additional transmission and generation?

Some form of TOU is the most important component of cleaning up the grid.

I didn't say I was against TOU. I said I didn't have one. Why so combative over a simple statement of fact?

I'd be fine with rates that change in real time or in hourly blocks or a set TOU schedule. I don't have any opposition to any scheme that encourages conservation when load is the highest or when conditions are severe and risk partial grid failure (high winds, rain, hail) or when the utility needs to do maintenance on a plant or any reason I haven't though of that would justify modifying rates for short periods.

I just happen to live in TVA land and my local utility KUB doesn't do TOU. Maybe you should take your anger out on KUB (Contact Form).

 

[nwdiver]

I didn't say I was against TOU. I said I didn't have one. Why so combative over a simple statement of fact?

I'd be fine with rates that change in real time or in hourly blocks or a set TOU schedule. I don't have any opposition to any scheme that encourages conservation when load is the highest or when conditions are severe and risk partial grid failure (high winds, rain, hail) or when the utility needs to do maintenance on a plant or any reason I haven't though of that would justify modifying rates for short periods.

I just happen to live in TVA land and my local utility KUB doesn't do TOU. Maybe you should take your anger out on KUB (Contact Form).

I was being inquisitive. Not Combative. I get a lot of pushback when I propose TOU here. People don't want the utility to 'Tell them when to use electricity'. That's fine... if people want to use electricity without regard for abundance then they should pay the spot price NOT the average daily price. If my neighbor is paying $0.10/kWh at 4pm when the cost is really $0.50/kWh then I'm subsiding that...

Flat rates are a facade. Making something look simple on the outside doesn't mean it's simple on the inside. If someone doesn't favor TOU I'd like to know what they do favor and why....

 

[SageBrush]

If my neighbor is paying $0.10/kWh at 4pm when the cost is really $0.50/kWh then I'm subsidzing that...

Ha !

How apropos.

 

[dhanson865]

I was being inquisitive. Not Combative. I get a lot of pushback when I propose TOU here.

I gave you no such push back.

You do understand you are quoting my posts and I'm getting notifications about your tirades about TOU when I said nothing to oppose your view? If you wish to make an entire thread about TOU just do it without quoting me every time you have a new missive.

If you wrote something less pointed I might mark it like or informative but the way you are quoting me and going on I can only take it as combative. And I have no interest in arguing for the anti TOU point of view with you. I didn't sign up for that role.

 

[nwdiver]

I gave you no such push back.

Sorry. Meant 'here' in NM not 'here' on TMC.

 

[dhrivnak]

As MANY here I do not have TOC. But I think it is a fair question and between 10 pm and 4 am is likely a great time to charge as the grid normally has a lot of excess capacity then. But if you have solar, as I do, I start my charge at 10 am as I am trying to use the power I generate as our utility was trying to hit us with usage and demand charges.

 

[Ampster]

Can I correctly restate my OP question as to whether current is flowing through the transformer ?

Yes, current is proporional to Watts(power), assuming the same voltage