[stlww18]

Hi all, two questions I am looking for guidance on before I bring an electrician in.

1) I've attached a pic of my 200 amp service; how large of a Level 2 charger do you think I could put on this panel? 50 amp AC, 40 amp range, and a 70 amp subpanel that runs my wood shop.

2) As an alternative to intelligent power backup, could you use a 240 generator input (like you'd use for a gas generator) and just plug the 240 from the tailgate into it? I am getting the standard range and don't have budget for charge station pro, nor do I have 100 amps of capacity available.

 

[ChasingCoral]

Add up your existing breakers to see how much of your 200A is in use.

 

[stlww18]

Add up your existing breakers to see how much of your 200A is in use.

My understanding was it was more complex than that; 200A of 120 on each pole means that just adding the amperage together doesn't really work when considering a 240 circuit is what I was reading.

 

[208]

2) As an alternative to intelligent power backup, could you use a 240 generator input (like you'd use for a gas generator) and just plug the 240 from the tailgate into it? I am getting the standard range and don't have budget for charge station pro, nor do I have 100 amps of capacity available.

As someone who installs solar and backup gensets, I see no reason why this would not work.

 

[208]

My understanding was it was more complex than that; 200A of 120 on each pole means that just adding the amperage together doesn't really work when considering a 240 circuit is what I was reading.

It is not terribly complicated, but it can be helpful to use watts instead of amps when considering your loads. W=A*V, so a 1a draw off one poll (120v) = 120w. Draw 1a off both polls and you draw 240w. A 200a 240v service in theory can provide 48,000 watts, more commonly noted as 48kw.

Your breaker sizes can give you a very rough idea of remaining capacity, but it is far more accurate to inventory what is connected to the breakers. As an example, if you have a breaker that powers a welder outlet, but no welder? In this case, you of course do not need to consider this as used capacity, etc.

 

[Cutler03GT]

2) As an alternative to intelligent power backup, could you use a 240 generator input (like you'd use for a gas generator) and just plug the 240 from the tailgate into it? I am getting the standard range and don't have budget for charge station pro, nor do I have 100 amps of capacity available.

Yes. If you get the 9.6 kW Pro Power Onboard option, you can use it with a generator transfer switch, if you get the right type. It needs to be compatible with a “bonded neutral generator”.
See this article for some additional details.

How to Avoid Tripping a Generator with a Bonded Neutral - Kyle's Garage

A GFI transfer switch eliminates your tripping generator problems. Read this article to find out how.

kylesgarage.com

 

[jodgey]

My electriciman gave me the reference below. It’s more involved than direct power, ie volts x amps. You can only use 80% of available power, but they have a bunch of knock down factors that assume you are turning on your pool pump at FLA while starting your dryer at FLA while making coffee, while slamming your AC to freezing while cranking Your furnace at full blast.
anyway, it’s what he uses to determine capacity.
also told me an interesting nugget the other day. That the power company charges you a multiplier based on your max power draw at a moment each month. So, spread your high power appliance usage out, if you can, and you will reduce your multiplier and thus your utility rate.

I use the form from Mike Holt residential calculation online.which is an excel speardsheet

 

[PatrickC]

There’s no limit to the number of breakers you can have in the panel. If there’s a slot available, you can add a breaker. It doesn’t matter if the total breakers add up to 500A in a 200A panel. The issue you need to consider is called “diversified load.” In other words, how much power are you likely to draw at any moment.
It’s a little hard to tell but it looks like you have room for a full size tandem breaker so you could put a 100A breaker there if your diversified load wouldn’t trip the main. But if you aren’t going to get a big charger, then go for the 32A or 48A (40 and 60A breakers, respectively) chargers.
You should be able to install a plug and transfer switch to connect the 7.2kW 240V outlet on the truck to the house, just like you would with a portable generator. That would require a 40A breaker.

 

[Pdr1966]

Following

 

[SCVLightning]

As someone who installs solar and backup gensets, I see no reason why this would not work.

question for you, can any electrician install the 80amp with intelligent backup power? Do they have to do something special to allow for the flow of power both ways?

Or does this have to be done by Sunrun?

 

[R.I.P.]

question for you, can any electrician install the 80amp with intelligent backup power? Do they have to do something special to allow for the flow of power both ways?

Or does this have to be done by Sunrun?

There is nothing special that has to be done to get the power to flow both ways. In layman's terms, electricity flows from "high pressure" to "low pressure" automatically, much like water. If you are making power, and your pressure is higher than the grid, it will push it back into the grid. If you are using more than you produce, it will pull from the higher grid pressure.

Any qualified electrician will be able to make the appropriate connections for you.

P.S.
It is this principle that makes rooftop solar such a good combination with an EV. You do not have to do anything special for the power generated on your roof to dump directly into the EV that you have plugged in and charging. This will happen automatically if you are producing power, and you only pull from the grid any extra that the EV is requesting.

 

[SCVLightning]

There is nothing special that has to be done to get the power to flow both ways. In layman's terms, electricity flows from "high pressure" to "low pressure" automatically, much like water. If you are making power, and your pressure is higher than the grid, it will push it back into the grid. If you are using more than you produce, it will pull from the higher grid pressure.

Any qualified electrician will be able to make the appropriate connections for you.

P.S.
It is this principle that makes rooftop solar such a good combination with an EV. You do not have to do anything special for the power generated on your roof to dump directly into the EV that you have plugged in and charging. This will happen automatically if you are producing power, and you only pull from the grid any extra that the EV is requesting.

that’s very helpful. Thank you