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Adding EV charging into my PV/ESS setup

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h2ofun

Active Member
Aug 11, 2020
4,742
1,369
auburn, ca
I want to add some EV changing stuff into my house while I still have the sheet rock torn apart. Looking for any experiences on my options.

Currently I have an empty generation 200amp panel. Am thinking of putting 3 60amp breakers in it for 3 EV charging stations in my 3 car garage.
I assume I will need to get permits for this. Since it is on the output of the Gateway, I am assuming no issues with my down stream generation panel
for the batteries and solar, generator transfer switch or house subpanel.

Is it possible to wire this but not put the charging heads on now and pass a code inspection?

Any options on best EV charging head?

Anything else I should consider before doing this?

When do folks normally charge their cars? When there is no solar? Does one draw from the battery?
 
We have 3 load balanced gen 2 wall connectors that are on a shared 100 amp circuit. This allows 80 amps to be shared between 3 cars at once. Depending on which EVSE equipment you choose, you might be able to share one 60 amp breaker instead of having 3 separate breakers.

We have our Powerwalls set to Balanced mode and usually power the house for all but a couple hours of the day. We have things set to switch over to grid power at 3 am and that's when one car starts charging. It always charges from the grid at off-peak rates. A second car usually charges around 6 am and usually is charged with a combination of off-peak grid power and leftover Powerwall energy. We charge cars at this time since the rates are the cheapest and it allows us to keep a charge in the Powerwalls until the sun comes back up. Also, the motors and batteries are heated up so that regen is still pretty good on cold mornings. We have a third car that charges via solar around noon. If our work schedules were different, we'd charge more from solar as it would be more efficient than charging from the Powerwalls which have about 90% efficiency.

If there's a grid outage, the cars, wall connectors and Powerwalls will work together to stop charging so we don't have to worry about draining our Powerwalls overnight.
 
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We have 3 load balanced gen 2 wall connectors that are on a shared 100 amp circuit. This allows 80 amps to be shared between 3 cars at once. Depending on which EVSE equipment you choose, you might be able to share one 60 amp breaker instead of having 3 separate breakers.

We have our Powerwalls set to Balanced mode and usually power the house for all but a couple hours of the day. We have things set to switch over to grid power at 3 am and that's when one car starts charging. It always charges from the grid at off-peak rates. A second car usually charges around 6 am and usually is charged with a combination of off-peak grid power and leftover Powerwall energy. We charge cars at this time since the rates are the cheapest and it allows us to keep a charge in the Powerwalls until the sun comes back up. Also, the motors and batteries are heated up so that regen is still pretty good on cold mornings. We have a third car that charges via solar around noon. If our work schedules were different, we'd charge more from solar as it would be more efficient than charging from the Powerwalls which have about 90% efficiency.

If there's a grid outage, the cars, wall connectors and Powerwalls will work together to stop charging so we don't have to worry about draining our Powerwalls overnight.
Thanks, as I guessed, many different ways to do this. I was just thinking if I had a dedicated 60 amp per charger, that this might make the wiring simpler but have no reason to think this.

I see there are many options for EV charging equipment. Of course, nothing jumps out as clearly the best. :(

Your charging process makes total sense.
 
Thanks, as I guessed, many different ways to do this. I was just thinking if I had a dedicated 60 amp per charger, that this might make the wiring simpler but have no reason to think this.

I see there are many options for EV charging equipment. Of course, nothing jumps out as clearly the best. :(

Your charging process makes total sense.
Since you have an empty 200 amp panel, you might as well use it if you can. In our case, our garage has a subpanel with circuit breakers for everything in the garage, including a 100 amp breaker which leads to another subpanel that contains 3 100 amp breakers. This allows each of the wall connectors to individually charge at up to 80 amps. Since the three wall connectors are load-balanced, they would never exceed 80 amps total. The second subpanel doesn't have a door so it allows individual wall connector breakers to be seen from within the garage. Some places have different requirements and might require a separate shut-off switch instead of allowing circuit breakers as our system uses.

While none of our cars currently allow 72 amp (common from 2016 to 2018 or so) or 80 amp charging (more common in Teslas before 2016), I'm glad they put a 100 amp breaker as it allows the 80 amps to be shared between the three wall connectors.

I think your idea to install 3 60 amp breakers would cost a little more than just installing one that is load-balanced by the EVSE but it would allow for more flexibility if you wanted to change things in the future.
 
Since you have an empty 200 amp panel, you might as well use it if you can. In our case, our garage has a subpanel with circuit breakers for everything in the garage, including a 100 amp breaker which leads to another subpanel that contains 3 100 amp breakers. This allows each of the wall connectors to individually charge at up to 80 amps. Since the three wall connectors are load-balanced, they would never exceed 80 amps total. The second subpanel doesn't have a door so it allows individual wall connector breakers to be seen from within the garage. Some places have different requirements and might require a separate shut-off switch instead of allowing circuit breakers as our system uses.

While none of our cars currently allow 72 amp (common from 2016 to 2018 or so) or 80 amp charging (more common in Teslas before 2016), I'm glad they put a 100 amp breaker as it allows the 80 amps to be shared between the three wall connectors.

I think your idea to install 3 60 amp breakers would cost a little more than just installing one that is load-balanced by the EVSE but it would allow for more flexibility if you wanted to change things in the future.
so are you using 3 seperate 100 amp breakers, one each for a charger, or 1 100amp shared by 3 charges.
 
so are you using 3 seperate 100 amp breakers, one each for a charger, or 1 100amp shared by 3 charges.

They have one 100 amp circuit that is shared between three tesla wall connectors that balance the load between them, dynamically.

Tesla generation 2 (Gen 2) wall connectors can share a circuit and load balance between them, so that the vehicles can all charge and split the electricity (and when one finishes, the other 2 can charge faster).

This is a feature of the tesla wall connector (gen 2). Some other wall connectors may provide that functionality as well.

With that being said, if you are wanting to do something NOW to prepare for later, the simplest thing to do is run 3 different 14-50 plugs (or 6 50s, or 14-30s or whatever your load calculation supports for 3 separate lines) to the location you envision the cars being.

EVs always come with some form of plug in adapter (the charger is in the car, in almost all cases, so the thing on the wall is called a wall connector, not a charger).
 
so are you using 3 seperate 100 amp breakers, one each for a charger, or 1 100amp shared by 3 charges.
Originally, we had 2 14-50 outlets which were in the garage subpanel (on the left below).

When Tesla came to install our solar, Powerwalls and wall connectors, they added the second subpanel (on the right) which has a 100 amp breaker for each wall connector. The 100 amp breaker on the left subpanel is for the wall connector subpanel on the right. The 50 amp breakers in the left subpanel are still there but no longer used. If we ever have issues with our wall connectors, we would switch them back on and charge that way temporarily.

Note that our gen 2 wall connectors were installed before the gen 3 wall connector was released. Now, I think they allow for a cheaper/simpler install where there's only one breaker shared by up to 16 (?) wall connectors at once (assuming they ever release load balancing for gen 3 wall connectors).


20210504_110507.jpg
 
If you don't have any cars yet, don't bother to install the charging equipment. Run the circuits to the appropriate locations and just put wire nuts on the ends of the wires and put a cover plate on. 60 amps to each garage bay is a great solution. In the future, you can drop down to put a 50A breaker and a NEMA outlet, or you can hard wire a 60A EVSE. Just make sure the wire is properly sized for 60A.
 
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Originally, we had 2 14-50 outlets which were in the garage subpanel (on the left below).

When Tesla came to install our solar, Powerwalls and wall connectors, they added the second subpanel (on the right) which has a 100 amp breaker for each wall connector. The 100 amp breaker on the left subpanel is for the wall connector subpanel on the right. The 50 amp breakers in the left subpanel are still there but no longer used. If we ever have issues with our wall connectors, we would switch them back on and charge that way temporarily.

Note that our gen 2 wall connectors were installed before the gen 3 wall connector was released. Now, I think they allow for a cheaper/simpler install where there's only one breaker shared by up to 16 (?) wall connectors at once (assuming they ever release load balancing for gen 3 wall connectors).


View attachment 659502
Sorry, still confused. So you have a 100 amp circuit to each wall connector? What wall connector are you using? whats is its max current? Was using a 100 amp breaker and wiring an overkill? what wiring did you use? Are the wall connectors hard wired, or do you have them wired to a box and the wall connectors plug in? So much to learn.
 
If you don't have any cars yet, don't bother to install the charging equipment. Run the circuits to the appropriate locations and just put wire nuts on the ends of the wires and put a cover plate on. 60 amps to each garage bay is a great solution. In the future, you can drop down to put a 50A breaker and a NEMA outlet, or you can hard wire a 60A EVSE. Just make sure the wire is properly sized for 60A.
That is what I am trying to at least do, assuming I can get it coded. Any reason to wire to 100amp per line? I technically can have 5 cars in my garage, one section is 60 feet long. So as I always try to do, trying to over design for max flexibility. I guess running 6/3 wire would be the best if I limit to a 60 amp breaker?
 
Sorry, still confused. So you have a 100 amp circuit to each wall connector? What wall connector are you using? whats is its max current? Was using a 100 amp breaker and wiring an overkill? what wiring did you use? Are the wall connectors hard wired, or do you have them wired to a box and the wall connectors plug in? So much to learn.
Yes, we have three Tesla generation 2 Signature wall connectors which are capable of charging a car at up to 80 amps each so they require a 100 amp breaker (when configured to charge at up to 80 amps). The wall connectors are all hard-wired and there is a signal wire from the master wall connector which is daisy-chained to the other two wall connectors. The master wall connector load balances the amps between the cars. If a friend came over with an older S or X, they would be able to charge at 80 amps. If we then plugged in one of our newer cars, the load would be split and each car would automatically get 40 amps. If we plugged in a third car, the load would be split again so that each was charging at about 27 amps. If a car finished charging, then the 80 amps would then be re-allocated to the remaining cars.

Teslas these days only charge at 48 amps so maybe anything above 60 amps would be overkill unless you happen to have an older car that can charge at 72 to 80 amps. It remains to be seen if the Cybertruck and next gen roadster will continue to max out at 48 amps or if they will support 72 amps or more.
 
Yes, we have three Tesla generation 2 Signature wall connectors which are capable of charging a car at up to 80 amps each so they require a 100 amp breaker (when configured to charge at up to 80 amps). The wall connectors are all hard-wired and there is a signal wire from the master wall connector which is daisy-chained to the other two wall connectors. The master wall connector load balances the amps between the cars. If a friend came over with an older S or X, they would be able to charge at 80 amps. If we then plugged in one of our newer cars, the load would be split and each car would automatically get 40 amps. If we plugged in a third car, the load would be split again so that each was charging at about 27 amps. If a car finished charging, then the 80 amps would then be re-allocated to the remaining cars.

Teslas these days only charge at 48 amps so maybe anything above 60 amps would be overkill unless you happen to have an older car that can charge at 72 to 80 amps. It remains to be seen if the Cybertruck and next gen roadster will continue to max out at 48 amps or if they will support 72 amps or more.
sounds like you ran 4 gauge wire to each connector.

I guess there is a balance between great and over kill. My 5 PW batteries are great, 7 would have been a total overkill.

Seems the great thing to do is run 6/3 wire with 60 amp breakers. Run these into a box wire with wire nuts for now, so I can get, when needed
the correct wall connector. Then I have to think is it better to run separate wires up my wall, or should I put another subpanel in my garage, so I only run one wire from the below subpanel. And then run the wiring from that. So many decisions. And then what size subpanel would I run since that wire gets big.
 
Yes, we have three Tesla generation 2 Signature wall connectors which are capable of charging a car at up to 80 amps each so they require a 100 amp breaker (when configured to charge at up to 80 amps). The wall connectors are all hard-wired and there is a signal wire from the master wall connector which is daisy-chained to the other two wall connectors. The master wall connector load balances the amps between the cars. If a friend came over with an older S or X, they would be able to charge at 80 amps. If we then plugged in one of our newer cars, the load would be split and each car would automatically get 40 amps. If we plugged in a third car, the load would be split again so that each was charging at about 27 amps. If a car finished charging, then the 80 amps would then be re-allocated to the remaining cars.

Teslas these days only charge at 48 amps so maybe anything above 60 amps would be overkill unless you happen to have an older car that can charge at 72 to 80 amps. It remains to be seen if the Cybertruck and next gen roadster will continue to max out at 48 amps or if they will support 72 amps or more.
Why did they drop the charge rate? Safety?
 
Why did they drop the charge rate? Safety?

Not sure but all current modern teslas only Level 2 charge at up to 48 amps. If I had to guess, it would be that:

1. Cheaper charging equipment in the car
2. Less onerous for the home owner to setup "max" charge rates
3. Thinner cabling etc needed for the wall connector or the mobile connector
4. Overnight charging fills up pretty much any current tesla even at 48amps.

Those are just guesses as to why, but I have a 48 amp connection to my tesla wall connector, and have never needed faster (or even "needed" as fast as I have).

I agree with @miimura though. Run 60amp connections to the location,s wirenut them off and dont do anything else unless and until you get an EV.
 
That is what I am trying to at least do, assuming I can get it coded. Any reason to wire to 100amp per line? I technically can have 5 cars in my garage, one section is 60 feet long. So as I always try to do, trying to over design for max flexibility. I guess running 6/3 wire would be the best if I limit to a 60 amp breaker?
Even if you can fit 5 cars, you don't need more than 3 charging stations unless you have more than 3 drivers in the household that would all need to charge at the same time. You still need to do a load calculation to see if you can really provision 3 independent 60A circuits. There may be some other limitation upstream of that 200A panel. I don't know your overall topology, just that you have a two gateway Powerwall setup.

You can only use 6ga if it's THHN or equivalent in conduit. If you want to use Romex, you have to go to 4ga for 60A. IMHO, there's no need to go to 100A because current cars can't take more than a 60A circuit can provide, and the new wall connectors will be more flexible in their power sharing when it's enabled.
 
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Even if you can fit 5 cars, you don't need more than 3 charging stations unless you have more than 3 drivers in the household that would all need to charge at the same time. You still need to do a load calculation to see if you can really provision 3 independent 60A circuits. There may be some other limitation upstream of that 200A panel. I don't know your overall topology, just that you have a two gateway Powerwall setup.

You can only use 6ga if it's THHN or equivalent in conduit. If you want to use Romex, you have to go to 4ga for 60A. IMHO, there's no need to go to 100A because current cars can't take more than a 60A circuit can provide, and the new wall connectors will be more flexible in their power sharing when it's enabled.
my two 200 feet 6/3 romex from my inverters to generation panel are 60 amp breakers so is this not okay for 60 amp ev chsrging.

yea 5 is nuts but again i try to plan for future nuts stuff. i miss some but ...
 
sounds like you ran 4 gauge wire to each connector.

I guess there is a balance between great and over kill. My 5 PW batteries are great, 7 would have been a total overkill.

Seems the great thing to do is run 6/3 wire with 60 amp breakers. Run these into a box wire with wire nuts for now, so I can get, when needed
the correct wall connector. Then I have to think is it better to run separate wires up my wall, or should I put another subpanel in my garage, so I only run one wire from the below subpanel. And then run the wiring from that. So many decisions. And then what size subpanel would I run since that wire gets big.
I would run a second conduit for control wires, in case you need it...
 
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I can't resist jumping in with a question about disconnects. But if you put a 100A circuit that contains EV chargers; would you need to put a disconnecting means within line of sight of the chargers under CEC 625.43? Or does that rule only care if an individual charger is 60.00001 A or above?

PS, I want H2ofun to go get a 9th disconnect.
 
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