240 outlet for 2022 leaf EVSE question

[SageBrush]

You don't have anything in your house that draws 15A or 20A yet your house is chock full of 15 and 20A breakers. You can have a 40, 50, 60, even 70A breaker on the right gauge wire running to your EVSE outlet to accommodate the Nissan EVSE.

Probably true, but there can be multiple outlets and lights on one breaker and using common wire

[LeftieBiker]

I think that using the example of general purpose circuits here is a bit inappropriate. Sure, most circuits are not designed to protect the device(s) for the reasons given. But with a specialized circuit like that for an EVSE, why not size the breaker to offer some protection for the device? The circuit has one device, and one device only, so why not make it do the best job it can: i.e. protect the wires and offer some protection for the device? After all, you don't see 50 amp dryer circuits, except in those few cases where you have a 30+ amp dryer.

[johnlocke]

I would genuinely appreciate an electrician explaining why the consensus is to run a new 50A circuit rather than to make use of the existing 30A circuit and an adjustable EVSE.

For many people living in a townhouse or an older home, a 100A main panel is standard. In such cases, the electrician will almost certainly want to upgrade the panel.

In contrast, using an existing 30A circuit, with a 24A limited EVSE, incurs no new wiring costs nor panel upgrades. It also allows the LEAF to charge at 87% of full L2 rate. Selling the Nissan supplied EVSE makes it a zero cost option...

I realize that cost isn't everything, but a $2000 unexpected bill (panel upgrade, wiring, labor, etc) for a new EV owner isn't fun and the pay back period isn't great either...

I see posts like this over and over again, so a sticky post by an electrician, covering the range of options, would be an excellent resource for future EV owners. It would also make it easier for MNL members to direct new members to the sticky post, like we do with LeftieBiker's excellent post.

I have a large house with almost all electric service (except for the gas stove and HVAC backup heater). That includes a 60A instantaneous water heater for the solar hat water backup. The main house is on a 100A service with another 100A subpanel for the spa. Even with all this, the most power I've ever pulled from the Mains is 20KW for 15 min. 83A at 240VAC A all totaled. Typically on a monthly basis, max loading is loading is around 10-13 KW with most of the time it being much lower. Most people grossly over estimate their power usage. think about what your average power usage is. Probably less than 2 KW. 100A Service is more than adequate for most homes even with a EV.

Most of the time panel upgrades are more about more breaker space or meeting a code requirement (adding PV to a 100A service could overload a 125A bus in an existing breaker box for instance). I recently upgraded a 100 amp outdoor panel to a 200A panel. The old panel was corroded and I wanted more spaces for breakers. The cost for a 200A panel instead of a 100A panel was less than $50 difference. I also replaced all the old breakers with new ones just because they were 30 years old. The panel is still fed by a 100A breaker This new panel feeds the house, garage, utility sheds, pond pumps and my EV charger all on a 100 amp service.

[SageBrush]

I have a large house with almost all electric service (except for the gas stove and HVAC backup heater). That includes a 60A instantaneous water heater for the solar hat water backup. The main house is on a 100A service with another 100A subpanel for the spa.
...
I recently upgraded a 100 amp outdoor panel to a 200A panel. The panel is still fed by a 100A breaker This new panel feeds the house, garage, utility sheds, pond pumps and my EV charger all on a 100 amp service.

I'm interested in how this all is wired. Could you start from the utilitie's meter(s) and explain how each panel is fed/connected ?

[johnlocke]

I have a large house with almost all electric service (except for the gas stove and HVAC backup heater). That includes a 60A instantaneous water heater for the solar hat water backup. The main house is on a 100A service with another 100A subpanel for the spa.
...
I recently upgraded a 100 amp outdoor panel to a 200A panel. The panel is still fed by a 100A breaker This new panel feeds the house, garage, utility sheds, pond pumps and my EV charger all on a 100 amp service.

I'm interested in how this all is wired. Could you start from the utilitie's meter(s) and explain how each panel is fed/connected ?

It's complicated. At the meter I have a 200A pedestal mount panel (required by SDG&E) that feeds 2 100 amp subpanels and the 60A water heater. The first sub panel is actually my battery backup system and a 9KW PV array. That feeds a 100A automatic transfer switch for the 20KW backup propane generator which in turn feeds the 200A subpanel for the house, outbuildings, L2 charging station, a second 9KW PV array, and the pond equipment. Even though the panel is rated for 200A it is fed though the 100A transfer switch. The PV array has a max theoretical 32A current so that subpanel could have as much as 132A on the bus. Never happens in practice but meets code requirements. The second subpanel is just for my hot tub and low voltage lighting. I may get around to adding a charging station to it in the future.

There additional subpanels in the house and in most of the outbuildings. Point is that I've got a lot of stuff and live on a 5 acre farm with a well and septic. I use nearly 30,000 KWH annually and have never come close to 100A draw. Most people use less than 1/3 of what I do.

[SageBrush]

^^ Wow

That maps out like a small industrial plant
Sounds nifty !
Thanks for sharing.

Out of curiosity -- when you say you use 30k kWh a year, is that the net consumption from the utility despite your 18 kWh of PV ?

[johnlocke]

^^ Wow

That maps out like a small industrial plant
Sounds nifty !
Thanks for sharing.

Out of curiosity -- when you say you use 30k kWh a year, is that the net consumption from the utility despite your 18 kWh of PV ?

That's total consumption. PV provides about 90-95% of the power I use. Most of the SDG&E consumption is in Dec-Jan. With the new battery backup system I only use SDG&E between midnight and 9AM unless the weather is bad. I am on net metering but SDG&E keeps trying to get rid of it. If they succeed in that, I'll have to consider adding another 8-9KW of PV so I can be 100% solar even in Dec-Jan. I really only need 2K more to cover my current shortfall overall but to cover Nov though Feb without any power From SDG&E requires a 9KW array due to short days and bad weather. If SDG&E changes their rate structure to only pay me wholesale rates for power I input and retail for power I pull back out, then I might find it cheaper to install more PV rather than pay them.

[goldbrick]

Since we're way off topic here already.....are your panels ground mount? Are the ponds used for hydro power at all?

I ask because I'm thinking of buying my dad's farm and going 100% PV. I'll ground mount the panels but haven't decided on whether to grid-tie, use batteries or try to do micro-hydro and I'm always interested in other's solutions.

I see you also like sub-panels. I have one now and am planning to install 2 more this summer. They make wiring so much easier in many ways and the cost is negligible and well worth the cost IMHO.

[SageBrush]

^^ Awesome.

Interesting to hear that you can cover your winter shortfall by adding only more kW and not having to also add more storage.
I doubt many people can say the same

[dmacarthur]

I have panel banks connected to battery storage and panel banks connected to grid-tie, and am always interested in the net power generated and sold to the power grid...... as I see it now the grid-tie is more efficient because it sells all produced power back into the grid, whereas the battery system has 2 inefficiencies: the batteries themselves are not 100% either charging or releasing, and the inverter which governs the battery system does not immediately sell the power back into the grid when the batteries are full. This latter issue actually makes a fairly big difference because the battery bank gets charged, the inverter takes a bit of time to switch over to grid sell, the batteries get drawn down a bit selling, it takes a few moments to switch back to charge mode, etc. I could probably fine tune all of this but the point is to use the batteries not simply keep them charged. Bottom line: grid-tie is more efficient, batteries give us more security for when power is out (which is not often, so....)