First, correct some math on the EV circuit
EVs are deemed continuous loads and need a 125% derate as a result. Thus you get assuming 240V:
- 15A breaker = 12A actual = 2.9 kW = 75-90 miles in 10 hours
- 20A breaker = 16A actual = 3.8 kW = 100-120 miles in 10 hours
- 30A breaker = 24A actual = 5.7 kW = 150-180 miles in 10 hours
- 40A breaker = 30A actual* = 7.2 kW = 190-225 miles - a very few EVSEs such as Siemens Versicharge are actual 30A, wasting a few amps on the 40A breaker. (Pointy Haired Boss?)
- 40A breaker = 32A actual = 7.7kW = 200-250 miles in 10 hours (gosh!)
Speeds above this are just bonkers. Most people grossly overestimate how much power they really need, and/or get swept into "50-amp thinking" because of a certain misconception.
ClipperCreek does not make a "30A actual/40A breaker" EVSE. The HCS-40 is 32A.
Charging 200 miles a night doesn't make any sense
The typical lease is 12,000 miles a year. If you only drive 250 workdays a year, that is 48 miles a day. Needing 200-250 miles of charge in a day is rather silly, and paying a fortune for a service upgrade simply to achieve that is even sillier.
Your EVSE would be 2 amps larger than Alec's from the video, and review this again. Alec is in Chicago and has been driving EVs for 8 years. I didn't cue up this part, but elsewhere Alec talks about having a 50A outlet and being able to run a 50A EVSE but simply sees no point.
Let's fix the Load Calculation too.
You made one critical error in the Load Calc here. You took all equipment associated with "Heating, Ventilation and Air Conditioning" and dogpiled them into HVAC. That's not how it works. You must actually do THREE sub-calcs for HVAC load, as follows:
- Load when the system is in A/C cooling mode.
- Load when the system is in heating mode normally.
- Load when in heating mode, heat pumps have failed due to temp below minimums, and Emergency Heat has come on. (better heat pumps do not require this).
You then select the one largest number of the three, and that's the one you carry onward into the Load Calculation.
Now typically, the EVSE's are advertised as the breaker value and then their true charge rate is 80% of that. ClipperCreek is no exception. They don't make a "30A actual, 40A breaker" EVSE. This is flat wrong for a Clipper Creek HCS-40.
EVSE NPR 30A @240V: 7,200
I do note that your Load Calc does work with the fake 30A number and doesn't work with the true 32A number. This leads me to a certain skepticism.
Unfortunately, Clipper Creek units deny you any way to jumper to different ampacities, otherwise I'd say "jumper to 24A and don't worry about it". Not a fan of the brand because of that. Honestly given your load calc and the fact that you could get a 16A or 24A unit in there with room to spare, I would have recommended a smaller unit instead of a service upgrade. Doing unnecessary service upgrades is practically the #1 blunder made by novice EVers.
Honestly you may be better researching Federal, state and local incentives for wall-unit installations, and see if you aren't money-ahead selling the HCS-40 on Craigslist and then buying the right unit with pro installation with incentives.
I'm sorry you made a purchasing mistake but it seems like you're going to extremes to try to salvage it. Just write it off as tuition from the school of hard knocks: don't impulse-buy technical products.
Level 1 vs Level 2 charging
I hear you in comments hating on level 1 charging, but don't create a "false dichotomy" where the only other option is your already-bought 32A (7.7 kW) unit. This is more "trying to rationalize the purchase".
In the US, we assume all 240V units get the circuit to themselves, and run at the "continuous load" 80% limit. As such they are more powerful than European units sized to share the circuit, and are properly called "Level 2". Even the smallest 15A/240V circuit (2.9 kW actual) does alright, as the earlier chart shows.
You are correct that level 1 is hurt by winter due to the "parasitic load" of keeping the battery heated sufficient for charging. However this is a fixed cost and if you increase power, all additional power goes to the battery. Thus even a 15A level 2 circuit, at 2.9 kW, isn't bad. By 20A (3.8 kW), the portion lost to heating the pack is negligible.
The charger is on the car. The EVSE is simply a "smart GFCI" and a tone generator to tell the EV's onboard charger how many amps it can draw. As such, many EVSE's are field-programmable to set the amps.
Most cars come with a free small travel unit, intended for opportunity charging "on the road". They provide dongle plugs for sockets found "on the road" - the standard one and the huge RV socket found at RV parks. This is the misconception. That travel unit runs 32A with that RV dongle, because the socket is also used on 40A circuits. However, vendors will sell you OTHER dongle plugs and those dongle plugs will command the car to use an appropriate ampacity. The dongles have a microchip in the plug, which also senses "hot plug" (this is a UL requirement). The microchip, since it's signaling allowed ampacity anyway, is able to reduce ampacity when it detects hot plug.
What I would do
I don't like unnecessary service upgrades. It's obvious that your house is slowly transitioning away from inefficient A/C units and to highly efficient heat pumps one section at a time. I expect that to continue, your service needs to decline going forward, and upcoming smart-breaker tech will only make it easier to fit stuff on limited services. Yours is a good example of a house that may never need a service upgrade.
Mind you, I am not burdened with an emotional need to salvage an unfortunate purchase.
So my winter configuration for your house would be to disconnect the A/C entirely - pull the wires off the breaker. It is now off the Load Calculation. If I could get a wall unit EVSE that is jumperable for different ampacities immediately I'd just do that, otherwise I'd get a 30A dongle for your travel unit, and wire a circuit to power it.
"30A" (actual 24A) charge rate should ease your winter charging anxiety.
By spring, I'd reconnect the old A/C and jumper the EVSE down to 20A. Shouldn't be a problem, just keep an eye on it. If it is, DC fast charging can always cover the gap for those "but sometimes" moments. The next fall, I'd try leaving it at 20A and see if 20A winter charge is sufficient. I bet it is.