15 amps Vs. 30

[Hugh Mannity]

Adding solar to a house is an improvement to the house. You get the cost back if/when you sell the house. Do you expect to see a break even point if you add a room or a pool to a house? I installed solar in September of 2013. So far my panels have generated 71,800 kWh.
That's 71,800 kWh I didn't have to buy from the power company.

yeah that ^^ also some of us think of solar as the "right thing to do"; I'm honestly not too concerned with ROI on my solar system; I know I'm generating power independent of a mostly gas fired power grid in my area.

 

[beatle]

Back to the original topic, I don't think there is an appreciable difference between efficiencies when charging at different rates. I've experimented with 32A vs 40A at 240v, and the 32A is marginally more efficient, maybe by 1% - 2% or so. They are both in the low 90% efficiency ranges. 120V charges are significantly less efficient, usually in the low 70s. This is based on my charging data from TeslaFi.

I would not say upgrading your wiring is worth any potential efficiency gains. It can be nice to charge quickly on occasion (topping off before a trip, for example) but those would be fringe cases for me, and lower amperage would suffice for 99% of my charges.

 

[Jae001]

Good to know! I am working with 12 gauge wire right now and it is not safe for the amperage. If I am going to replace it I might as well go to 6 gauge to future proof the install. I really wanted to know if I was going to save electricity going to higher amperage on thicker wire but it looks like a 2% savings at best. Still worth it for a fast charge when needed.

 

[Big Toys]

6 gauge will work, 4 gauge is even better, as it will conduct 80A safely to about 15 ft, future-proofing your wire, and assuming your charger wire can handle that load. Feed it 220V from the box with the correct outlet and you are good to go with charge in half the time! IIR, I have 30A service at 220V, so I set my OpenEVSE charger to 25A max to protect the wires.

 

[Jae001]

I read that 4 gauge will not screw into a Nema 14-50 receptacle.

 

[Big Toys]

I read that 4 gauge will not screw into a Nema 14-50 receptacle.

Yeah, too thick. That's why I hedged with the "correct outlet". I do not know what connector to use for that wire.

 

[quickstrike12]

Are you finding that rate for a renewable energy source? I've not seen one that low which isn't almost 100% gas/coal generated.





You're probably right if this is a 100% financial decision for you. Buying a Tesla probably wasn't a sound decision financially, either.

LOL. Buying my Tesla was definitely not a sound financial decision. But again it’s DAMN FUN! After 2 years of ownership
Would do it again today without hesitation.
my electric rate is coming from a smaller provider using the Oncor lines. So no probably not using renewable energy sources.

 

[riles246]

I read that 4 gauge will not screw into a Nema 14-50 receptacle.

Just depends on which NEMA 14-50 receptacle you buy. The one I bought was stamped with "6ga CU 4ga AL", which makes sense since you need a thicker wire when using aluminum. But it reasons that one could just as easily put 4ga CU into the same receptacle.

 

[Big Toys]

Although you'll have the wire that can exceed it, be sure to stay below the rated amperage of the receptacle, I think it's about 20%.