To Charge or not to charge- that is my question

None of that is known to apply to the OP in New Jersey. NJ appears to have a very consumer-friendly net metering system, with production back into the grid credited at full retail price.

 

My information may be specific to Austin, and is second-hand. However, it’s probably fair to say that net-metering, and grid-tying, a system are not synonymous.

Grid-tying just means that you use power from the utility when you system isn’t producing power, and sell power to the utility when you have surplus.

Net metering, as far as I know at least, means that the utility tallies up your total usage and charges you, or pays you, for the entire sum usage, positive or negative.

As I understand it, at least here in Austin, all systems that they subsidize the purchase of (and possibly all systems they allow to be grid-tied; not sure) are grid-tied but not net metered. In return for subsidizing the cost of your system, they pay you less than they charge you. They then offer all in most of their service area a “Green Choice” energy option, which is partly powered from nearby solar.

Anyway, if the OP’s system is not only grid-tied, but also net-metered as I understand it, then, true, it wouldn’t matter.

 

OK, this is where the difference lies. Austin doesn't use a standard simple net metering system, but instead created something called VOST, which I haven't adequately digested yet:
How Does Austin Energy Net Metering Work in 2019? | EnergySage

In fact, they aren't even the same topic. One refers to the electrical and physical architecture, while the other refers to the financial aspect of energy exchange.

Grid-tie is simply the opposite of off-grid. The former is electrically connected to the local utility grid, the other is disconnected and isolated. The term says nothing about how energy is bought or sold.

Net metering is just one of several methods of buying and selling energy between the utility and the grid-tied customer/home-energy-producer. It is generally used in the most PV-friendly areas, while hostile areas generally have other systems. While Austin's system is derived from net metering, apparently the VOST variation makes it different than the common basic net metering systems used in many other places.

 

I know, my point was only that one can't generalize with regard to net metering, there are many different systems.

 

The other systems are not simple or basic net metering.

 

In short, grid-tying a system doesn’t necessarily imply that it uses net-metering, nor any other particular billing system.

 

But even if your solar can't keep up with the demand including charging the car, wouldn't you still want to pull from the grid to charge the car and not run the car on gas?

 

I personally agree that there are other, equally-good reasons, not related to finances, to drive on electric, such as reduced pollution and noise, both for you and the people and other creatures around you. Better responsiveness too.

However, just for the record, I gather the OP’s concern is not with the capacity of their home-solar, but with the economics of using that power directly vs. selling to the utility.

 

I was looking at the 100% green line. But, if the cost to run the car on electric exceeds the cost to run on gas, it's a more complicated decision.

 

I think the OP will find that his wife is incorrect about how much the electric company is paying for their electricity.

 

Base on today's price,
EV 25 miles need, 6.5 kWh x $0.18/kWh = $1.17
HV 25 miles need, 25 / (59 mpg) x $2.74/g = $1.16

 

For me right now, EV 25 miles need 6.3 kWh x $0.28/kWh = $1.76
HV 25 miles need, 25 / (55 mpg) x $3.74/g = $1.70

My electricity price is 22c for tier 1, and 28c for charging vehicle since I used all tier 1 quota. Fortunately I have solar installed.

 

EV 25 miles need, 6.5 kWh x $0.17/kWh = $1.105
HV 25 miles need, 25 / (59 mpg) x $2.89/g = $1.225
But like Roy, my actual electric cost is $0.0 since my solar array produces more than the house uses.

 

Are there no costs of the solar arrays that are being recaptured?

 

He is probably counting that as a sunk cost.

 

Yep. I've paid for them and they are generating more than the house uses. Our net meter credits expire a year from the month they are accrued. The capital cost per kWh generated/used is the same whether I put some in my car or give the utility free electricity. Some places will pay real cash money for excess net metering credits. In that case there would be an opportunity cost to using the extra in the car.