This is interesting, as you must be on the EV time of use rate from NV Energy. As I await the delivery of my MME, I have considered utilizing this plan once the car does arrive. However, I also had rooftop solar installed last month and the project advisor mentioned that his big thing is people are using solar energy incorrectly. He thinks you should use energy during the day as much as possible to utilize the energy being produced by the system first, before it gets sent back to the grid. His reasoning being that for each kWh you send back to the grid, your net metering credit is about 70% of the cost of buying that kWh back when you're underproducing your usage. This isn't the forum for it, but that sounded wrong to me, because the power company isn't looking at the time I used my generated energy, instead they are looking at the difference between what I consumed and produced for the entire month (at least I think that's how it works).I average 500 +/- miles a month and my driving miles per kWh is in the 3's so for easy math 500/3 = 167 kWh per month usage at 0.049 cents per kW off-peak 2200hrs to 0800hrs and all weekend, which adds $8.18 to my bill and a cost per mile of 1.6 Cents. The power company incentive with proof of an EV drops the off-peak rate for the entire house.
PS: I'm still on my first cup of coffee so if there are any Math majors reading this feel free to challenge my calculations.
Anyway, for the original poster, that just sounds wrong altogether. As others have said, you need to look at the usage for that exact month with EV compared to the prior year without EV. Also realize that the weather is warming up in March, which means you are naturally going to start to use more energy in your home in March as compared to February (with or without an EV). Another thing that you are already aware of, but with a tiered system like yours, you're already building in a 25% price increase to every kWh over 1,000 for the month. So if in February you used 985 kWh and then in March you went to 1,333 kwh, you had a 33% increase in usage which gets compounded by the fact that you had a 25% increase in cost for almost everyone of those kWh.
You didn't share your usage for the prior month, and you didn't give us context as to how much you drive and how much kWh you required to recharge your vehicle for the month. Every situation is different, so context is important