@martinaddison EVs are 'credits' which are different than 'deductions' and are used on the tax forms in very different places. the EV credit has absolutely nothing to do with itemizing deductions.
here is the easy way to figure it out.
Look at Line 22 of form 1040, the EV and Solar credit can reduce this number to as low as zero, but no further.
The EV credit is 'use it or lose it', meaning you can use the credit to reduce Line 22 to zero in the year you purchase the EV, but if there is credit still left over, it is gone and lost forever. That is simply the way it works.
The Solar credit is NOT 'use it or lose it', meaning whatever you can use to reduce Line 22 to zero is great, and if there is credit still left over, you CAN use whatever is left over the next year or the next year or the next; it never expires
if you have both credits - the EV credit will get used first and then the Solar credit will get used.
