I think the construction on this parking lot is a new supercharger:
639 S Bernardo Ave
Sunnyvale, CA 94087
I found its permit here: https://sunnyvale.ca.gov/civicax/filebank/blobdload.aspx?blobid=23794
10/06/2020 2020-1278 13 RE$228,000 TESLA, INC 639 S BERNARDO AV BL EL FP INSTALLATION OF 16 NEW EV CHARGERS FOR **TESLA**
I assume “EV CHARGERS” means Supercharger?
I saw the fenced area and got suspicious that the layout looked like a supercharger. Then I found the permit via a Google search.
Here are two pictures from Nov 18:
View after turning into the lot: