Oh, they're definitely in series, but I think you are confusing numbers. Individual solar panels typically produce voltages in the 20-40V range. Stringing them together in series to get hundreds of volts is not only common but expected. You're probably thinking of 350 Watts from a single panel, which is typical for a new panel in 2023.
The only question here is how many series strings these panels are wired in. From the photos I eyeballed about 100 panels, so my guess is they are wiring in a handful of strings -- could be 3, could be 10. Maximum string voltage is 600V or 1000V, depending on Stuff.