You can view the Trico replacement wiper selection catalog at:
Entire your model and year, and the proper sizes will be displayed. For S80, driver side length is 24"; passenger side is 22".
The Volvo replacement blades (refills) are very expensive and I found them to be of poor quality. Unfortunately, they are a special width and aftermarket blades will not fit unless you replace the entire wiper (holder and blade). The good news is that a set or replacement wipers from Trico is less than half of the cost for Volvo refills. I paid $15 each for "exact fit" #22-9 (passenger) and #24-9 (driver). Replacing the factory holders took 15 minutes. Now I can buy replacement refills for less than $3 each, and they are easy to find.
The Trico holders do not have the plastic "spoiler" on the driver's side to increase downforce at high speeds. But I cannot detect any difference in performance at 75mph, which is the fastest speed I ever travel.