Solar Systems- 2" vs 1 1/2" Header?

[CallMeIshmael]

Thanks so much for the tips!
Peter, my case was exactly like tphaggerty's. The contractor said "Unless there's a specific need for 2", we'll be doing 1 1/2" pipe on the return end." So I was just sizing up that need. It looks like 1 1/2" should be ok, since we'll have at most 6-8 panels with good sun. 2" pipe may be overkill for our size pool/panels, but might come in handy if we choose to divert return water to a water feature (a growing interest as we re-design things!), which would also run during daylight hours.
I think we need to take some time to digest this info here & all else we've received so far & go back to the design table for a few days. This is really helpful, so thanks for taking the time!

[CallMeIshmael]

An update: We've decided to go with 2" pipes throughout, both for solar as well as suction & pressure sides. In addition, we were able to find a local seller for 2" Fafco solar panels. The contractor agrees that it might be a bit of overkill on the pipe size, but that the improved flow rates should make several aspects of the pool run more efficiently (faster turn-over, better heating, better filtering), especially with a 2-speed pump.
Thanks again for the input!