Rooftop solar thermal panel layout

[portero23]

Hey guys,
When setting up a bank of solar panels, how important is it to have the inflow and outflow come in and out of the solar panels on opposite sides, as opposed to inflow going in and outflow coming out on the same side? I realize there's some efficiency loss and slower flow through the far end of the system, but is it actually that significant?

See what I'm talking about below.

Inflow and outflow attached to system on the same side:



Versus outflow coming out way on the other side and then a really long pipe across the top bringing it back to the pool equipment like so:

 

[mas985]

It depends on the number of panels, panel size and the size of the headers. Here is the flow rate ratio for 4'x10' panels with 2" headers vs number of panels:



Plus panel efficiency is a function of flow rate (single panel):

 

[portero23]

This is really helpful, thanks for the info!