SunEarth manufactures all copper pool and spa heating collectors under the tradename of Oasis.  The Oasis pool collectors have standard 1.5" headers.

Oasis Pool Panel Specifications

SunEarth Model Number	Gross Area  (sq ft)	Dry Weight  (lbs)	Fluid Capacity (US gal)	Design Flow (GPM)	ΔP at Design (psig)	Max Flow   (GPM)	Max Pressure  (psig)	Header Width  (in)	Header Center to Center  (in)
OP-32	30.18	33	1.3	3.2	0.018	12	160	45 1/4	93 3/4
OP-40	37.19	39	1.5	4.0	0.020	12	160	45 1/4	115 7/8
OP-48	45.33	48	1.7	4.8	0.022	12	160	45 1/4	142 5/8

FSEC Performance Ratings

Oasis Specification Sheet