Pipe Sizing and Flow Rates

The most common mistake in applying solar pool heaters is to not take into account the overall pool design and the equipment being used.
The roof mounted systems require, in some cases, additional pumping power to move the water from the ground level, through the collector array, and back into the pool. 

Most often this is the case with two story roof applications. typically the use of oversize piping can eliminate this need in the case of single story residences, as the pool is usually plumbed in 1 1/2 inch PVC and most solar systems only require 25-50 GPM.
Competent pool designers understand the relationship between pipe sizing, flow rates, head pressures, and the appropriate pump and filter sizing to have a balanced efficient swimming pool design. 
When adding a solar system to a pool the overall flow parameters of the swimming pool must be considered when choosing the components of the solar system. There is nothing worse than taking a perfectly functional pool and to save a few dollars on the solar system, wind up with key elements of the pool not working or suffering reduced life spans.

Approximate Maximum Flow Rates

Schedule 40 PVC

Pipe Size / Inches

Flow Rate

Gallons
1 25 GPM
1.5 60 GPM
2 150 GPM