Al,

thanks for your thoughts.

I FINALLY got a couple of rainless days, and got the system hooked up last night and was able to give it a test run before dark.

When I fully closed the bypass valve, my pressure only increased by 2psi. That didn't seem like a very big jump. I had contacted the solar panel company, who said if the rise in pressure was greater that 8psi from normal operating pressure, it would be hard on the pump.

SO, still not sure about how to get the 1-4gpm optimal flow.

1 thing I thought about doing was opening the return line from the solar panel and putting a 5gal bucket under it. Turn on the pump and pump water for 1 minute and measure how much water was pumped out of the panels. This should probably work, shouldn't it?? Then if I am over the 1-4gpm, just close the bypass valve about 1/2way and do the test again. Sound like a plan??