Above Ground Pool plumbing for Solar Heater?

I have a Intex 18'x48" metal frame pool that has a Intex 635T (1500gph) filter pump and the Intex Saltwater generator system on it. I recently purchased a 2'x20' solar heater for it, and after installing it the provided hose and fittings, the saltwater generator now sets a "low-flow" alarm.
To verify, I unhooked the output hose from the solar heater going to the pool, and it is pumping, but not a large volume.
I then moved the solar heater to be the first in the system: 1)heater, 2)pump, 3)generator. It had no noticable change and the generator again set the alarm.

My opinion is that the pump is not big enough to pump thru the 2x20 array, but before I spend more money, I would like some opinions on what else I could try?

1. Plumbing arrangement: The pool liner has two orifices for plumbing, one is approximatly 6" higher than the other, but both are submerged. Currently I have the lower orifice as my suction, going to the pump, then to the generator, and finally thru the heater and back to the pool 6" higher. Is this the correct plumbing arrangement?

2. The heater came with fittings and hose that are 1-1/4" diameter, but my entire system is 1-1/2". If I was to switch this plumbing out to 1-1/2", would that correct my issues?

Bumping this back up to see if anyone can reply.

This may work. You should have pump, solar, swg. You need a ball valve to get more flow. From pump out add a t, obviously one end from pump, one end of t to solar, the other to a ball valve, from the ball valve, another t, one end from solar, the other to swg. You can now open the ball valve and bypass the solar a little to increase your flow.


pump
+--------to solar
ball valve
+---------from solar
swg

Dont know why im having trouble putting this into words, but it should work. When I use my solar, there is not enough flow for my auto vac, so i open the ball valve and the flow increases since im not diverting all the water through the solar panel.