One solution to this is to fit a smaller dedicated solar pool pump in parallel with the existing filtration pump these pumps can be a tenth of the power of the filtration pump allowing for a great saving in operating costs.

When fitting the new pump you will need to install a non return valve in front of the existing filtration pump and in front of the new solar pool pump so that when either pump operates it does not drive the fluid back past the other pump and in the wrong direction.

Your new solar pool pump will be controlled by the Resol controller mounted on the Aztec Solar Water Heating pumping station backing board. Power will be supplied from the controller via a relay to the solar pool pump turning it on when required. Simultaneously power will be supplied from the controller to the flow switch.  This flow switch will then turn on the pump (this is a third pump used to drive around the solar system fluid from the heat exchanger to the solar water heating panel on the roof  and is not to be confused with the new pump that you have just fitted in parallel with the filtration pump).

The flow switch is fitted just in case the new solar pool pump that you have just fitted next to the filtration pump fails.  In this event the flow switch will turn off the solar system fluid pump and cool off the heat exchanger which will stop the empty plastic pipes from melting down.  Remember in this instance the new solar swimming pool pump has broken and there is no water in the plastic piping to take away the heat from the heat exchanger.

There is one more potential advantage in using a smaller powered solar pool pump which is that the flow rate of the water through the piping and in turn the heat exchanger is a lot slower and therefore should allow for a better transfer of heat from the exchanger and allow for better performance of the whole solar water heating system and potentially save you more money on the operating costs for your swimming pool.