More advanced solar control systems, such as the SolarTouch from Pentair, offer precise control of your pool heating temperatures while also controlling the speeds of your variable speed pool pump.
When your solar pool heating system switches on, the control system will ramp up the speeds of your pump to the ideal heating flow rate. When the solar shuts off, the controls reduce the flow to conserve energy.
In the summer, when your pool needs cooling off, the control system can work in reverse, turning the system on at night and bringing pool temperatures down to more comfortable levels. The same function can be used in the winter to prevent solar panels from freezing.