This is a unique, open flow collector design which reduces cost while still providing high efficiency.
The collector pump is powered by its own PV panel and heats the pool without using any external power source. The collector price comes in at about one third of what commercial pool collectors cost.
At the bottom of the collector, the heated water is collected and routed back to the pool.
Matt's collector is about 64 sqft and does a good job of heatin his 26 ft diameter octagonal 4 ft deep pool in VT.
The total cost of the system was about $260 and the price per sqft of the the collector alone was only about $1.80 per sqft!
One very nice feature of the way Matt did this is the PV powered pump that circulates water to the collector. By having a separate pump for the collector, the main pool pump (which uses quite a bit of power) does not have to be run for solar collection. And, by using the PV powered pump, no external power is required for water circulation to the collector. Powering the pump by PV also means that no controller is required, as the PV panel only generates power for the pump when there is sun on the pool area.
All the details on Matt's low cost, PV powered solar pool heater...
This collector is in part based on this experiment I did a while back on an open flow design. The experiment includes measuring performance of the collector along with an estimate of efficiency and an explanation for why the collector performs well in spite of some heat loss due to evaporation from the open flow.
It is really nice to see this design working well on a real pool :)
Interestingly enough, this same collector configuration can also be used for cooling....
I'm in the process of trying a full scale cooling application using the Solar Shed as described in the link just above.
Gary