I completely shut off my solar for the last 2 weeks to conserve eletricity while travelling and not using the pool.
I live a few miles from the beach and every night it cools down to the mid 50's regardless of the temps during the day and I returned to a pool sitting at a crisp 71 degrees.
We've had a heat wave in the last three days and I felt like swimming so I decided to see just exactly what I could get out of a 90 degree day so I RPM'ed up my epump to about 3100 RPM or 1300 watts just under the full 2 HP and let it rip as long as the solar tap called for heat.
I was able to get an ASTONISHING 15 degree rise out of the system in a single day.
The tap opened at 8:30 and closed around 4: 30 even though the panels were shaded starting about 4.
This computes to an astounding 2,502,000 btus delivered to the water in a single 8 hour day or just shy 313K btu per hour on average.
This is performance just a bit below what my 400K btu natural gas heater can achieve at the cost of around 5-6 dollars an hour.
I estimate the electricity cost was 1.56 cents to do this based on .15 cents a KW hour.
This is nothing short of incredible in my mind to achieve this level of performance for this tiny amount of money.