Over the weekend we have almost perfect sun shine. So I collected some data on a 20 Tube solar collector. Here are the results.

Temp in | Temp out | difference |

33.6 | 37.6 | 4 |

The pump rate was at 6 liters per minute (0.1 liters second). So give this its possible to work out how much of the suns energy was being captured. We just need to know one more thing. The specific heat capacity of water. Which is 4.2 Kj / Kg / degree C. That is 4.2 kilo Jules per kilogram per degree C.

So the calculation turns out to be.

Total Energy per second = (Specific heat capacity of water) x (Liters per second) x (Temperature difference)

1.68 kW = 4.2 * 0.1 * 4