solar collectors

[Troytempest]

I know how solar collectors work, but how would you measure the energy output of one. Would it be possible to take the differences in temperature of the water running through it? Any help would be much appreciated.

[Teddio]

Heat Energy supplied by the Sun = Heat Energy supplied to the water.
Heat (Joules) = Mass of water (kg) X Temperature Difference (C) X Specific Heat Capacity of the water (4200J/kg/C)
If this is measured per second then the Power output in Watts is given.

[Troytempest]

cheers Ted