Barry The stated voltage is 18V and the max power is 280WThe formula as follows: P (power in Watts) = I (current in Ampere) x V (voltage in VoltsThus I = P divided by V=280W divided by 18V=15.55 Ampere (This is at max sunlight giving max rated watts)To use this with a PV controller to charge batteries you would need a solar controller that can handle 20A The average sunlight is South Africa is approximately 5.5 hours per day - you will need to Google the average sunlight per day in YOUR area.Thus if the average sunlight is 5.5 hours and the max power is 280W then Amp Hours works out to 15.55A x 5.5 hours - this is roughly 85 A hours - so this would be suitable to charge a 68 Amp Hour battery (75 percent of 85)

Barry What is missing? My unit seems to have everything as promised. The only thing I most probably will not use is the temp probe as you cannot submerge the thermo couple in water :(

Barry They put a sticker on the back of the unit - mine is 8Gb