More MPPT Confusion and Question
Still trying to understand my MPPT set-up and what would be the effect of changing things a bit. My 230w (30.0 Vmp x 7.7 Imp) poly panel has a Vmp of 30.0v with a measurement tolerance of +/- 3% S...
Forum Discussion
It is possible the Isc is above rating when new.
I have had Sharp, Sun, and Hanwha panels (so far :) ) Their warranties are about not losing more than a certain amount over the years. Not to stay at as new ratings. The ratings you get when new are plus or minus already though.
A dealer told me that means when he gets a shipment of panels the average panel in the shipment of say 130w panels must be 130w, but any individual "130w" panel could be more or less that. Luck of the draw what yours might be out of the pile when you buy one.
It would be interesting to monitor Imp and see how that related to Isc, etc.
Mena is right that a clamp-on meter would be handy to get Imp if you can get at the wire. Do the fancy controllers display inputs as well as outputs? My controller only displays output.
If somebody here has that, please post some actual figures where we can see what Vmp and Imp are compared with output power. That would show the controller's actual efficiency.
To complete the picture also note the wattage of the array and wattage limit of the controller so we know where we should be on the efficiency curve.
Also be good to know at the same time as those figures are taken what the panel temperature is and ambient temperature, and the panel Isc and Voc at the moment and of course the panel's ratings as printed on it.
Throw in the voltage at the panel and at the controller input (should be near what the controller thinks the Vmp is but with line loss showing.)
With that info, we can compare it to what I got except for the Imp I don't have (except by assumption from the other figures). That should clear up whether my figures are "normal" too.
I have had Sharp, Sun, and Hanwha panels (so far :) ) Their warranties are about not losing more than a certain amount over the years. Not to stay at as new ratings. The ratings you get when new are plus or minus already though.
A dealer told me that means when he gets a shipment of panels the average panel in the shipment of say 130w panels must be 130w, but any individual "130w" panel could be more or less that. Luck of the draw what yours might be out of the pile when you buy one.
It would be interesting to monitor Imp and see how that related to Isc, etc.
Mena is right that a clamp-on meter would be handy to get Imp if you can get at the wire. Do the fancy controllers display inputs as well as outputs? My controller only displays output.
If somebody here has that, please post some actual figures where we can see what Vmp and Imp are compared with output power. That would show the controller's actual efficiency.
To complete the picture also note the wattage of the array and wattage limit of the controller so we know where we should be on the efficiency curve.
Also be good to know at the same time as those figures are taken what the panel temperature is and ambient temperature, and the panel Isc and Voc at the moment and of course the panel's ratings as printed on it.
Throw in the voltage at the panel and at the controller input (should be near what the controller thinks the Vmp is but with line loss showing.)
With that info, we can compare it to what I got except for the Imp I don't have (except by assumption from the other figures). That should clear up whether my figures are "normal" too.
