Solar Panel Voc-MPPT?
Wondering if there is any relationship between measured Voc and MPPT performance with a 24v panel. My 12v panel has a Voc rating of 21.9 and Isc of 8.2, but I often see 8.2ish when Voc is only 20....
Forum Discussion
"The practical value of Voc and Isc is that you can measure them" That's about it. They are primarly used to match the controller specifications, not much else (Think Panel Power). All controllers have MAX input voltage ratings and current output ratings. MPPT is rated at Power in and current out - think POWER as in Watts
"Panel is rated Voc 37v and Isc 8.3a" these numbers can not be used to determine WATTS if you did you have a 307watt panel - "(Vmp is 30v and Imp is 7.7a)" these are good numbers a 231 Watt panel. Vmp is always lower than Voc - go back and take a look at your panel's IV curves, Voc current is Zero.
"The OP question is how can you do a similar thing with MPPT?" You will need to measure directly at the input side and the output side of the controller both voltage and current. If your Trimetric is connected to the battery "-" cable it's not reading the needed data.
Voltage / current graph shows the battery voltage to be almost constant
Vmp is the magic number that the MPPT determines by it's internal "TRACKING" alogrythm
"Battery Current" is actually LOAD Current NOT battery current
"Panel is rated Voc 37v and Isc 8.3a" these numbers can not be used to determine WATTS if you did you have a 307watt panel - "(Vmp is 30v and Imp is 7.7a)" these are good numbers a 231 Watt panel. Vmp is always lower than Voc - go back and take a look at your panel's IV curves, Voc current is Zero.
"The OP question is how can you do a similar thing with MPPT?" You will need to measure directly at the input side and the output side of the controller both voltage and current. If your Trimetric is connected to the battery "-" cable it's not reading the needed data.
Voltage / current graph shows the battery voltage to be almost constant
Vmp is the magic number that the MPPT determines by it's internal "TRACKING" alogrythm
"Battery Current" is actually LOAD Current NOT battery current
