I just had a question about the MPPT voltage for the solar grid ties. I was just wondering why the GTI runs at a higher voltage with just one. Could it be because I have 6ga 15 ft and 1/0 for 20 ft? All panels are in parallel and rated for 21 v open voltage.
I thought I would give it another test to see if adding some 12 ga wire to it would jump the voltage up. By the pictures the voltage went down and so did the watts. Not what I expected. You would think the voltage would go up to compensate for the resistance.
"I was just wondering why the GTI runs at a higher voltage with just one." "One" what? Can't tell what you are doing.
I always thought that MPPT was supposed to go for the higher voltage when tracking. From what I am getting I was wrong. By using just one GTI it is a bit higher. That was expected. But with some 12 ga added the voltage dropped. To me that is unexpected. You would think that the voltage would go higher not lower.
You mean you ran a seperate #12 in parallel with your existing wiring and were only using one GTI? I do know having 2 GTIs in parallel is like having 2 women in bed -- they don't put out equally and sometimes one just gives up!
I ran the 12 ga in series to up the resistance. I figured the voltage would be higher to make up for the added resistance. But instead the voltage went lower and output dropped. I expected some lower output but not the lower voltage. Just a reminder. I am just trying different things to see how the GTI reacts. I know some of the other MPPT circuits go for the highest voltage. Just thought the solar GTI would be the same. So if they go for the lower voltage then we better all be going for the biggest possible wire for the solar panels that we can afford. I know I am good. 2/3 of my run is 1/0 copper cable. The rest is 6ga for 580 watts from the solar panels.
Experimenting is good. I don't know exactly how these GTIs work but since the PV is the only voltage source, adding series resistance would lead to less voltage at the GTI in general. I believe the GTI plays with the load side (effectively adjusting the current) to see how the source (the PV panel) reacts. It compares the prior V x I to the current V x I and operates at the better of the 2 settings.
The more we can learn about these GTIs, the better informed we'll all be when it comes time to choose the right equipment for a given situation. Great job guys!
The first test was on the CPT-1000w Hybrid. Here are the pictures for the SunG 600w solar. This turns out to be another case why NOT to by a CPT-1000w and go with a SunG model. I do not know if all Hybrids are the same but this looks like more what I expected. Close to the same voltage not a lot lower. First one is with 12 gauge wire added. The second one without the 12 gauge wire.The yellow wire in the picture is the 12 gauge wire.
