JazzRVwSolar
New Member
We have two 100/20 MPPTs dedicated to two 375W LG Panels. In other words, each panel has a dedicated MPPT. Also in the system is a custom 6S battery with nominal high voltage for around 24ish volts. We operate between low of 20 and high of 24. There is an inverter as well in the system. We are not seeing the expected production.
A solar tester was use to verify that the panels are meeting spec. They appear to be. Even called manufacturer to confirm the numbers the tester was saying because it was a bit lower than rated. However, their explanation was plausible and within limits of the solar tester. At mid day, the tester was showing 350W at the point where the wire feeds the MPPT. This accounts for any line loss from panel to MPPT. (In fact, this how we discovered that 8AWG wire was not 8AWG but 10AWG). But that discounted, the MPPT is still not performing any where close to the tested 330 - 350W.
On the other hand both MPPTs are way under performing what the solar tester shows. Instead of getting the 350W - 330W, the tester says (tested using the same wire that is going into the MPPTs), the two Victron MPPTs always max out at 290W (each).
At first, we though there was some kind of load balance going on or some kind of interference between the two MPPTs. We removed one MPPT out of the system. And ran everything with just one Solar and one MPPT. Same thing. The MPPT is maxing out at 290W.
Upon checking the specs and manuals, I noticed that the max rating for one of these (100/20) is 290W. I also noticed that this was for a 14.5V battery, which Victron calls 12V. And what Victron calls 24V specs is actually for a 29V battery. Thus the 24V of our battery falls far short of the Victron expecting a 29V, as their nominal 24V.
Our thinking now is that the MPPT despite being told behave as 24, is still going with 12V and limiting to max of 290W. The gap between 29V and 24V is too big for the Victorn 100/20. So, it is automatically downshifting to 12V (14.5V) and limiting to 290W max.
Any flaws or alternatives? Has anyone encountered this? What solution?
A solar tester was use to verify that the panels are meeting spec. They appear to be. Even called manufacturer to confirm the numbers the tester was saying because it was a bit lower than rated. However, their explanation was plausible and within limits of the solar tester. At mid day, the tester was showing 350W at the point where the wire feeds the MPPT. This accounts for any line loss from panel to MPPT. (In fact, this how we discovered that 8AWG wire was not 8AWG but 10AWG). But that discounted, the MPPT is still not performing any where close to the tested 330 - 350W.
On the other hand both MPPTs are way under performing what the solar tester shows. Instead of getting the 350W - 330W, the tester says (tested using the same wire that is going into the MPPTs), the two Victron MPPTs always max out at 290W (each).
At first, we though there was some kind of load balance going on or some kind of interference between the two MPPTs. We removed one MPPT out of the system. And ran everything with just one Solar and one MPPT. Same thing. The MPPT is maxing out at 290W.
Upon checking the specs and manuals, I noticed that the max rating for one of these (100/20) is 290W. I also noticed that this was for a 14.5V battery, which Victron calls 12V. And what Victron calls 24V specs is actually for a 29V battery. Thus the 24V of our battery falls far short of the Victron expecting a 29V, as their nominal 24V.
Our thinking now is that the MPPT despite being told behave as 24, is still going with 12V and limiting to max of 290W. The gap between 29V and 24V is too big for the Victorn 100/20. So, it is automatically downshifting to 12V (14.5V) and limiting to 290W max.
Any flaws or alternatives? Has anyone encountered this? What solution?
