I have an 2kW MPP Solar 2424LV inverter/charger and have been using it for over 2 years. 24 volt system with 2-350W Longi brand panels, in series (combined voltage around 80V), and one 24V, 200 amp-hour LiFePO4 battery. My only complaint is that regardless of my settings, the system never completely stops charging the battery from the panels (as long as the sun is shining, of course). It seems to “trickle charge” low amperage even after the battery is fully charged regardless of the settings for bulk charge, float charge, etc. When I originally put the system together and noted this, I found a topic on this forum that identified this as a “glitch” of the system. So, since it really caused no other problems for me I just ignored it.
Very recently I upgraded the system with the purchase of 2-550W Renogy brand panels. I made certain that the inverter could handle these panels, etc. I swapped out panels and the system was initially working fine. The panels were putting out about 1,100W as expected on a sunny day (also in series, generates around 99V). I ran a load on the system on a sunny day to put it to a test. After about a half hour, the system stopped and I got an error code “08”, “Bus voltage is too high.” As I was looking in my manual to find this code, the system came back on all by itself; however, the inverter kept shutting the panels off and then turning them back on every 30 – 60 seconds or so. I realized the reason why was because the battery was getting up to its overcharge cut off (30V). Once the battery got down to its charge restart voltage (28V), the panels came back on line, but 30 seconds later, voltage ramped up again and the process just repeated itself. I shut the load off, no change. I lowered the bulk charge voltage (29.2V down to 28.8V), no change. I tried lowering the charge amperage to battery (40V max down to 20V max). No change. Since I figured this wasn’t good for the battery, I switched off the panels.
I could think of nothing else to do, so I reluctantly swapped out the system with the old panels. I put the system back online and everything was fine. One note here, the smaller panels seem to charge the battery up to around 26.7V and it stays there even during the “trickle charge” mode.
One thing I find frustrating is that this model inverter does not have a setting that you could actually set yourself for maximum voltage for the battery where it would stop charging it. The 30V cutoff I noted above is what the battery’s BMS is set for (I have no way of changing this and wouldn’t want to). I have the charging time set to Auto. I can set that manually on the inverter but that is not going to help as far as I can see. I read on this forum that some people set a specified charge time when in a low voltage situation but, again, I don’t think that will help at all. Also, I’ve noted comments on this forum that this inverter is old enough that it has no specific LiFePO4 setting, just “user” which is what I set it at. So, to sum it up, the smaller panels don’t cause this problem but the larger ones do.
So, any suggestions? I’m assuming it’s the inverter.
Also, since I already purchased the panels and would like to keep them, I’m not opposed to getting another inverter if the other one is outdated. Any recommendations? I do not wish to upscale any further so would be looking at a 24V system.
Very recently I upgraded the system with the purchase of 2-550W Renogy brand panels. I made certain that the inverter could handle these panels, etc. I swapped out panels and the system was initially working fine. The panels were putting out about 1,100W as expected on a sunny day (also in series, generates around 99V). I ran a load on the system on a sunny day to put it to a test. After about a half hour, the system stopped and I got an error code “08”, “Bus voltage is too high.” As I was looking in my manual to find this code, the system came back on all by itself; however, the inverter kept shutting the panels off and then turning them back on every 30 – 60 seconds or so. I realized the reason why was because the battery was getting up to its overcharge cut off (30V). Once the battery got down to its charge restart voltage (28V), the panels came back on line, but 30 seconds later, voltage ramped up again and the process just repeated itself. I shut the load off, no change. I lowered the bulk charge voltage (29.2V down to 28.8V), no change. I tried lowering the charge amperage to battery (40V max down to 20V max). No change. Since I figured this wasn’t good for the battery, I switched off the panels.
I could think of nothing else to do, so I reluctantly swapped out the system with the old panels. I put the system back online and everything was fine. One note here, the smaller panels seem to charge the battery up to around 26.7V and it stays there even during the “trickle charge” mode.
One thing I find frustrating is that this model inverter does not have a setting that you could actually set yourself for maximum voltage for the battery where it would stop charging it. The 30V cutoff I noted above is what the battery’s BMS is set for (I have no way of changing this and wouldn’t want to). I have the charging time set to Auto. I can set that manually on the inverter but that is not going to help as far as I can see. I read on this forum that some people set a specified charge time when in a low voltage situation but, again, I don’t think that will help at all. Also, I’ve noted comments on this forum that this inverter is old enough that it has no specific LiFePO4 setting, just “user” which is what I set it at. So, to sum it up, the smaller panels don’t cause this problem but the larger ones do.
So, any suggestions? I’m assuming it’s the inverter.
Also, since I already purchased the panels and would like to keep them, I’m not opposed to getting another inverter if the other one is outdated. Any recommendations? I do not wish to upscale any further so would be looking at a 24V system.
