MPP Solar LV2424

[Jameswy]

I just finished building a solar generator with an MPP SOLAR HVLV2424 inverter/charger. I am using (x8) 3.2V 280Ah lifePO4 cells with the Overkill Solar 100A 8s 24V BMS.

Everything seems to work until I plug the inverter into the grid (wall outlet). The input voltage shows 122VAC until I put any type of load on it and then both the input and output voltage drop to like 80VAC including when just the fans spin up a bit on the inverter. When it does this I noticed the BMS shows an over voltage warning as well. When I disconnect the grid power then the output voltage remains constant at 120VAC including when I add a load.

Attached is a images of the inverter during this operation as well as the BMS.

I tried to insert a recording but wasn’t able to do that to show it going from 122VAC to around 80VAC and then once the load is gone it jumps back up to 122VAC on both the input and output. Again it does this with only the load of the fans on the inverter.

 

[rodrick]

it sounds like a ats problem if solar and battery work ok and the outlet is good ( you can test the outlet with a heat gun and a kill a watt meter)

one other thing to look at is your charge rate maybe it needs to be adjusted try dropping it to 10 amps and see if it makes a difference is it possible that you are overloading the outlet?

 

[niktak11]

Not that this has anything to do with your issue, but to use the full current rating of your BMS you need to use both connections.

 

[OffGridInTheCity]

I have an MPP 3048LV in my trailer which I assume is similar. One time I ran 100ft of extension cord to it for AC input from a plug that was 150ft from the main panel causing a 250ft overall circuit and the voltage drop was significant - e.g. 120v -> 105v or something like that.

When I put the load on, the AC input at the MPP Solar dropped further to 95v (or something like that) and the MPP Solar stopped providing output. There is a low voltage AC input limit that will be in you're specs for the MPP 2424. Maybe you're seeing some combination of what I experienced?

The fix for me was to plug the 100ft extension cord into a socket right near the main panel and this bumped the incoming AC up to 115v so the drop was only to 110v under load.

 

[Jameswy]

Here is what I found hopefully this helps a bit with diagnosing.

Voltages at my wall without inverter plugged in:

Wall outlet:
Hot to Neutral 122 VAC
Hot to Ground 122 VAC
Neutral to Ground 0 VAC

Inverter plugged in and measured at inverter connection points with no load other than inverter fans:

Hot to Neutral 112 VAC
Hot to Ground 117 VAC
Neutral to Ground 5 VAC

I don’t know what that means is going on but it seems to only be with the inverter when plugged in. The voltage drops as soon as I hear the switch go on for the AC input.

I don’t believe there is supposed to be voltage between neutral and ground. I followed the installation instructions exactly and was wondering if the ground and neutral are supposed to be bonded internally but maybe it isn’t.

That is as far as I’ve gotten so far and I really appreciate any help.

 

[Jameswy]

it sounds like a ats problem if solar and battery work ok and the outlet is good ( you can test the outlet with a heat gun and a kill a watt meter)

one other thing to look at is your charge rate maybe it needs to be adjusted try dropping it to 10 amps and see if it makes a difference is it possible that you are overloading the outlet?

I did adjust the charging amp rate to 10 and it remained the same with the voltage drop.

 

[Jameswy]

Not that this has anything to do with your issue, but to use the full current rating of your BMS you need to use both connections.

I was wondering if that was critical and am planning to add a second connection. I was just setting it up to ensure things were working properly before I install it in a hard enclosure. Thanks for noticing that and making that point because I didn’t know if both connections were critical.

 

[rodrick]

I did adjust the charging amp rate to 10 and it remained the same with the voltage drop.

I’m back to thinking it’s in the ats bad connection, wired wrong, faulty board or sometching is it still under warranty? If so I would reach out to them and see what they say or contact mpp directly

 

[Jameswy]

I’m back to thinking it’s in the ats bad connection, wired wrong, faulty board or sometching is it still under warranty? If so I would reach out to them and see what they say or contact mpp directly

Unfortunately I don’t think it is. I bought it in 2021 and am just starting the project this week…talk about procrastination?

 

[Jameswy]

I’m back to thinking it’s in the ats bad connection, wired wrong, faulty board or sometching is it still under warranty? If so I would reach out to them and see what they say or contact mpp directly

Sorry I’m not super familiar with these terms. What is the ATS?

 

[rodrick]

automatic transfer switch its a relay that switches from different power sources