EG4 3000EHV-48 - PV Voltage Drops from 240V to Exactly 120V

[matredd]

Hello everyone! I'm new to the forum and still learning a lot.

I built a mobile cart with the following
- EG4 3000EHV-48
- 2x EG4 LifePower4 48V 100AH Server Rack Batteries in parallel
- 6x 310W used REC solar panels from SanTan (have a pallet of 22 but only using 6 in initial tests)

AC charging and inverter output all seem to be working well.

I tested PV input for the first time yesterday. 6x 310W panels wired in series. They're in an area that is partially shaded. I'm using 35ft of 10GA wire. My multimeter shows around 250V before connecting the series array to the EG4 3000EHV-48. When first connected, the 3000EHV-48 also picks up around 250V but after it begins to use the panels (10-20 seconds in), the voltage drops to 120v. While observing the PV input voltage on the 3000EHV-48, it seems like the voltage begins to climb up a bit to around 150-160 and then the voltage immediately drops to 120v. As I understand it, 120v is the minimum PV input voltage for this inverter.

The wattage generated varied with the shade (obviously). I saw as high as 600+ watts for a moment but most of the day, it was only around 80-120 watts. I'm wondering if the low wattage is due to the voltage drop? These panels are temporarily placed on the ground. Right now, I'm just testing to determine the ideal location.

Any input/advice would be much appreciated. I'm still searching the threads for a similar experience. Hopefully it's something simple!

 

[pvgirl]

If any of the panels in series are partially shaded that will limit your output. The voltage changes are due to the inverter trying to find the maximum power point, and putting a load on the panels.

 

[matredd]

Ok. I was curious how much it had to do with inverter load and shade. I'm going to test by doing a couple strings of 4 or 5 panels in series parallel to see if that helps. Thanks!

 

[AZ Solar Junkie]

Ok. I was curious how much it had to do with inverter load and shade. I'm going to test by doing a couple strings of 4 or 5 panels in series parallel to see if that helps. Thanks!

I'm using the Tigo TS4-A-O optimizers on my panels which are helping tremendously to avoid shaded panels from impacting (as much) the total output of a series string. They allow current to bypass a shaded panel that would otherwise be limiting the current flow through the string...

 

[k490]

I'm using the Tigo TS4-A-O optimizers on my panels which are helping tremendously to avoid shaded panels from impacting (as much) the total output of a series string. They allow current to bypass a shaded panel that would otherwise be limiting the current flow through the string...

I saw this video says optimizers aren't worth the extra money the built in diodes that all solar panels already have bypass the current when shaded. How much better wattage did you get out of them after installing them? I'm going to be upgrading my system soon neighbor's trees do shade in the late afternoon.

 

[DIYPV]

If any of the panels in series are partially shaded that will limit your output. The voltage changes are due to the inverter trying to find the maximum power point, and putting a load on the panels.

I’m having shading issues and have seen the current drop from 6.5A to 0.5A while the voltage increase at the same time from 300V to 360V.

The shading is very minimal and covers the the entire width of the panel, but only 4” high. This is should cut all strings of cells on the panel.

Should the panel’s bypass diodes allow current to flow while voltage decreases on the series string without the shaded panel?

Is the MPPT doing something to increase voltage?

 

[AZ Solar Junkie]

I saw this video says optimizers aren't worth the extra money the built in diodes that all solar panels already have bypass the current when shaded. How much better wattage did you get out of them after installing them? I'm going to be upgrading my system soon neighbor's trees do shade in the late afternoon.

For me, they increase production about 12%

 

[EG4_Jared]

I’m having shading issues and have seen the current drop from 6.5A to 0.5A while the voltage increase at the same time from 300V to 360V.

The shading is very minimal and covers the the entire width of the panel, but only 4” high. This is should cut all strings of cells on the panel.

Should the panel’s bypass diodes allow current to flow while voltage decreases on the series string without the shaded panel?

Is the MPPT doing something to increase voltage?

As current decreases with shading, you can see voltage increase. The best way to minimize the shading would be to add optimizers.

 

[DIYPV]

As current decreases with shading, you can see voltage increase. The best way to minimize the shading would be to add optimizers.

I’ve tried to disconnect that single panel and have produced more daily power without it.

I guess I’ll eliminate that panel from the string for now or possibly buy one optimizer for this problem panel.

 

[k490]

For me, they increase production about 12%

Might be cheaper to just add couple of extra panels for the cost. I suppose it's nice to have for panel monitoring, and if Rapid shutdown is required might as well spend few extra bucks and get the optimizers.

 

[AZ Solar Junkie]

Might be cheaper to just add couple of extra panels for the cost. I suppose it's nice to have for panel monitoring, and if Rapid shutdown is required might as well spend few extra bucks and get the optimizers.

I hear you. My brother is a firefighter and I really believe in protecting the first responders with the rapid shutdown button out by the main panel. The bit of extra power and panel level monitoring are just nice bonuses to me.