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Fluctuating DC Current on Axpert 5Kva?


Hennie Lange
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Hi, wonder if you can help.

I have an Axpert 5KW 48V inverter with  with 9 x 270W PV connected in an array of 3strings with 3 panels in each string.

I measured each string, got 107V with 7~8A per string.

But measuring the leads connected to the inverter there is 107V.

But the Amps reading on the inverter is intermittent, jumping from 0A to 6A.

Can you shed some light on this.

Not sure what other tests I can do.

It almost looks like there might be a problem with the Inverter PV controller.

Pleas advise.

 

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15 hours ago, Hennie Lange said:

But the Amps reading on the inverter is intermittent, jumping from 0A to 6A.

Remember that the PV current is always battery-side current, not panel current.

In some models, it's net current into the battery; for others, it is total charge current (sometimes there is a screen for both).

I'd say you are seeing net charge current (factory firmware treats discharge as a separate current, so this never goes negative). So it is probably just that at times you have ~ 6 A x 50 V = 300 W more PV power than load power (ignoring losses).

To figure out what the panels are doing (from the inverter), use the PV power screen. It's always total PV power (never net). It should be around 107 V x 7-8 A x 3 ≅ 2250 - 2500 W. 

Edited by Coulomb
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On 2020/08/01 at 11:47 AM, Hennie Lange said:

Hi, wonder if you can help.

I have an Axpert 5KW 48V inverter with  with 9 x 270W PV connected in an array of 3strings with 3 panels in each string.

I measured each string, got 107V with 7~8A per string.

But measuring the leads connected to the inverter there is 107V.

But the Amps reading on the inverter is intermittent, jumping from 0A to 6A.

Can you shed some light on this.

Not sure what other tests I can do.

It almost looks like there might be a problem with the Inverter PV controller.

Pleas advise.

 

Hi Guys

I have the same issue here. Did you sort this problem out? Is it just a setting on the inverter?

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Hi I am having the same issue as what's described here, i have noticed that it's only intermittent when the inverter is on, if i switch it off then all the numbers are rock solid, Volts, amps and watts are all consistent if it's switched off. i have disconnected everything except the batteries and the panels. it makes no difference whether i have the AC out connected or not. this makes me think that the wiring can't be the issue as there are no wires connected except for the batteries and the panels. i have 4 panels (360W*4) connected in series and 4 (Deep Cycle Lead Acid) batteries also connected in series. Please any advice would be greatly appreciated. I have the KODAK OGX 5.48 Solar Off Grid Inverter. So the issue only happens if the inverter is switched on, if off then it charges really well ??? PS : Nothing is connected to the AC out when testing.

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On 2020/08/10 at 8:55 PM, adrian123 said:

i have 4 panels (360W*4) connected in series

That's way too much voltage. The maximum rated voltage for MPPT tracking is 115 VDC. I'm guessing that 360 W panels have a Vmp of around 38 V, so 38 x 4 = 152 V.

You should rewire as 2S2P (two pairs of panels in series, each string of 2 paralleled).

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On 2020/08/11 at 1:51 PM, Coulomb said:

That's way too much voltage. The maximum rated voltage for MPPT tracking is 115 VDC. I'm guessing that 360 W panels have a Vmp of around 38 V, so 38 x 4 = 152 V.

You should rewire as 2S2P (two pairs of panels in series, each string of 2 paralleled).

That inverter has a 450V MPPT https://solarequipment.co.za/product/kodak-solar-off-grid-x-inverter-mksii-5kw-48v/

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16 minutes ago, gooseberry said:

That inverter has a 450V MPPT

Oops, sorry. In that case, is 4S enough in poor light conditions? My rule of thumb is 6S minimum for the 450 V max models, and 3S max (if 60 cells) for the 145 V max models. So when I see 4S, it seems something must be wrong. Perhaps the 360 W panels have more than 72 cells.

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