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PV issue


Namreh
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Hi,

I am having issues with my PV falling away after a large load was connected for a few minutes. The PV tries to come back every few seconds( you can also hear a relay clicking when it tries to restart.

Not sure if it got something to do with the absorption charging timer(Menu 32) that was always on auto. I recently put that to 60 minutes as it was going back to float very quickly.

Settings as follows:

01: SOL

02: 80A

03: APL

04:SdS

05: USE

11: 20A

12: 50 VOLT

13: 54 VOLT

16: SNU

26: 57.6 volt

27: 55.2 volt

29: 44 VOLT

32: 60

My system is as follows:

Axpert type inverter 5kVa 4kw( see attached pic of nameplate and software version)

15 x 330w panels singed 3 in series my PV voltage show around 130 volt

The panel are positioned as follows:

3 x panels facing to get morning sun.

9 x panels facing north on angle adjustable frame

3 panels facing to get late afternoon sun

2 banks of 100a/h SonX AGM batteries

Any ideas/assistance/comments will be appreaciated.

Thanks

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3 hours ago, Namreh said:

I am having issues with my PV falling away after a large load was connected for a few minutes. The PV tries to come back every few seconds( you can also hear a relay clicking when it tries to restart.

Hi Herman (am I correct?)

At the time of the large load, are you generating enough PV to be able to power all the loads? My understanding is that some Axperts can’t blend power sources. So if you can’t power all your loads from PV it will switch to grid.

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2 hours ago, jykenmynie said:

Hi Herman (am I correct?)

At the time of the large load, are you generating enough PV to be able to power all the loads? My understanding is that some Axperts can’t blend power sources. So if you can’t power all your loads from PV it will switch to grid.

Hi,

Thanks for the reply.

Yes I do have enough PV to power all the loads. The PV drops away and tries to come back and then drop out. You can hear a relay click when this happens.

I changed the absorption setting(menu 32) from Auto to 60 minutes. Not sure if this is the cause. I found that the unit do not stay very long on the bulk charging mode, thus batteries do not get a full charge(I think)

PS, I do not drain my batteries so it might not be needed …..

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2 hours ago, jykenmynie said:

You can, but it won’t be very efficient.

It actually works very well. I get almost 1kw PV as soon as the sun rises and my PV peaks at around 11h00. With the west facing panels I then get also almost 1kw for almost 1hour extra

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5 hours ago, Namreh said:

I am having issues with my PV falling away after a large load was connected for a few minutes. The PV tries to come back every few seconds( you can also hear a relay clicking when it tries to restart.

At what time during the day does this happen, and what is the load when this happens.. The PV will typically only disconnect when it goes below the low voltage mark, or when the load exceeds the actual PV production. I would expect to see that behaviour early morning or late afternoon. 

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6 minutes ago, Jaco de Jongh said:

At what time during the day does this happen, and what is the load when this happens.. The PV will typically only disconnect when it goes below the low voltage mark, or when the load exceeds the actual PV production. I would expect to see that behaviour early morning or late afternoon. 

Hi Jaco,

Thanks for the reply.

This morning it was around 10. The load was around 2kw and the PV was around 1,2kw. I did not check the battery voltage when it happened. Normally the PV drops out and resets or something after 20 seconds. When this happened the PV kept on trying to return but dropped out every say 5 seconds and the relay click was a louder click. Will check battery voltage when this happens again.

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42 minutes ago, Namreh said:
56 minutes ago, Jaco de Jongh said:

At what time during the day does this happen, and what is the load when this happens.. The PV will typically only disconnect when it goes below the low voltage mark, or when the load exceeds the actual PV production. I would expect to see that behaviour early morning or late afternoon. 

Hi Jaco,

Thanks for the reply.

This morning it was around 10. The load was around 2kw and the PV was around 1,2kw. I did not check the battery voltage when it happened

Please give attention to the PV voltage at that moment. With all your panels I would expect a lot more than 1.2kw at 10 (depending on where you stay} Are you sure all the strings are contributing to the production. You can test 1 by one  by pulling all fuses and closing I string at a time. 

 

Where did you combine yours trings, and what is the thickness of the wire running from you point of combining to the Inverter? 

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14 hours ago, Namreh said:

15 x 330w panels singed 3 in series my PV voltage show around 130 volt

That's a lot of PV power for a 4 kW SCC, but you should get away with it because of the different orientations.

Is the 130 V loaded or unloaded?

Almost certainly, the problem is too much PV voltage. 130 V is at the upper end of full power output, and recently it was discovered that the SCCs get 30% hotter when wired 3S versus 2S. I'd say it's stopping due to a combination of excessive temperature and excessive PV voltage.

Since you have a clone with patched firmware, you can readily check temperature. One of the display screens has the maximum temperature of 4 things: the transformer, two heatsinks, and the solar charge controller. Usually, the SCC temperature will be lowest, and the transformer temperature the highest. But when the SCC disconnects, you may find the temperature reading decreasing, indicating that the SCC is the hottest part, and is likely derating the SCC output, and possibly causing it to disconnect.

Sadly, fixing this means re-wiring for 2S and 7P, which will be really awkward for your setup, and of course you'll have one spare panel.

To test this, perhaps disconnect all but two strings, and temporarily wire one of the remaining strings as 2S. In mid morning when you have the problem, compare performance of 3S versus 2S. You might find that 2S gives you more than 2/3 the power of 3S. Of course, because it's only operating on a fraction of full power, the temperature issue won't come into play, only voltage.

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9 hours ago, Jaco de Jongh said:

Please give attention to the PV voltage at that moment. With all your panels I would expect a lot more than 1.2kw at 10 (depending on where you stay} Are you sure all the strings are contributing to the production. You can test 1 by one  by pulling all fuses and closing I string at a time. 

 

Where did you combine yours trings, and what is the thickness of the wire running from you point of combining to the Inverter? 

Hi Jaco,

The main bank is on my garage roof. The run is short with 4mm cable going to combiner box on the roof. from roof it runs down to inverter with 25mm cable.

The 2 other banks is on house roof about 20 meters away. Runs to combiner box close to panels with 4mm cable, then feds to combiner box on garage roof with 12mm cable.

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1 hour ago, Coulomb said:

That's a lot of PV power for a 4 kW SCC, but you should get away with it because of the different orientations.

Is the 130 V loaded or unloaded?

Almost certainly, the problem is too much PV voltage. 130 V is at the upper end of full power output, and recently it was discovered that the SCCs get 30% hotter when wired 3S versus 2S. I'd say it's stopping due to a combination of excessive temperature and excessive PV voltage.

Since you have a clone with patched firmware, you can readily check temperature. One of the display screens has the maximum temperature of 4 things: the transformer, two heatsinks, and the solar charge controller. Usually, the SCC temperature will be lowest, and the transformer temperature the highest. But when the SCC disconnects, you may find the temperature reading decreasing, indicating that the SCC is the hottest part, and is likely derating the SCC output, and possibly causing it to disconnect.

Sadly, fixing this means re-wiring for 2S and 7P, which will be really awkward for your setup, and of course you'll have one spare panel.

To test this, perhaps disconnect all but two strings, and temporarily wire one of the remaining strings as 2S. In mid morning when you have the problem, compare performance of 3S versus 2S. You might find that 2S gives you more than 2/3 the power of 3S. Of course, because it's only operating on a fraction of full power, the temperature issue won't come into play, only voltage.

Thanks for the reply Coulomb,

Where do you see if this is a clone unit and if the software need to be upgraded perhaps.

The 130 Volt is when connected to the inverter.

Where do I see this temperature?

Appreciate the help and guidance.

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6 hours ago, Namreh said:

Where do you see if this is a clone unit

It's all on the AEVA website: Do I Own a Clone? The giveaways here are the sticker on sticker, the format of the barcode/serial number, and the cent signs instead of greek letter Φ.

Quote

and if the software need to be upgraded perhaps.

Unfortunately, these clones typically aren't upgrageable. Yours might be recent enough that they fixed that issue, though.

Quote

The 130 Volt is when connected to the inverter.

I take it that's under load then. That's too high a voltage. If it was 130 V open circuit, it might be just barely OK.

Quote

Where do I see this temperature?

On the LC Display; just use the up or escape buttons to scroll the left half of the information screen until you see a number and "°C".

Edited by Coulomb
Duh. Forgot link.
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1 hour ago, Coulomb said:

It's all on the AEVA website: Do I Own a Clone? The giveaways here are the sticker on sticker, the format of the barcode/serial number, and the cent signs instead of greek letter Φ.

Unfortunately, these clones typically aren't upgrageable. Yours might be recent enough that they fixed that issue, though.

I take it that's under load then. That's too high a voltage. If it was 130 V open circuit, it might be just barely OK.

On the LC Display; just use the up or escape buttons to scroll the left half of the information screen until you see a number and "°C".

@Coulomb Thanks for this.

I will have a look at the temperature but cannot recall that I have ever seen it higher than 55 deg.

I saw a post somewhere relating to the fans direction. Your opinion on that?

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Thx guys following this conversation with bated breath. I've also overspecced my panels and thinking about splitting them. Currently they all face north. 12x400w Canadian solar. Can I split 4 to face east and another 4 to face west. @Namrehare you happy with your split panels? I know it's one mppt but think it is doable based on my research? @Coulomb and all the other experts feel free to weigh in please. 

Oops its the same inverter I think. The RCT Axpert 5kva

Edited by Dani
Added inverter details
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2 hours ago, Dani said:

Thx guys following this conversation with bated breath. I've also overspecced my panels and thinking about splitting them. Currently they all face north. 12x400w Canadian solar. Can I split 4 to face east and another 4 to face west. @Namrehare you happy with your split panels? I know it's one mppt but think it is doable based on my research? @Coulomb and all the other experts feel free to weigh in please. 

Oops its the same inverter I think. The RCT Axpert 5kva

@Dani it is the same inverter yes, mine is just a clone.

 

My split work very well. I get at least 90 minutes extra in the morning and afternoon. Only issue (that might be to high PV related) is to wire in strings of two, mine is in strings of 3 getting around 130 volt

I have now twice had the issue where the PV falls away and only came back after I reset the system.

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