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Solar panel configuration with Axpert King 5KV in parallel(x3)


Roentgenzap
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Hi All

I recently installed 3 x Axpert King 5kva inverters in parallel (single phase). Panels are 27 x 370W Renewsys. Battery running 16 Narada AGM in 4 x 4 config. Also using Victron BMV-712. All monitored by ICC on Pi. 

 

My inverter specs for each inverter: 

Maximum PV Array Open Circuit Voltage 145 VDC

Maximum PV Array Power 4000 W

MPP Range @ Operating Voltage  60~115VDC

Maximum Solar Charge Current  80 A

Maximum AC Charge Current 60A

Maximum Charge Current  140 A

 

Panels are rated at:

Rated power (Pmax), Wp   370

Max. power voltage (Vmp), V  39.94

Max. power current (Imp), A  09.28

Open circuit voltage (Voc), V 49.12

Short circuit current (Isc), 09.80

A Module efficiency (%) 19.14

 

Currently, panels are wired in 3 series x 3 parallel per inverter. Is that the optimal configuration?

Theoretically, that is about 10kw setup (9900w to be precise). I never however see close to that during the day. The maximum I have seen recently is about 5800W coming from the PV panels (between 11am and 1pm) - and that is with sufficient load from the house (4500W) and also batteries charging. It just seems somewhat low. I understand that 370W rating per panel is theoretical and real life rating (NOCT (Wp) at 45 ± 2 0C @800 W/m2) is at 275W - even then, I should be able to get closer to 7500W from the panels. 

 

Secondly, my current inverter settings is set at 50A PV charge (per inverter) and 40A AC charge (per inverter). 

Even with available PV power, the PV battery charging never goes above about 60A in total.

 

Am I missing something here? 

Any help would be much appreciated!

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46 minutes ago, Roentgenzap said:

Open circuit voltage (Voc), V 49.12

So that's over 147 V @ 25°C. Two volts over the blow-up voltage. Worse when it's colder.

In another thread, it was discovered that Kings' SCCs derate PV power due to the extra 30°C that results from operating at very high PV voltages. Presumably MKS models would be the same.

Those panels must have more than 72 cells. Rewire for 2S. You'll end up with one odd panel, and uneven strings per inverter (no problem with that). I'm pretty sure you'll find much better solar production.

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On 2020/08/13 at 3:01 PM, Coulomb said:

So that's over 147 V @ 25°C. Two volts over the blow-up voltage. Worse when it's colder.

In another thread, it was discovered that Kings' SCCs derate PV power due to the extra 30°C that results from operating at very high PV voltages. Presumably MKS models would be the same.

Those panels must have more than 72 cells. Rewire for 2S. You'll end up with one odd panel, and uneven strings per inverter (no problem with that). I'm pretty sure you'll find much better solar production.

Thanks Coulomb

 

I can report that the rewiring was done and the PV drop-out issues I was experiencing, is gone. 

Also, battery charging on PV seems much better now. 

Thanks for the help!

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