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Jay-Dee

Requirements and Recommendation for a good and safe system

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Hello all and sorry in advance if this has already been asked but I can find it with searching (perhaps searching for the wrong thing)

 

I am doing a complete revamp on my system which was installed prior to current regulations with regards to cut off switches, change overs etc... I am looking at not only being compliant but wanting to do it right!

My new setup will be as follows

  • 1x Axpert King 5K inverter
  • 3 banks of panels (2 in series, 2 parallel per set), totalling 12 panels
  • 1x Narada 40V 100AH Li-ion battery

Setup will be fed from the grid only when PV and battery are depleted / below 20% DOD. 

"Safety" in my system currently is as follows (all mounted in the garage with the inverter and battery)

  • My inbound current goes through a dual pole circuit breaker and out via a digital AMP & Volt meter to the inverter (shows me the draw and confirms if there is live current)
  • My return current goes through a dual pole circuit breaker and out via a digital AMP & Volt meter to the inverter (shows me the draw and confirms if there is live current)
  • Solar Bank (currently only 1) goes through a DC circuit breaker to the inverter

Things that I am going to add to the above this week while upgrading

  • Battery disconnect / DC circuit break between the inverter and battery (even though the battery has it's own breaker). This will also have a digital volt meter to confirm if there is live current
  • DC circuit break per solar bank and then another combining all three banks prior to the inverter. This will also have a digital volt meter to confirm if there is live current

 

My questions are... In addition to the above, do I need any of the following and can you confirm if it is for regulation or doing it right (interest sake and for others to know)

  • Manual change over switch. The inverter has this built in and I have no intention of running the without the inverter even if it fails, I would rather fix the problem than bypass
  • Fuses on solar and / or battery
  • Anything else / changed on the above

 

Thanks in advance

 

 

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Hi Jay

You seem to be OK, I also do not have a mechanical bypass, with all the in and out going breakers one can safely disconnect the inverter - but we will have to do some wiring in case of a permanent issue..

You should consider adding surge protection on the PV (on or close to the Inverter).

There is discussions in this forum on PV DC fuses - but each string should ideally have a fuse just above the max current source. So if 1 string has 2 in serie that source is app. 2 x 9amp so a 20Amp fuse is OK.

(My Axpert can handle 450 V DC, so I have 8 panels in serie - the source stays 9 amp, so a 12 amp fuse in that string is ok.)

On my second Inverter I have 12 panels: 6 in serie, 2 parallel strings - the source becomes 18amp so a larger fuse (20amp) is needed if combined.

Why not consider more Series connections? it lowers the current.

The battery should have a DC fuse even with breakers, you can check the battery specs but 125amp should do it..

Keep well!

Jaco 

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