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diy solar

Solar panels drawing current

Redbeardbeer

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Joined
Nov 7, 2021
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Hi all.

I'm in the process of adding a battery to my solar system.
Currently have:

2x200 watt panels wired in parallel with a pair of Y cables. Panels are a 'no name' panel from a local supplier (I'm in New Zealand) so I assume they're chinese. The spec sheet doesn't give much away apart from the usual Pmax, Vmp, Lmp and Voc etc.
1x 1000w Sun Grid Tie inverter

Battery I'm putting in is a custom built 14S32P battery using 18560 cells.

As soon as I enable "discharge" on my JK BMS, the 10A breaker from the battery trips (yes it's only 10A as it's all I have and I'd rather a small one trip if there are any initial issues, as evident from my current (pun intended) problem).

I opened the little box up under the panels when I got them as I was curious to see what was in there, and there were 3 (maybe 4, I forget) diodes. Is this the 'blocking diodes' that the internet talks about to stop the issue that I'm having?

If these are 'blown' (annoying if so as they are basically brand new panels), would this cause these issues? Or is there something else I'm missing?

Cheers!
 
As soon as I enable "discharge" on my JK BMS, the 10A breaker from the battery trips (yes it's only 10A as it's all I have and I'd rather a small one trip if there are any initial issues, as evident from my current (pun intended) problem).

If the inverter was wired into the system at the time, then that could be the problem. The capacitors in the inverter draw a large initial current to charge. Disconnect the inverter and try again.
 
10A - too small for inverter to battery.
Is that a 12V system? 120W, far too low for 1000W watt inverter.
Sure, might be safe if you have a fault. But only if it can interrupt the thousands of amps your lithium battery might be able to source.

Is the inverter also the solar charge controller?
You could precharge capacitors through resistor or light bulb before closing breaker.

Once you confirm no shorts, put in a large enough breaker/fuse.

You can check PV panel Voc and Isc (if you have suitable ammeter) stand-alone disconnected from system. If any diodes shorted, that will show up in voltage.
 
Ok so I have put a solar charge controller POWMR in the middle so now the setup is as per the pic below and it appears to be working and not doing the weird current draw as before.
The only question I have is, when I put a clamp meter on the main live feed in the power box of the house, the house at the moment is currently drawing around 2.6A (240v so around 620 watt).
When I fire up the inverter and draw from the battery and solar and set the inverter limiter to 500watt - the clamp meter still reads around 2.7A.
I have the inverter plugged into a little smart plug thing that shows power passing through it - and it's showing there is 500-530watt passing through it. So the inverter is pumping out power - but where is it going if the main feed into the house is still showing the same as if I haven't got the inverter on at all? *confused*

Merry Xmas btw
 

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10A - too small for inverter to battery.
Is that a 12V system? 120W, far too low for 1000W watt inverter.
Sure, might be safe if you have a fault. But only if it can interrupt the thousands of amps your lithium battery might be able to source.

Is the inverter also the solar charge controller?
You could precharge capacitors through resistor or light bulb before closing breaker.

Once you confirm no shorts, put in a large enough breaker/fuse.

You can check PV panel Voc and Isc (if you have suitable ammeter) stand-alone disconnected from system. If any diodes shorted, that will show up in voltage.
Oh and yeah the inverter has an MPPT solar controller built into it - I just don't think it was happy about having a battery in the mix. Dunno. Seems better now with a proper external solar charge controller.
 
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