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greenarc avatar image
greenarc asked

The question I never got around to asking but now remember

So I just want to know for sure how to obtain an accurate reading of the batteries from the MPPT controller in setup stage. I always go with a certain order,- first the battery to controller, then load, then inverter, then Pv. Due to my configuration however, it is a little annoying to have to dismantle the batteries or inverter, and have to reconnect in order again, and go through the whole ‘spark’ of connecting the inverter again. So it would be nice to just keep it all connected. Not sure if you know what I mean, but question is; does it really matter about the order, given that there is an he mix? -for example, if I add the inverter to batteries BEFORE I connect the MPPT, will it REALLY affect the reading of voltage from the MPPT controller?


oh please note that I have a bluetooth temperate sensor. So if that changes anything, given that it is reading from a-close to the terminals. Was told this improves accuracy of reading (makes sense) however, nothing I read explain you must put this on in a certain order…


just like to be clear on things :)

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2 Answers
basil katakuzinos avatar image
basil katakuzinos answered ·

Put simple the best reading will be the one closest to the batteries, as their will be some voltage loss across conductors. If your MPPT and Inverter are connected together (Perhaps with a GX device) then the MPPT will use the inverter voltage (which can be obtained through a voltage sense cable, from the BMS of from the inverter itself)

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greenarc avatar image greenarc commented ·
Thanks!
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shaneyake avatar image
shaneyake answered ·

If you are using a Smart Battery Sense, then it will send voltage readings to the MPPT.
The order does not matter. The reason you normally connect the MPPT and Inverter first is to pre-charge the huge capacitors in the inverter to prevent a spark when connecting the battery.

If you install a pre-charge switch/circuit then you can connect and disconnect the inverter easily.
But you also don't need to disconnect you inverter. Just turn it off at the switch on the inverter.

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greenarc avatar image greenarc commented ·

I figured the precharge of the inverter would affect voltage. The inverter gets directly connected to the batteries, and I normally just add it after the MPPT.

So to be clear then, no order matters if I have the voltage sense? I can live with that, but a good idea to get a pre-charge switch.

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shaneyake avatar image shaneyake greenarc commented ·
The order does not matter, the voltage drop from your batteries to MPPT does but if you have a Battery Sense if should help with that.


I would always recommend going from the batteries to a BUS bar then connecting MPPT and Inverter to that BUS bar with approte fuses.
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