SPD Questions

Started by Eelectric, May 29, 2023, 07:40:06 AM

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I have off-grid cabin. My set up is a little different. I'm using ideal diode "charge controllers" to charge a 14.4kWh lithium battery. I have 5 parallel strings of two panels.

I would prefer the SPDs to be outside mounted on a box. All 5 positive strings need to remain isolated. All five negatives connect directly to the battery and don't go through the charge controller.

If the negatives are combined. Would I be able to use 3 Midnite SPDs to protect this system. All the negatives would be combined on a bus bar. The first SPD would be connected to the negative bus bar and one of the positive strings. Could other two SPDs connected to two positive wires or does the black wire have to be connected to negative for the work surge protection to work. Of course the green wires would be connected to a ground bus bar.

I've noticed the positive SPD lead is usually connected to a positive combining bus bar in a combining box. Because the strings stay separate, i assume it would be okay to have the fuses/breakers just before the charge controller. For easy access and to disconnect panels if ever necessary. Thanks in advance for your advice.