2P or 1P SPD

This is probably a really simple question, but I figure I’d rather ask than make an unnecessary booboo. Regarding surge protection, is there any practical difference between using 2 x 1P devices and a single 2P device?

I stand corrected, but for surge protection it does not really matter if you have a 2P or 2x 1P. (For things that give power like a battery you want to break both the same time)

The important thing is that for surge protection is that you need all the wires protected. So only one side of the cable with 1P is not good enough. Both sides with 2P or 2x 1P is fine.

That’s what makes sense to me too, but I just wanted to double check. I’m planning on using 2 x 1P 275V SPD on the AC side and just want to check that this isn’t a dumb idea. DC side will get 1 x 2P 600V SPD per string. Ideally I’d prefer a lower Uc rating as the Sunsynk/Deye MPPT is rated for 500V but these don’t seem to exist.

You can do this, nothing wrong with it. The light on the one connected to the neutral wire will not light up as there is no potential difference between neutral and earth (Bonded). In most cases only the one connected to will offer protection once the potential difference between live and earth exceeds 275 volt. The neutral one in my opinion offers no real protection, but we do install them as its required.


I notice this SPD has an AC and DC rating. My panels will be at about 200V, so could I use this SPD on the DC side too, or do I need a specific DC SPD for that?

900600.pdf (123.6 KB)

Yes, you need one designed for DC. They are fairly expensive and are normally rated for 600vdc to 1500volt dc. Will post a few examples later.

Thanks. I’ve been looking at a couple of DC options (and actually found some 450V items earlier today) was just wondering as those have the DC rating on the spec sheet too.

I am using one of the Citel range of SPDs. But as Jaco said, these are quite expensive!

See Citel Surge Protection DC/PV Type 2 220VDC (DS240-220DC) | Sonop Solar

Anyone used these before. I just did a quick search and these look to have a good price with 530Vdc.

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Should have just read this thread before asking why the neutral wire’s light is not switched on while you were here today…

Not A Problem.