where to use 150,300 and 600V SPD's?

[Westbranch]

I was thinking about SPD's for my system work in the spring, looked at one supplier and all they had (now) was 600V SPDs, and I realized I have not seen info on where you would use all 3 sizes.

Ryan can you give us some guidelines as t where you recommend them?
thanks.

[Halfcrazy]

Well basically there model is there MAX working DC voltage. So if it is on the DC input (PV) of say a Classic than I would use an SPD300. If it is going on a 120 or 120/240 VAC scenario than use the SPD300. If it is the PV side of the Grid tie Inverter than use the SPD 600. The SPD 115 is mostly for low voltage control stuff or onto the actual battery etc. Just keep it below 115vdc

Ryan

[Westbranch]

Thanks Ryan.

Hmmm,  for a 4 panel (12V nom.) array I was going to use a 115 SPD Mpp ~70V  and Min temp  Voc would be in the 90V range.
If I up the array to 5 panels,  working (Mpp) V would be ~ 85V and Min temp Voc would be ~115V+,
Should I reconsider using the 115?

[Halfcrazy]

Yes my rule of thump on a PV side SPD is to size it around the charge controller. It will be way to easy to forget there is a limit on the system do to an SPD115 and say 2 years from now add a PV in series and have the SPD bleeding to ground