I want to install an ESS system with the Multi RS Solar and wonder about the requirements regarding surge protection. The manual of the Multi RS shows that the PV port has “Overvoltage Category OVCII”. Does this mean that the product is internally surge-protected ? The Victron installation schemes all show circuit breakers on the PV input but none shows a surge protection device. I guess it always makes sense to install an SPD but is it really necessary ?
We used to include SPD’s in our exterior disconnect boxes. They have IMO disconnect switches, Mersen touch-safe midget fuse holders, and Mersen or other brands of SPDs depending on what was available at the time. It’s sometimes difficult to get them, especially the Mersen DIN-rail mounted ones, so earlier this year I asked other professional installers we sometimes work with who generally deploy Enphase, Solar Edge, or other brands if they used SPDs in their installations and they all said no. Most of their installations are going to be roof-mounted vs ground mounted. Most of our installations are ground mounted.
I’m in Ohio, USA and our regulations are likely to be different from where you live. So make sure to check the local regulations.
Using SPDs on the PV strings certainly can’t hurt. They would likely not prevent a direct lightning strike from entering the home but could possibly be useful to drain static charge or surges from lightning strikes farther away.
I honestly don’t know the consensus opinion.
Getting the lower voltage SPD’s for the voltages used in small systems can be difficult, as the main bulk of DC SPD’s are 600V, 1000V and now 1500V.
Getting 75V- 250V DC SPD’s is more of a problem, and the smaller arrays are less susceptible anyway.
Good installation practice like avoiding large loops in PV cabling and grounding the mounting frame are usually sufficient. If you are planing a large array in an exposed position prone to lightning strikes, then precautions would be needed.
Great point. UL3741 (US standard) doesn’t require SPDs now that I think of it. Sufficient grounding of the array racking/frame along with co-listed equipment doesn’t specify SPDs I think.
Thanks for the replies so far. I guess everything depends on local regulations. I’ve checked France and Belgium : both require SPD’s to be installed between the PV panels and the inverter. But it seems to be much ado about nothing, given the consensus that SPD’s can’t hurt but don’t add much to the safety of domestic installations (5 tot max 10 kWp).
There was recently a topic regarding SPDs for the Victron MPPTs. There are some links and information, that may be useful for you.
Yes, avoiding large induction loops is an important factor! If the cable length are 10m or above, you can think about surge protection measures.
Installing the cables inside of the PV frame (c like shape) could also avoid induction. Also ground the frame on the edges or integrate it in a building protection system as required.
For SPD you can ask specialized manufacturers (1 example is Blitzschutz, Überspannungsschutz, Arbeitsschutz I DEHN )
Ask local companies which are bulding lightning protection systems for the regulations.