commercial combiner boxes all seem to do Circuit B. The reason for this is that if there are multiple strings, you would need a separate SPD per string. With a single string as shown above, the only difference I can see is that if the SPD is before the fuse, it will no longer protect your charge controller once the fuse is blown. (but if the fuse is blown, the need for protection of the controller is drastically reduced).Which of these two wiring diagram is the correct method of installing a DC SPD for Solar Panels?
Please give your reason.
View attachment 97323
Assume that the above listed components are inside a single box.
Thanks
Dan
I came to the same conclusion that the SPD should be between the fuse and charge controller, but not to protect the strings. Instead, it is to protect the charge controller. (Once the fuse blows, the string will no longer be connected to the SPD.B
When using string protectors such as fuses, DC breakers or string diodes together with SPDs, the SPD must be installed between the
fuses and the inverter, otherwise the PV strings would be unprotected if the fuse is triggered.
They do like selling their overpriced SPDs!!
This brings up the question of the location of the SPD.
And redundancy , for double profits. lolThey do like selling their overpriced SPDs!!
Midnight is saying to put one in the junction box and another near the inverter. If you trace it out, they are in parallel and on the same circuit.This brings up the question of the location of the SPD.
Near the panels or the inverter.
In both cases, I chose the same as this diagram. Connected directly to the long wiring.
Mine is close to the SCC, with the breaker between the two. In my opinion the "source" for the SPD is the possible surge. Which in a nearby lighting strike, would be the long wires. I believe that either end would probably protect equally. But, I have Mine at the end closer to the ground rod.Midnight is saying to put one in the junction box and another near the inverter. If you trace it out, they are in parallel and on the same circuit.
Overkill? I think so but that is just my oppinion.
If you are using just one there are arguments both ways. It is always better to dump the surge closer to the source.... so that argues to put it closer to the panels. However, the ground wire up to the combiner box is going to offer a fair amount of impedance to the path and reduce the effectiveness of the SPD.
Exactly what I was banking on putting the SPD between the panels and SCC/Inverter: The MCB/Fuse will become an open circuit no more surge to pass to SCC/inverter.(but if the fuse is blown, the need for protection of the controller is drastically reduced).
But they've got those pretty blue LED's on them!They do like selling their overpriced SPDs!!
Notice that they put the SPD after the fuse.
There's the data! I sure can't argue with that.
285.24 Type 2 SPDs. Type 2 SPDs shall be installed in accordance with 285.24(A) through (C).
(A) Service-Supplied Building or Structure. Type 2 SPDs shall be connected anywhere on the load side of a service disconnect overcurrent device required in 230.91, unless installed in accordance with 230.82(8).
(B) Feeder-Supplied Building or Structure. Type 2 SPDs shall be connected at the building or structure anywhere on the load side of the first overcurrent device at the building or structure.
(C) Separately Derived System. The SPD shall be connected on the load side of the first overcurrent device in a separately derived system.
What software did you use to create this wiring diagram?Which of these two wiring diagram is the correct method of installing a DC SPD for Solar Panels?
Please give your reason.
View attachment 97323
Assume that the above listed components are inside a single box.
Thanks
Dan