Are multiple SPDs really required when panel to MPPT wiring is longer than 33ft/10m?

[Rob_in]

Planning a solar install here:

- Rooftop panels in 3 strings of 3 series to a single MPPT charger.
- Charger, inverter, etc. will be in a cabinet approx 80ft/25m from the panels.
- The 80ft/25m wiring route from panels to charger is into & through the house, 16ft/5m or so underground to the garage then 10ft/3m or so inside the garage to the MPPT charger.

There are 2 options for combiner box, etc:

1. I read in various manufacturer instructions that say there should be an SPD near the panels and another near the MPPT charger if there is more than 33ft/10m between these. So on this recommendation the combiner box should be placed directly inside the house with breakers & SPD, with a single, large gauge cable to the MPPT charger and have a second SPD there.

2. However... we already have a large electrical box around 23ft/7m inside the house on the route the wiring would follow. This would be an ideal location to run each string to and have a combiner box with breakers and a single SPD. This option would be far more convenient for installation and access to the combiner breakers & SPD.

I am thinking that while option 2 goes against SPD recommendations surely with such a relatively short wiring run either side of a single SPD it would still offer the necessary protection.

Any thoughts/recommendations on this?

 

[timselectric]

The purpose of the SPD is to shunt (catch) the surge that could get induced on the wiring before it gets to your equipment. Near the SCC (always recommend) , protects your SCC. Near the solar panels (optional), protects the solar panels.

 

[Rob_in]

The purpose of the SPD is to shunt (catch) the surge that could get induced on the wiring before it gets to your equipment. Near the SCC (always recommend) , protects your SCC. Near the solar panels (optional), protects the solar panels.

Thanks - that makes sense.
In that case, I think the most convenient installation option would be to put the combiner stuff (fuses/breakers) in our existing electrical box part way along the wiring route and put one SPD right next to the SCC.

 

[再生可能 エネルギー]

The purpose of the SPD is to shunt (catch) the surge that could get induced on the wiring before it gets to your equipment.
Near the SCC (always recommend) , protects your SCC. Near the solar panels (optional), protects the solar panels.

I have PV Junction Boxes on my roof with a PV Switch and SPD for each string.
The SPDs are connected on the PV side of the PV switch.

Question:
I have another PV switch before the SCC, and I wonder if I should put:
- (1) the SPD before the PV switch or
- (2) between the output of the PV switch and the SCC?

Is the (2) implementation correct? (I did this way because this way was more practical)

 

[timselectric]

Question:
I have another PV switch before the SCC, and I wonder if I should put:
- (1) the SPD before the PV switch or
- (2) between the output of the PV switch and the SCC?

Either is fine. It will protect your equipment whichever way you prefer.