totalconfusion
New Member
- Joined
- Dec 24, 2020
- Messages
- 62
Hello wonderful people,
I’m making a PV combiner box and wanted to run some questions past you guys before I commit purchasing anything.
The combiner box will be used with a 2S4P PV set up.
From what I have gathered, a combiner box should consist of:
# Individual fuses for each STRING of panels
# SPD (Surge protection devices) also called TVSS (Transient Voltage Surge Suppressor)
# A switch
Are the following statements correct?
1. The individual fuses should be rated at 1.25x total short circuit current of each string – in this case, 26.95A
2. We only need one fuse per string as only the positive is being fused
3. The SPD will do nothing if it isn’t hooked up to an earth (grounding rod)
Questions:
1. Can the 2x individual fuses and the 2P switch be replaced with a single 4P circuit breaker? If so, are circuit breaker current ratings for each INDIVIDUAL input or is it a CUMULATIVE total
2. For the isolation switch, do we need to switch both positive and negative poles? Would we need a 2P unit or 4P
3. I can’t find the Maximum Series Fuse Rating on the panel spec sheet. Can we calculate it some other way?
Thanks a bunch people
I’m making a PV combiner box and wanted to run some questions past you guys before I commit purchasing anything.
The combiner box will be used with a 2S4P PV set up.
Total number of PV panels | 8.00 |
Total Open circuit voltage (Voc) | 99.88V |
Total Short circuit current (Isc) | 21.56A |
From what I have gathered, a combiner box should consist of:
# Individual fuses for each STRING of panels
# SPD (Surge protection devices) also called TVSS (Transient Voltage Surge Suppressor)
# A switch
Are the following statements correct?
1. The individual fuses should be rated at 1.25x total short circuit current of each string – in this case, 26.95A
2. We only need one fuse per string as only the positive is being fused
3. The SPD will do nothing if it isn’t hooked up to an earth (grounding rod)
Questions:
1. Can the 2x individual fuses and the 2P switch be replaced with a single 4P circuit breaker? If so, are circuit breaker current ratings for each INDIVIDUAL input or is it a CUMULATIVE total
2. For the isolation switch, do we need to switch both positive and negative poles? Would we need a 2P unit or 4P
3. I can’t find the Maximum Series Fuse Rating on the panel spec sheet. Can we calculate it some other way?
Thanks a bunch people