Roswell Bob
Solar Enthusiast
Here in New Hampshire (The Granite state) we have a lot of ledge to deal with so running wires underground may be difficult/impossible. To complicate matters I have a large stone wall between point A and point B. I am thinking a combination of underground and overhead.
I have two panel arrays *Each 4S/2P. One is the REC250PE and the other array are Canadian Solar. In any case each array is about 120v at 18A. I will be running Midnight Solar charge controllers with the Arc Fault protection.
I think it would be best to install 2 poles one by panels and another near house where the wires would enter. I believe good engineering practice would dictate that the Negative and Positive leads of each array be near each other along with an earth ground brought up to each array. By 'near each other' I mean jiffy-tie or tape together to reduce stray inductance. I will use this earth ground with MOVs or other protection device in effort to protect against lightning strikes. This DC Ground will originate at ground rod near entrance to house. There is another AC Ground with it's own rod about 20' away. I don't believe I need to connect the two grounds together. I would like to put cross at top of poles and run the 6 leads (+-,+-, and two grounds) about 4" apart. This would add an old-time cool factor, but inductance between array and charge controller will cause resonance and might not be so good.
Questions follow -
Are there any obvious errors/problems in going overhead with 120VDC Lines?
Is inductance in leads between arrays and charge controllers a real problem?
What type of wire should I be using? I am thinking #12 if wires are bundled, or #14 if seperated. If wires are seperated I will still want insulation on them tho. Would the (NEC) solar panel or direct bury type be ok? I am using SO cord now as a temporary measure, but that not so good in sunlight I hear.
Would MOV or other surge devices at arrays, each pole, and charge controller be a good plan. Should MOV rating should be based on open circuit panel voltage at coldest expected temperature.
I can sink wood or steel poles into concrete. Is one better than another?
Thanks ahead for any input. I realize this is complicated and I am not an electrician so any help would be appreciated.
I have two panel arrays *Each 4S/2P. One is the REC250PE and the other array are Canadian Solar. In any case each array is about 120v at 18A. I will be running Midnight Solar charge controllers with the Arc Fault protection.
I think it would be best to install 2 poles one by panels and another near house where the wires would enter. I believe good engineering practice would dictate that the Negative and Positive leads of each array be near each other along with an earth ground brought up to each array. By 'near each other' I mean jiffy-tie or tape together to reduce stray inductance. I will use this earth ground with MOVs or other protection device in effort to protect against lightning strikes. This DC Ground will originate at ground rod near entrance to house. There is another AC Ground with it's own rod about 20' away. I don't believe I need to connect the two grounds together. I would like to put cross at top of poles and run the 6 leads (+-,+-, and two grounds) about 4" apart. This would add an old-time cool factor, but inductance between array and charge controller will cause resonance and might not be so good.
Questions follow -
Are there any obvious errors/problems in going overhead with 120VDC Lines?
Is inductance in leads between arrays and charge controllers a real problem?
What type of wire should I be using? I am thinking #12 if wires are bundled, or #14 if seperated. If wires are seperated I will still want insulation on them tho. Would the (NEC) solar panel or direct bury type be ok? I am using SO cord now as a temporary measure, but that not so good in sunlight I hear.
Would MOV or other surge devices at arrays, each pole, and charge controller be a good plan. Should MOV rating should be based on open circuit panel voltage at coldest expected temperature.
I can sink wood or steel poles into concrete. Is one better than another?
Thanks ahead for any input. I realize this is complicated and I am not an electrician so any help would be appreciated.
