First, thanks in advance for the time and energy you all put into this to help the rest of us. It is so appreciated.
I am slowly trying to build almost exactly the OFF GRID 48v system blueprint on this site in a solar shed with 2 EG4 6500EX-48 inverters and 16 ground mounted Blue Sun 460W/575W Bifacial panels. (Pics and specs attached). The shed will have the sole purpose of providing 240v EV charging. I finally have the panels installed and I buried 4 sets of 10 AWG Copper PV wire in 2 inch PVC conduit from the array to the shed. I had planned to connect 4 panels in series and then run the 4 sets of wire to the 4 PV inputs on the 2 inverters. (PV1/PV2 PV1/PV2). The array is approximately 35 feet away from the shed but the cable run is in a 'L' shape and the distance will be approximately 50-60 feet to the first set of panels. (and approximately another 12 feet to each of 3 subsequent connections). The longest wire run should be approximately 90 feet.
Question #1 - Can someone please verify: I'm derating to 70% for 8 conductors in a conduit and using an operating current of 10.86 * 1.56 = 16.94..... I am still well within range for using 10AWG Copper PV wire. Am I understanding this correctly?
Now I am going down the grounding rabbit hole and I see several different ways to navigate the conflicting opinions I think I see. (Note this will be an off grid system and while I will probably have electrician take a look before I turn it on, I will not be having a building inspector look at it. I am concerned about safety and functionality, not code.)
It seems like the preferred method (Mike Holt etc.) is to not ground the array locally but to ground it back at the shed on one common ground connected to the shed panel. The problem is I already buried the conduit and I don't think I can pull another cable through it...maybe . I believe I have 4 options on how to handle this:
1- ground the array locally to its own grounding rod and be done with it.
2- ground the array locally to its own grounding rod and connect the grounding rod at the array with the grounding rod at the shed. I can bury a 6 AWG bare copper wire in a direct line to accomplish this.
3- ground the array to a 6 AWG bare copper wire and just bury that and connect it to the grounding rod at the shed.
4-Ground the array to one (or two) of the existing already buried 10 AWG copper PV wire changing it to a grounding wire and use the remaining 6 wires to connect the panels to the inverters in a 5/5/6 configuration instead of 4/4/4/4. The first inverter would have 5 panels on each of the 2 PV inputs. The second inverter would have 6 panels on just 1 PV input.
#4 seems like my preferential solution as it requires no more digging or purchase of additional wire but I wanted to hear the comments about it.
Question #2 - Which of the 4 options seems like the best solution and why? Are there any other concerns I am missing?
The house is about 20 feet from the shed and has an emergency generator hookup plug for about 10 circuits. Down the road and in case of a long power outage I would like to connect the shed to the generator input at the house with a 240v extension cord. I understand that I would have to reconfigure the EG4s to not have a neutral/ground bond before I connect the shed to the house. Once connected the whole system will not have 1 common ground but 2 approximately 35-40 feet apart. I feel this is ok as it would be only a temporary connection and I could disconnect it if I was concerned about a ground loop during a bad thunderstorm.
Question #3 - Do you see any issues with my temporary connection from the shed to the house based on the information supplied?
These are the brackets I am using:
https://www.amazon.com/gp/product/B0B82LYG93/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
I understand about galvanic corrosion and using special stainless steel lugs to connect the copper wire with the aluminum rack when bonding the panels/rack together for a ground. I did not use WEEB conectors between the solar panel frame and the rack.
Question #4. Do I need to go back and install the WEEB connectors? And if I do can I get away with 1 or 2 per panel instead of 4 for the 4 connection points?
Thanks again for all your insights.
I am slowly trying to build almost exactly the OFF GRID 48v system blueprint on this site in a solar shed with 2 EG4 6500EX-48 inverters and 16 ground mounted Blue Sun 460W/575W Bifacial panels. (Pics and specs attached). The shed will have the sole purpose of providing 240v EV charging. I finally have the panels installed and I buried 4 sets of 10 AWG Copper PV wire in 2 inch PVC conduit from the array to the shed. I had planned to connect 4 panels in series and then run the 4 sets of wire to the 4 PV inputs on the 2 inverters. (PV1/PV2 PV1/PV2). The array is approximately 35 feet away from the shed but the cable run is in a 'L' shape and the distance will be approximately 50-60 feet to the first set of panels. (and approximately another 12 feet to each of 3 subsequent connections). The longest wire run should be approximately 90 feet.
Question #1 - Can someone please verify: I'm derating to 70% for 8 conductors in a conduit and using an operating current of 10.86 * 1.56 = 16.94..... I am still well within range for using 10AWG Copper PV wire. Am I understanding this correctly?
Now I am going down the grounding rabbit hole and I see several different ways to navigate the conflicting opinions I think I see. (Note this will be an off grid system and while I will probably have electrician take a look before I turn it on, I will not be having a building inspector look at it. I am concerned about safety and functionality, not code.)
It seems like the preferred method (Mike Holt etc.) is to not ground the array locally but to ground it back at the shed on one common ground connected to the shed panel. The problem is I already buried the conduit and I don't think I can pull another cable through it...maybe . I believe I have 4 options on how to handle this:
1- ground the array locally to its own grounding rod and be done with it.
2- ground the array locally to its own grounding rod and connect the grounding rod at the array with the grounding rod at the shed. I can bury a 6 AWG bare copper wire in a direct line to accomplish this.
3- ground the array to a 6 AWG bare copper wire and just bury that and connect it to the grounding rod at the shed.
4-Ground the array to one (or two) of the existing already buried 10 AWG copper PV wire changing it to a grounding wire and use the remaining 6 wires to connect the panels to the inverters in a 5/5/6 configuration instead of 4/4/4/4. The first inverter would have 5 panels on each of the 2 PV inputs. The second inverter would have 6 panels on just 1 PV input.
#4 seems like my preferential solution as it requires no more digging or purchase of additional wire but I wanted to hear the comments about it.
Question #2 - Which of the 4 options seems like the best solution and why? Are there any other concerns I am missing?
The house is about 20 feet from the shed and has an emergency generator hookup plug for about 10 circuits. Down the road and in case of a long power outage I would like to connect the shed to the generator input at the house with a 240v extension cord. I understand that I would have to reconfigure the EG4s to not have a neutral/ground bond before I connect the shed to the house. Once connected the whole system will not have 1 common ground but 2 approximately 35-40 feet apart. I feel this is ok as it would be only a temporary connection and I could disconnect it if I was concerned about a ground loop during a bad thunderstorm.
Question #3 - Do you see any issues with my temporary connection from the shed to the house based on the information supplied?
These are the brackets I am using:
https://www.amazon.com/gp/product/B0B82LYG93/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
I understand about galvanic corrosion and using special stainless steel lugs to connect the copper wire with the aluminum rack when bonding the panels/rack together for a ground. I did not use WEEB conectors between the solar panel frame and the rack.
Question #4. Do I need to go back and install the WEEB connectors? And if I do can I get away with 1 or 2 per panel instead of 4 for the 4 connection points?
Thanks again for all your insights.
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