Running DC PV Cables 60 Feet in Conduit Under Eve of Back of House vs In HOT ATTICK???

RevMikeB

New Member
Joined
Feb 27, 2022
Messages
94
Resistance Difference with DC PV Cables 65 Feet in Conduit Under Eve of Back of House vs In HOT ATTIC??? I'm NOT asking which is easier to install. I'm interested in knowing if the HEAT in an attic with DC cables in conduit will have more energy loss and it would be better to run it under the eve outside? I will be using 8 AWG and will have a total of 6 wires running in the conduit to the inverter, so I was planning on using 1 inch conduit. Two strings will each run 4,690W / 523 max volts and the third will run 4355W 485 max volts for a total of 13,735W. The fourth string will connect close to the inverter and will carry 5,360W and 596 max volts from the extended garage for a grand total of 19,095W. The current for each string is 8.97A. Also, if I'm only running one DC string from the garage to the inverter (two wires) in conduit, does it have to be the same size as the 1 inch conduit that it will later connect to right at the inverter or is it required to be smaller?
 
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rickst29

Solar Addict
Joined
Mar 27, 2021
Messages
644
Location
Reno, NV
In the attic, which is not inhabited space, you can simply mark and bundle the Solar DC wires with anchors on each strut or rafter post. No conduit at all, until you make the vertical runs down to the Inverter(s). That saves a ton of money, in comparison to expensive liquidtite conduit. The conduit packs the wires fairly tight and has insulation value, it also has sunlight exposure and warms up. (Besides, a pair of those will be kinda ugly). Although the hot attic may reach nearly 60 degrees C on warm days, the slight power loss is insignificant in comparison to the conduit cost.

The garage string can use smaller conduit, with only an adapter at the inverter.
 
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