[Tomnavigator]

Hello,
I am going to install a photovoltaic solar array near my swimming pool. My house is surrounded by trees and the only open area for solar panel installation is by my swimming pool. I have poured a 60 foot by 25 foot concrete pad at the south end of my pool and will install the solar panels above this pad. The solar array will be a grid tie system that converts the solar power to AC at the array and feeds power a local panel box then to my main panel at my house. The wire I am asking about is the wire from the local panel at the solar array to the main panel at my house. The distance from the electric panel at my solar array to my service panel in my house is approximately 270 to 300 feet. Use 300 feet for the wire length. I will be installing 17,360 watts of solar panels that will tie to my household 240V AC power. This calculates to 72.3 amps (at 240 V) continuous power generated. The wire length of 300 feet includes extra length to go underground, into my attic, avoid tree roots, avoid septic lines, etc. The issue is voltage drop because of the long run of wire. The DC to AC inverter matches up its voltage to the house voltage and voltage drop is important.
I am considering 1/0 copper wire.
1) I would like to know what size wire is recommended for my situation;
2) What wire would be recommended for 90 amps under these conditions;
3) If I install a larger wire, How many amps can the next larger wire size carry under these conditions.
I am asking the second and third question because I may expand the solar array in the future and would like to know how many more amps in solar panels I can install without changing out wire. I estimate the wire cost between $3,000 - $5,000 and do not want to have to replace it in the future.
The information is summarized below.

300 foot wire run length
72.3 amps continuous load at 240 volt AC
All wire will be run in conduit 120 ft underground, 100 ft above ground, 50 ft in attic.
1) Type and Size of wire recommended for 72.3 amps 300 ft in conduit
2) Type and size of wire for 90 amps, 300 ft in conduit
3) Additional amp carrying capacity (considering voltage drop) for next larger wire size.
Thanks for your assistance with this.

[tkrussell]

The results of using an on line voltage drop calculator found at:

Voltage Drop Calculator


1 conductors per phase utilizing a #1 Copper conductor will limit the voltage drop to 2.69% or less when supplying 72.3 amps for 300 feet on a 240 volt system.
For Engineering Information Only:
110.0 Amps Rated ampacity of selected conductor
0.1427 Ohms Resistance (Ohms per 1000 feet)
0.046 Ohms Reactance (Ohms per 1000 feet)
7.199999999999999 volts maximum allowable voltage drop at 3%
6.441. Actual voltage drop loss at 2.69% for the circuit
0.9 Power Factor


What I don't know is how many conductors are needed so I can size the conduit.

I suspect 2 inch PVC Sch 40 would suffice.

[hfcarson]

Just for fun... how close is the closest edge of the swimming pool and any part or piece of the solar array? Is the solar array inside the fencing for the pool?
(I'm sure you considered this but please... humor me!)

[Tomnavigator]

Thanks for your help.

tkrussel,
My installation will be single phase 240 volt. I will be running four conductors out to the solar array so I can have a neutral wire for 120 circuits and a dedicated ground wire. I was planning on 2 inch pvc conduit.


hfcarson,
The swimming pool is an inground 20 X 45.5 foot rectangular pool oriented north to south. The closest part of the solar array will be 15 feet south of the pool and 12 feet above the pool. I am building an eight foot tall block wall around the existing deck around the pool. The block wall will be 38 feet wide (east west) by 94 feet long (north south). The solar array will cover the southern most 20 feet of the wall and will shade the deck area on the south end of the pool. I will be installing 70 solar panels total. The area inside the block wall will have 44 of the panels and the remainder will be installed continuing west from the 44 panels.

[tkrussell]

2 inch Sch 40 PVC can handle up to 8- #1 THHN/THWN or 9- #1 XHHW.

Assuming four of either will be used, they will fit very nicely, and looks like enough room for a 300 foot pull.

Be sure to use wire lube to help reduce the friction during the wire pull.

Any 90 degree sweeps (elbows) should be steel, to prevent the wire from burning through plastic PVC sweeps during the pull.