Question

i'm looking for direction in Calculating Guy Wire Systems[wire sizing, wire angles,etc]

Answer 1

45 degrees is a good optimum angle and easy to figure out wire length and angles.

For example if you are putting up a 60 ft high pole tower for a wind plant, you would need a minimum of three guy wires placed 120 degrees apart. Placing them 120 degrees divides a circle into 3 equal segments.
If you attach a wire at the 50 ft mark on the pole and you also measure out 50 ft on the ground away from the pole you will have a 45 degree angle coming from the top of the pole and a 45 degree angle on the ground level up to the pole. Then you do this for the other two attaching wires.

Sin45 and cos45 are both equal to 0.707. This figure is multiplied by the guy wire tensile strength. Say you calculate the maximum wind force on the tower and prop is going to be 4000 lbs force.

To calculate guy wire strength for numbers above, you use a simple formula like:
Minimum Tensile strength = 4000 lbs / 0.707 = 5658 lbs of breaking strength.

For a safety factor you want to use at least twice the maximum force expected...so say 12,000 lbs of breaking strength. Look at this table for
cable thickness for 12,000 lbs and it looks like a 3/8" cable would suffice
http://www.engineeringtoolbox.com/wire-rope-strength-d_1518.html

Answer 2

most of what you have shared is common sense stuff[3 cables,45degrees,etc] where can i find the details to determine these things. my need stems from my Solar PV pole mount. i need to calculate the wire size based on a weight,4 panels resting on 2 guy wires. where can i get the equations to determine things like that?