Describe the bug

If a user assigns a negative tilt for a 1 axis tracking system it appears to be treated as a positive tilt.

To Reproduce

Steps to reproduce the behavior:

1. Start a detailed PV model
2. In System Design, select "1 Axis" and assign a negative tilt value (e.g., -10)
3. Simulate
4. See the notice that describes the tilt as positive
5. Compare results (energy, surface tilt and surface azimuth) with a similar case using a positive tilt and see that results are identical.

Expected behavior

One of the following, or similar:

• Issue an error message about negative values being invalid
• Issue a notice message about negative values automatically being converted to positive
• Model the system with the described geometry but with a notice (e.g., model tilt = -10 and azimuth =180 as tilt = 10 and azimuth = 0)

Screenshots

Notice that occurs when assigning a negative tilt (note that tilt angle in the notice is positive):

Results with tilt = 10, azimuth = 180:

Results with tilt = -10, azimuth = 180 (same as above, not what I expected):

Results with tilt = 10, azimuth = 0 (what I expected -10, 180 to look like):

Inputs browser for reference:

Operating System and Version

• OS: Windows
• Version: SAM 2021.12.2 r2 [e.g. SAM 2020.2.29 r3]

Tagging @kanderso-nrel and @kurt-rhee, since they brought up this issue here pvlib/pvlib-python#1471.