Spectral correction model upgrades

[mjprilliman]

Pull Request Template

Description

-Add user interface for Detailed PV Spectral Correction Factors
-Choose between three models
-Help messages to indicate if required weather data, cell technology information is available
-Begin to update help documentation
-Cleanup some formatting issues on PV Resource help page
-Add precipitable water to NSRDB calls (TODO: update solar_resource default files to psm v4, add precipitable water in separate issue)

[ include directions for reviewers if necessary- what or how should they test or review ]

Fixes #NatLabRockies/ssc#24

Corresponding branches and PRs:

[[ which branches of wex, lk, and ssc should be built with this PR ]]
same branch for ssc, rest develop

[ link any corresponding PRs in other repos, i.e. NREL/ssc#x ] (NatLabRockies/ssc#1406)

Unit Test Impact:

[ new tests written? ]

[ expected changes in unit tests or speed of tests? ]

[ expected changes in test_results files? ]

Checklist

• [x ] requires help revision and I added that label
• [x ] adds, removes, modifies, or deletes variables in existing compute modules
• adds a new compute module
• [x ] changes defaults
• [x ] I've tagged this PR to a milestone

Reminders- this section can be deleted

[Checking for PySAM Incompatible API Changes]
(https://github.com/NREL/SAM/wiki/PySAM-Incompatible-API-Changes-&-Regenerating-PySAM-Files).

[When do the PySAM files need to be regenerated?]
(https://github.com/NREL/SAM/wiki/PySAM-Incompatible-API-Changes-&-Regenerating-PySAM-Files#when-do-the-pysam-files-need-to-be-regenerated-via-export_config)

[cpaulgilman]

@mjprilliman This looks good! I made a few tweaks to the UI, fixed the UI message logic (I hope), and fixed the documentation merge conflict.

One question: If I run a simulation with the "Air mass and precipitable water" option with a weather file that has no precipitable water data, the simulation finishes with no messages. What precipitable water data does the model use in that case, or should SSC report an error?

[mjprilliman]

@mjprilliman This looks good! I made a few tweaks to the UI, fixed the UI message logic (I hope), and fixed the documentation merge conflict.

One question: If I run a simulation with the "Air mass and precipitable water" option with a weather file that has no precipitable water data, the simulation finishes with no messages. What precipitable water data does the model use in that case, or should SSC report an error?

Good catch, precipitation was defaulting to 0 instead of NaN, which was wrong. Should be working correctly now, and throwing an error message if precipitation data is not present.

[cwhanse]

-Choose between three models

Rather than dig through the files to find out: which three models are offered?

Thanks!