Bifacial-radiance

A sign error in calculating the tracker angle resulted in a 1-hour offset between the calculated tracker angle and actual tracker angle. This resulted in over-estimates of bifacial gain. v0.2.2 fixes this problem. Unit tests are also introduced. These can be run from the command line by running 'pytest' in the repository root folder.

Model intercomparisons look favorable with PVSyst, [SAM (beta)](https://sam.nrel.gov/sites/default/files/content/public_releases/sam-beta-windows-2018-8-29.exe) and [bifacialvf](https://github.com/nrel/bifacialvf) for fixed-tilt conditions.


Single-axis tracking also checks out within 10%-15% (relative) for rear irradiance.


Updated TMY3 support - allows reading in .csv files in the TMY3 format.
No longer using pyepw to read in EPW files - now using readepw.py file from S. Quiolin from the pvlib forums.
Improved stability should result.

A geometry error was resulting in over-estimation of rear irradiance for single-axis tracked systems. Version 0.2.0 has fixed the problem.

A minor change is made to allow orientation azimuths in all directions from 0 to 360 degrees. This will help with modeling southern latitude systems.

Update to 1-axis tracking and validation

There was an important update to how 1-axis tracking .csv weather files are saved and passed to gencumulativesky.

Now we have favorable front irradiance comparison with PVSyst, SAM and [bifacialvf](https://github.com/nrel/bifacialvf)



Favorable rear irradiance comparison with [bifacialvf](https://github.com/nrel/bifacialvf)




1-axis tracking examples
See /docs/1Axis_tracking_example.ipynb for usage examples.
See /docs/1Axis_Radiance_VF_comparison.py for a comparison with our partner project - [BifacialVF (view factor model)](https://github.com/nrel/bifacialvf)

`RadianceObj.set1axis(metdata, axis_azimuth, limit_angle, angledelta, backtrack, gcr)`: import weather file and parse into sub-files based on the tracker angle during those times. Return: trackerdict (dictionary with relevant tracker-specific data)
`RadianceObj.genCumSky1axis(trackerdict)` : Generate cumulative sky data for each tracker angle
`RadianceObj.makeScene1axis(trackerdict, moduletype, sceneDict, nMods, nRows )` : Generate .rad file geometries for each tracker angle
`RadianceObj.makeOct1axis(trackerdict)` : Generate octfiles incorporating all of the above for each tracker angle



PREREQUISITES (Step 0):
This software requires the previous installation of [RADIANCE](https://github.com/NREL/Radiance/releases) .

Make sure you add radiance to the system PATH so Python can interact with the radiance program

If you are on a PC you should also copy the [Jaloxa radwinexe-5.0.a.8-win64.zip executables](http://www.jaloxa.eu/resources/radiance/radwinexe.shtml) into `program files/radiance/bin`:

STEP 1: Install and import bifacial_radiance

- clone the bifacial_radiance repo to your local directory or download and unzip the .zip file
- navigate to the \bifacial_radiance directory using anaconda command line
- run `pip install -e . ` ( the period . is required, the -e flag is optional and installs in development mode where changes to the bifacial_radiance.py files are immediately incorporated into the module if you re-start the python kernel)

STEP 2: Move gencumulativesky.exe
Copy gencumulativesky.exe from the repo's `/bifacial_radiance/data/` directory and copy into your Radiance install directory.
This is typically found in `/program files/radiance/bin/`.

STEP 3: Create a local Radiance directory for storing the scene files created
Keep scene geometry files separate from the bifacial_radiance directory. Create a local directory somewhere to be used for storing scene files.

STEP 4: Reboot the computer
This makes sure the PATH is updated

New functionality: Single-axis tracking capability

See /docs/1Axis_tracking_example.ipynb for usage examples.
See /docs/1Axis_Radiance_VF_comparison.py for a comparison with our partner project - BifacialVF (view factor model)

`RadianceObj.set1axis(metdata, axis_azimuth, limit_angle, angledelta, backtrack, gcr)`: import weather file and parse into sub-files based on the tracker angle during those times. Return: trackerdict (dictionary with relevant tracker-specific data)
`RadianceObj.genCumSky1axis(trackerdict)` : Generate cumulative sky data for each tracker angle
`RadianceObj.makeScene1axis(trackerdict, moduletype, sceneDict, nMods, nRows )` : Generate .rad file geometries for each tracker angle
`RadianceObj.makeOct1axis(trackerdict)` : Generate octfiles incorporating all of the above for each tracker angle