"net" columns are empty in ResStock timeseries

[rajeee]

Describe the bug
Buildings that don't have PV will not have PV and "net" output columns in the timeseries. This can lead to errors downstream when sum or other aggregations are calculated since the empty columns are interpreted as zero. Interpretation of 0 is correct for the PV energy consumption columns but will be incorrect for the "net" columns such as "fuel_use__electricity__net__kwh", "energy_use__net__kbtu" etc.

To Reproduce
Look at any existing ResStock run.

Expected behavior
The concatenated timeseries files uplaod to s3 will have a correct "net" column values even if the raw timeseries csv from the simulation doesn't.

Additional context
This is causing problem for the EUSS processing.

[shorowit]

I think we can make this change in OS-HPXML. NREL/OpenStudio-HPXML#1676

[rajeee]

Change made in OS-HPXML.