I'm using the DISC model to convert GHI data points from a weather station into a DNI value, then use those two values to feed into the DNI-GHI to DHI model. (
Is it Possible to Estimate GHI or DHI from only DNI?
)
The issue is that the model (both in my code and in the spreadsheets) occasionally generates a negative value for one of the component values. I've seen references to the same problem in other forum posts
(
TMY3 Weather Data Errors -- One Year Works, Another Doesn't
)
The consensus solution seems to be to use values from before and after in the model, however the tool I've created is attempting to do single instantaneous snapshot comparisons of weather data versus reported production data. I can zero out the values, and then also zero out the estimated production value but of course that makes the comparison irrelavent.
So the long winded question is if there is anything else that can be done with these, or has anyone determined if there are certain conditions that break the model? Any suggestions would be appreciated.
Thanks,
Mikkel
