Questions about the annual irradiance component (LBT 1.5)

[LaFleur]

Dear @chris, sorry if I bother you

I have a couple of doubts regarding the Annual Irradiance component (LBT 1.5)

Points 1
I noticed that by simulating the “hoy” where the sun is down (p.e. 1 January from 0:00 to 7:00), the component give a error, without any results

but if I use a “hoy” in which at that time the sun will rise (8:00) I will have (I think correctly) a 0 W/m² as value (In this case the sun rises at 8.5, according the sun-up-hours text file)

Points 2
In the annual analysis, I found negative values out from the results output

Points 3
the res_direct, take care of the w/m² only of the direct sun beam, excluding the global and diffuse illuminance?

In this case, also the “visible” input, decides if the annual irradiance takes into account only of the direct solar rays, for the all output result (peak, average and radiation)??

Thanks for all and a good Weekend

[chris]

Hi @LaFleur ,

Yes, the recipe is not designed to be run with completely nighttime Weas. If there’s no daytime hours, the simulation is designed to fail. We can technically implement something to let the calculation proceed and give you a bunch of zeros but I personally would rather have a failure in this case since the only situations where I would be simulating a nighttime Wea are ones where I messed up the input and I would want to be made aware of it.

The negative values should go away if you use better radiance parameters. There was also a bug in the older version of LBT that would yield more extreme negative values. But you shouldn’t be able to get them in LBT 1.5 if your parameters are good enough and, if you do get them, they should be pretty close to zero.

@LaFleur

the res_direct, take care of the w/m² only of the direct sun beam, excluding the global and diffuse illuminance?

I’m not sure I understand the question but I think the answer is “yes”. The res_direct is only the irradiance directly from the disc of the sun without anything from the rest of the sky or any ambient bounces.

@LaFleur

In this case, also the “visible” input, decides if the annual irradiance takes into account only of the direct solar rays, for the all output result (peak, average and radiation)??

I don’t know what you’re asking here. The visible_ input changes all of the irradiance results to be for the visible part of the spectrum as opposed to the entire solar spectrum (hopefully that answers the question).