How to calculate for shade hours?

[Feisal]

forget the shade hours, you've easily wasted more electrons talking about them, Just total up the good sun hours and you will be close enough.
I've had a couple days this winter, where the clouds were so heavy, I got only a couple watt hours of harvest. Shaded panels produce no usable power in my experience.
(522 wh for the whole day, off a 5Kw array).

Thanks Mike. You are right. Simple and clear.

[J.P.M.]

forget the shade hours, you've easily wasted more electrons talking about them, Just total up the good sun hours and you will be close enough.
I've had a couple days this winter, where the clouds were so heavy, I got only a couple watt hours of harvest. Shaded panels produce no usable power in my experience.
(522 wh for the whole day, off a 5Kw array).

For my part in this, I apologize for sharing some information and opinion I thought correct, and perhaps informative and helpful. In the future I'll do my best to avoid wasting electrons.

[PNjunction]

How to calculate for shade hours? I mean do you just
cut down the insolation hours? IDK. Shade is not like total darkness.

Unless you are designing for a space-mission, here on earth we just throw-away those hours prior to and just beyond the "meat" of solar insolation when calculating, even if there does seem to be *some* minor current flowing.

In the solar-biz, we always try to give ourselves a hedge, and be conservative in design and sometimes, expectations.

[Feisal]

Unless you are designing for a space-mission, here on earth we just throw-away those hours prior to and ....

Thanks PNjunction. Liked your simple explanation.
Cheers.

[Feisal]

The amount of cloud/rain/snow shade is highly dependent on the location, and also dependent on the location. IMO PVWatt does a pretty good job of including this. I did some analysis of the. ... .

Thank you bvmm, sorry for the late response, I overlooked it, my apology. Although I have no clue about the graph you attached, I appreciate your help.

[Feisal]

http://pvwatts.nrel.gov/

I am just saying that PV watts plugs in a 3% shade as default- without proper tools it is difficult calculate shade accurately.
System info is the third page after you type in the address. there is a little picture of a calculator about the middle of that page- next to the line "system losses". click on the calculator and a new box will open. this is where you can adjust the shading amongst other things.

Thanks a lot Scott for your help and guidance.

[diogenes]

I would take a good look at NREL's SAM It actually has a shading model which allows you to define shade objects and their dimensions, a little harder to use than Pvwatts, but I think the effort is worth it.

[J.P.M.]

I would take a good look at NREL's SAM It actually has a shading model which allows you to define shade objects and their dimensions, a little harder to use than Pvwatts, but I think the effort is worth it.

Just takes time to learn, but can give perhaps useful results. Without the learning curve knowledge, design results can be similar to giving a hammer or a butcher knife to a 2 year old.