Different orientation to do or not to do?

[bendesa]

Hi all,

I have the following question. I'm curious what you guys think about that. Please let me know. I always appreciate your replies.

Facts:

1 Inverter 100 KW

MPPT number/Max. input strings number 10/20

20 Strings of 18 panels eacht.

I have the following possibilities.

Roof facing North
Roof facing South

I can easily install all panels facing South no problem
I can also choose to install all panels facing North.

Or I can decide to install 10 Strings facing North
and 10 Strings facing South

What would be your choice

Thanks everybody in advance

Kind regards

B

 

[ggunn]

As long as all the modules on a given MPPT input are oriented the same you can have as many orientations as you want - up to the number of MPPTs, of course.

 

[bendesa]

Ok let's make the question more specific. What will result in the highest yield? The location is Indonesia, just South of the Equator.

 

[wwhitney]

Ok let's make the question more specific. What will result in the highest yield? The location is Indonesia, just South of the Equator.

On the equator, assuming equal roof slopes, and no calendar variation in atmospheric effects like cloudiness, the annual production of a panel on the North facing roof and a panel on the South facing roof will be equal.

Moving south from the equator, there will start to be an advantage for the north facing panels. But depending on the value of "just south" I would expect it to be negligible.

You can do some simple modeling of this with PVWatts.

Cheers, Wayne

 

[ggunn]

On the equator, assuming equal roof slopes, and no calendar variation in atmospheric effects like cloudiness, the annual production of a panel on the North facing roof and a panel on the South facing roof will be equal.

Moving south from the equator, there will start to be an advantage for the north facing panels. But depending on the value of "just south" I would expect it to be negligible.

You can do some simple modeling of this with PVWatts.

Cheers, Wayne

Will PVWatts even work for areas outside the US? I think it only links to U.S. NREL weather data.

 

[wwhitney]

Will PVWatts even work for areas outside the US? I think it only links to U.S. NREL weather data.

I got as far as entering "Indonesia" into the location and getting a latitude/longitude, but didn't do a full run.

Not sure how PVWatts uses weather data, on what time scale. Anyway a comparison without weather data is still useful. I guess you could have a situation just south of the equator where north facing panels are slightly better without considering weather, but then if the weather is cloudier between March and September, south facing panels end up doing better.

Cheers, Wayne

 

[ggunn]

I got as far as entering "Indonesia" into the location and getting a latitude/longitude, but didn't do a full run.

Not sure how PVWatts uses weather data, on what time scale. Anyway a comparison without weather data is still useful. I guess you could have a situation just south of the equator where north facing panels are slightly better without considering weather, but then if the weather is cloudier between March and September, south facing panels end up doing better.

Cheers, Wayne

I didn't think it would run a simulation without weather data.

 

[wwhitney]

I didn't think it would run a simulation without weather data.

Well, when I enter the location (-80, -80) (an attempt at latitude, longitude), I get an error message about no weather stations within 2000 miles. But if you enter Indonesia, it picks a weather station on Borneo, and zooming out, it has 3 weather stations on Borneo.

So apparently the data set is not limited to the US, but presumably it is much denser in the US.

Cheers, Wayne

 

[ggunn]

Well, when I enter the location (-80, -80) (an attempt at latitude, longitude), I get an error message about no weather stations within 2000 miles. But if you enter Indonesia, it picks a weather station on Borneo, and zooming out, it has 3 weather stations on Borneo.

So apparently the data set is not limited to the US, but presumably it is much denser in the US.

Cheers, Wayne

Did you simulate an array and get some results?

 

[wwhitney]

Did you simulate an array and get some results?

You know, instead of asking all these second-guessing questions, you could have tried it yourself in less time.

Yes, of course I did.

Wayne

 

[ggunn]

You know, instead of asking all these second-guessing questions, you could have tried it yourself in less time.

Yes, of course I did.

Wayne

Why? You answered my question.

You could have just told me that you tried it and it worked, you know.

 

[ggunn]

Why? You answered my question.

You could have just told me that you tried it and it worked, you know.

So don't keep me in suspenders; did the orientation make a difference or not?

 

[wwhitney]

So don't keep me in suspenders; did the orientation make a difference or not?

Sorry, your second guessing quota has been exceeded, you'll have to try it yourself. : - )



(I actually didn't do any comparative runs, just wanted to see if PVWatts would work for locations outside the US. Plus I'm happy with my understanding of the solar geometric effects, and not too interested in the vagaries of weather effects.)

Wayne

 

[ggunn]

Sorry, your second guessing quota has been exceeded, you'll have to try it yourself. : - )



(I actually didn't do any comparative runs, just wanted to see if PVWatts would work for locations outside the US. Plus I'm happy with my understanding of the solar geometric effects, and not too interested in the vagaries of weather effects.)

Wayne

I don't know what you mean by second guessing. I wasn't trying to catch you on anything; I didn't know whether it would work or not. I do know that several years ago when I trued it for a location in Oman with an earlier version of PVWatts, it didn't work.

 

[wwhitney]

I do know that several years ago when I trued it for a location in Oman with an earlier version of PVWatts, it didn't work.

That's interesting--now if you enter Oman, it tells you the closest "Solar Resource Data Site" is in Abu Dhabi, UAE, 278 miles from the (presumed) geographical center of Oman. And the results you get are the same as if you enter Abu Dhabi, I assume it is just using the location of Abu Dhabi either way, rather than using the location of Oman with the weather data from Abu Dhabi, when you enter Oman.

I don't know what you mean by second guessing.

I mean that while I didn't tack "and PVWatts runs fine" on the end of post #8, since I clearly went back to the PVWatts website again, it was implicit. So post #9 was either badgering or based on the possibility of my being extraordinarily careless. Perhaps you've forgotten that it literally takes 10 seconds to search PVWatts, go to the site, enter Indonesia (or Oman), and click through to see results for their default array..

Wayne

 

[ggunn]

I mean that while I didn't tack "and PVWatts runs fine" on the end of post #8, since I clearly went back to the PVWatts website again, it was implicit. So post #9 was either badgering or based on the possibility of my being extraordinarily careless. Perhaps you've forgotten that it literally takes 10 seconds to search PVWatts, go to the site, enter Indonesia (or Oman), and click through to see results for their default array..

Wayne

No badgering or accusation of carelessness was intended, I assure you. Lighten up; it's Friday!

 

[GoldDigger]

No badgering or accusation of carelessness was intended, I assure you. Lighten up; it's Friday!

And, fortunately, Friday the 13th fell on Monday this month.