PV array placement

[electricalperson]

can anybody with PV experience help me with this? I am having trouble understanding how too properly lay out PV panels. Basically for example, PV panels are on a flat roof and tilted. The book explains how to lay it out but it seems to be a little over my head. They are talking about solar altitude angles, solar azimuth angles, array azimuths and profile angles. It seems complicated and i do not understand it.

Also when they talk about Latitude, are they talking about latitude like on a map?

here is the text from the book.

"An array consisting of multiple rows of tilted modules is to be installed on a flat rooftop at 40 degrees N latitude. The rows must be spaced to avoid shading each other between 9 am and 3 pm during the winter solstice. At these times, the solar altitude angle is 14 degrees and the solar azimuth is 42 degrees. Also, due to the orientation of the building, the rows are to be installed facing 10 degrees west of due south. Therefore, the azimuth angle between the solar azimuth and array azimuth is 52 degrees at 9 am (42 degrees + 10 degrees) and 32 degrees at 3 PM (42 - 10) Both azimuth angle circumstances may need to be calculated to determine wich has the greater effect. If the module tilt results in a row height of 1.5' then what is the minimum distance for these circumstances?"

I dont know if i am over thinking it, I had trig in school but did not do too well and that was almost 10 years ago.

The formula is d = h x cos@ / tan&

@ = azimuth angle between solar and array azimuth in degrees

& = solar altitude angle


I am taking a course and everybody in the class is confused about this stuff

 

[LEO2854]

can anybody with PV experience help me with this? I am having trouble understanding how too properly lay out PV panels. Basically for example, PV panels are on a flat roof and tilted. The book explains how to lay it out but it seems to be a little over my head. They are talking about solar altitude angles, solar azimuth angles, array azimuths and profile angles. It seems complicated and i do not understand it.

Also when they talk about Latitude, are they talking about latitude like on a map?

here is the text from the book.

"An array consisting of multiple rows of tilted modules is to be installed on a flat rooftop at 40 degrees N latitude. The rows must be spaced to avoid shading each other between 9 am and 3 pm during the winter solstice. At these times, the solar altitude angle is 14 degrees and the solar azimuth is 42 degrees. Also, due to the orientation of the building, the rows are to be installed facing 10 degrees west of due south. Therefore, the azimuth angle between the solar azimuth and array azimuth is 52 degrees at 9 am (42 degrees + 10 degrees) and 32 degrees at 3 PM (42 - 10) Both azimuth angle circumstances may need to be calculated to determine wich has the greater effect. If the module tilt results in a row height of 1.5' then what is the minimum distance for these circumstances?"

I dont know if i am over thinking it, I had trig in school but did not do too well and that was almost 10 years ago.

The formula is d = h x cos@ / tan&

@ = azimuth angle between solar and array azimuth in degrees

& = solar altitude angle


I am taking a course and everybody in the class is confused about this stuff

This is what they mean by latitude...

 

[jaggedben]

I dont know if i am over thinking it ...

I think you are either over thinking it, or you just haven't realized that they expect you to have a calculator with trig functions. Once you calculate 'cos@' and 'tan&', and write them into the formula, it's a very simple math equation.

Finding out the solar angle for a given latitude and time is another matter. I think most of us would need a table for that.

 

[ggunn]

can anybody with PV experience help me with this? I am having trouble understanding how too properly lay out PV panels. Basically for example, PV panels are on a flat roof and tilted. The book explains how to lay it out but it seems to be a little over my head. They are talking about solar altitude angles, solar azimuth angles, array azimuths and profile angles. It seems complicated and i do not understand it.

Also when they talk about Latitude, are they talking about latitude like on a map?

here is the text from the book.

"An array consisting of multiple rows of tilted modules is to be installed on a flat rooftop at 40 degrees N latitude. The rows must be spaced to avoid shading each other between 9 am and 3 pm during the winter solstice. At these times, the solar altitude angle is 14 degrees and the solar azimuth is 42 degrees. Also, due to the orientation of the building, the rows are to be installed facing 10 degrees west of due south. Therefore, the azimuth angle between the solar azimuth and array azimuth is 52 degrees at 9 am (42 degrees + 10 degrees) and 32 degrees at 3 PM (42 - 10) Both azimuth angle circumstances may need to be calculated to determine wich has the greater effect. If the module tilt results in a row height of 1.5' then what is the minimum distance for these circumstances?"

I dont know if i am over thinking it, I had trig in school but did not do too well and that was almost 10 years ago.

The formula is d = h x cos@ / tan&

@ = azimuth angle between solar and array azimuth in degrees

& = solar altitude angle


I am taking a course and everybody in the class is confused about this stuff

The azimuth angle is just the angle relative to true north, so an azimuth of 180 degrees is due south. These are true as opposed to magnetic measurements, i.e. relative to the poles on a globe, which is different from where a compass points. That difference changes with where you are, and that difference is called declination. Here in Austin it's about +4.5 degrees; here's a website that will provide it to you http://www.magnetic-declination.com/

Altitude angle is the apparent height of the sun in the sky. At solar noon on the equinoxes, the altitude angle is equal to 90 degrees minus your latitude - latitude is the number of degrees off the equator. Hence, at a point on the equator at that time on those days, the sun is directly overhead (90 - zero) and at the poles the sun is bisected by the horizon (90 - 90).

To see the differences changing the array azimuth and tilt will make on the output of a PV system anywhere in the US, go to PVWatts (http://www.nrel.gov/rredc/pvwatts/grid.html) and plug in some numbers. You can also generate charts that show the position of the sun in the sky at any time of day on any day of the year at any location on the planet by going to this site: http://solardat.uoregon.edu/SunChartProgram.html.

Good luck with your class.