Solar array mounting doubs

[Venezuela Solar]

Hi, where i live sun is up north half of the year and south the other half, we are very close to the ecuador line, so there is good sunshine all the year round but im thinking on mounting a rack of (4) 330 sunpower cells (80 inches long) in a way that i can change the orientation once a year, let me explain, the highest point of my roof is 10 meters, on that point ends the double fall roof, one fall faces north and the other face south, im planning on using one fall to place all modules and using a "triangle" to change their orientation to the opposite face (see pictures).

Would this will be worth it? Or should i just install then horizontal?

Should i place then with the long side parallel to E-W or parallel to N-S axis?

What would you advice? If i go with changing position i would have to go up to the roof 2 or 3 times a year and change the position manually

I will attache screen captures of an app called suncalc where you can see the azimuth and all the details, if i go with tha changing option i would have to know the angle to the horizontal and i dont really know how to calculate it

I would appriciate any help, thanks.

 

[kernel]

I would point that thing south at latitude and fasten permanently. The seasonal variance for optimum array tilt is slight at your latitude and you might pick up 5%.

Caracas was 10° angles 5° outside that will be insignificant.
As is the case near the equator, many panels are tilted just enough to shed water and aid self cleaning. If they are too flat you will get buildup quicker especy at the edges and corners.

 

[SolarRat]

How much wind does your area get? When in the tilted up position, the wind load would be tremendous with an occasional 50mph gust.

 

[svetz]

Personally, I think going flat and adding a few extra panels to make up the loss is cheap enough to avoid the inconvenience of adjusting them all the time. A lot more secure too if you ever get hurricanes.

 

[kernel]

How much wind does your area get? When in the tilted up position, the wind load would be tremendous with an occasional 50mph gust.

My arrays are on east west roof decks and face south at a 35° tilt. Loud and proud! 75mph survival with wind up their skirts no issues.
Follow the mounting engineering guidelines, and you will be fine.

 

[Venezuela Solar]

How much wind does your area get? When in the tilted up position, the wind load would be tremendous with an occasional 50mph gust.

Not to much wind, jan-april are the month with more wind and i think the average is 10-12 mph

 

[Venezuela Solar]

My arrays are on east west roof decks and face south at a 35° tilt. Loud and proud! 75mph survival with wind up their skirts no issues.
Follow the mounting engineering guidelines, and you will be fine.

Are those guidelines in this forum? I really dont understand if i should locate the lenght parallel to north-south or to east-west axis, is there any difference with my current location

 

[kernel]

Face the module south. Portrait (long ways up down) or landscape ( longways horizontal) will matter little. I would do what looks like fits roofing best. Here we look to shed snow and luckily we are way north higher tilt angles. It comes right off!

Nrel and los alamos say landscape produces more power. You will not notice.

 

[kernel]

Are those guidelines in this forum? I really dont understand if i should locate the lenght parallel to north-south or to east-west axis, is there any difference with my current location

The guidelines in the mounting system installation and design manuals. Spans, max loads, tilt, anchoring, all that.
Ironridge is great for this. It will compute full engineering and parts lists.

 

[jasonhc73]

If you want to really go all out. have an adjustable mount.

Sothern Hemisphere
Solar Angle Calculator (90 is horizontal)
Lattitude	-10.000
Panel Length	80
	90
September	79		On the Equinox of March and September, the sun will rise 91° east of due north and set 91° west of due north.
October	71
November	63
December	56		On the December Solstice, the sun will rise 86° east of due north and set 86° west of due north.
January	63
February	71
March	79		On the Equinox of March and September, the sun will rise 91° east of due north and set 91° west of due north.
April	87
May	95
June	102		On the June Solstice, the sun will rise 96° east of due north and set 96° west of due north.
July	95
August	87

But to apply the keep it simple, as stated already, mount the panels at the angle of your latitude. Living within the "tropics" you get to enjoy an abundance of solar and can be sloppy with the angle, it won't make more than 10% difference in the entire year.

Solar Angle Calculator

The solar angle calculator tells you by location the optimum angle to get the best out of your system.

www.solarelectricityhandbook.com

 

[SolarRat]

Not to much wind, jan-april are the month with more wind and i think the average is 10-12 mph

Same here in Florida, but then those pesky hurricanes come thru and....

 

[John Frum]

Like this teeter-totter ?

 

[brewmium]

Personally, I think going flat and adding a few extra panels to make up the loss is cheap enough to avoid the inconvenience of adjusting them all the time. A lot more secure too if you ever get hurricanes.

So, what kind of loss would a flat mount create?

 

[svetz]

So, what kind of loss would a flat mount create?

I don't know... let's ask SAM...

7.8kW @ Key Largo	Annual kWh predicted for 23 panels	Equivalent # panels for ~12190 kWh
fixed tilt (10°)	12,190	23
1 axis tracker (10°)	14,415	20
2 axis tracker	17,896	16

Update: Note that 10° is sub-optimal for the latitude but optimal for winds as it's flat to the roof, so the two-axis tracker takes a big jump.

 

[the_uglydog]

We have the same situation being at 14*N. We ended up building our own adjustable mounts that we change 3 times a year, 2*N, about 15*S and about 30*S. When typhoons look like they will hit, we put them to the 2*N. We use lots of extra panels so we have enough power for everything from about 7AM till 4PM in full sun. We originally had fixed panels that didn't work very well so I designed our setup to get full sun all day plus ventilation under the panels to keep them cooler with correct angles and orientation. There isn't much difference in the output from season to season. That's about it. the dog