TRY for photos

http://www.solarray.com/TechGuides/Racks_T.php

 

Power Sources

Racks & Mounts

Mounting Frames for Solar Modules:

The type of rack you need depends on where the solar panels will be mounted. They are most often either mounted on top of a pole or on a roof. Top-of-pole mounts can be either stationary or trackers that follow the sun's movement across the sky. Sometimes solar panels are mounted on a rack on the ground.

Roof Mounts come in two basic types: flush and tilt-up.
Flush mount roof racks keep the modules down on the roof, just a few inches above the roofing material. This is the least obtrusive visually, and therefore is popular in suburbs and higher-density residential areas. The major drawback of this mounting system is that the solar array has to face whichever direction the roof faces (which is usually not due south) and has to lie at the angle of the roof's pitch (which is usually not the optimal angle). What this means in real terms is that you don't get as much power out of your solar panels as you could. They also tend to create higher temperatures for the panels, which also slightly lowers their output. For this type of installation we use either Unirac SolarMount or Conergy SunTop racks.

Tilt-up racks can be angled up off a roof's pitch to the optimal angle for your area and can be seasonally adjusted. They are more visually obtrusive than flush mount racks, but in most instances they allow the panels to produce more energy. Tilt-up racks can also be turned to face due south on a roof that faces off south, again increasing energy production. Doing this, however, does look awkward.

Ground mounted PV arrays can use the same racks as roof mounted tilt-up arrays.

We usually prefer not to mount on roofs because of the potential for leaks, difficulty of maintenance and over heating. However, a roof mount is generally more secure from theft or damage, and sometimes offers the best access to the sun.


Our prefered type of array mount is the Top-of-Pole rack. This type allows for easy seasonal adjustments for tilt angle, is easy to install, keeps us installers off of roofs (with the associated liability issues),and precludes roof penetrations (with the associated leak potential). As compared to ground mounts, a top-of-pole rack puts panels up into a position less prone to damage from lawnmower-thrown rocks, etc. There are several manufacturers of top-of-pole racks that don't meet our standards of stability and ease of use. Direct Power & Water makes the best on the market -- we use them for almost all of our pole mount installations.

We sometimes custom build top-of-pole racks to accomodate older panels or odd combinations of panels.


Trackers are top-of-pole mounts that use electronic sensors and motors to automatically follow the sun's path. During cloudy weather they face the brightest part of the sky to maximize the array's output. Trackers can increase an array's power production by 10-50%, and are particularly effective in array direct water pumping situations. (We no longer install or recommend passive trackers, partially due to their tendency to flop around in the wind--which we have plenty of here in the Southwest).

Wattsun trackers, the only active trackers we recommend, come in single and dual-axis models. Single-axis trackers follow the sun's path from east to west, but they don't track the sun's seasonal changes, as the sun's angle gradually rises in the sky from winter to summer and falls again from summer to winter. With single-axis trackers, seasonal changes must be made manually, in the same way as one would with a fixed top-of-pole rack. Single-axis "tilt and roll" and "azimuth" type trackers are available. Dual-axis trackers follow the sun's seasonal changes, as well as the daily rising and setting of the sun.

As with all motor-driven technology, reliability can be an issue with trackers. Though Wattsun trackers provide many years of trouble-free service, they do require occasional service calls. When a tracker malfunctions, it can leave the array pointing toward the wrong part of the sky, leaving its owner with a shortage of power.

The added cost vs. performance boost of using a tracker usually adds up only with larger arrays. With smaller arrays, it is usually more cost effective to simply buy an additional panel or two.

 

Solar-tech Russ demonstrates the adjustability of a SolarRay manually trackable array mount. This we installed outside of El Rito, NM.

In response to customer requests we have developed the Manually Trackable top-of-pole rack. With this, an array can turned to face the sun if more power is needed in the morning or evening, and the
problems usually associated with trackers are avoided. Adjusting the direction the rack faces is easily accomplished with a hand crank. When additional gain isn't needed in the early or late hours of the day, the rack can simply be set to due south and left alone. It will then function as a regular top-of-pole rack. We can fabricate these to accomodate any size array or combination of panels.


Do-it-yourselfers commonly respond to the problem of mounting solar panels by constructing their own wood racks. Telling you that this is a bad idea isn't simply an attempt on our part to sell more products -- it truely is a bad idea. Improper mounting and shoddy wooden rack construction, combined with wind, is the #1 cause of damage to solar panels -- and we have seen many such instances. However, we have never seen panels that were properly mounted on high quality racks sustain wind damage. The problem with wood is that it rots -- even pressure treated wood, even in a dry climate such as ours, in New Mexico. Another major problem with wood is that it warps and twists in the weather, putting stress on fasteners and panels alike (snapped drywall screws is a common sight on wooden racks). In five years that beautiful weekend project could be a major hazard to your investment. But problems with rack construction are not limited to wood -- we have seen some of the craziest metal contraptions designed to hold solar panels you can imagine (complete with duct tape, bailing wire, and concrete blocks). Trying to save a few hundred dollars by putting much more expensive solar panels at risk is false economy. Modules cost a lot of money! A quality rack should always be considered a necessary part of a solar system!

 

 

Per Solar Ray.com      http://www.solarray.com/TechGuides/Racks_T.php