Mounting Structures

The mounting structure is the supporting structure that holds the solar panels or arrays of solar panels to the ground.


Mounting structures support solar panels on the ground, or on the rooftops.

Solar panels work best when they recieve as many hours of sunlight as possible and are mounted at an optimal tilt and facing the south. There are several ways to mount solar panels to maximize solar exposure and energy production.

1. Panels need to be attached to the roof or to the ground. The panels themselves cannot be directly attached to the ground owing to their structure, and hence they need a separate mounting structure.
2. Solar panels need a secure fastening to the roof or ground to protect against winds. Mounting structures do this function. 
3. Solar panels also require protection against water and other elements that gather on the ground or on the roof.
4.  In case of rooftop solar, the roof might not have a suitable inclination to get the maximum from sunlight. Having mounting structures at a suitable angle can tilt the solar panels at an optimal angle. 
5. You need some space between the solar panels and the ground for the cables etc. In addition, you need space for repairs and maintenance of the panels.

What are the mounting structures made of?
Mounting structures are usually made of steel, which is galvanised for protection against corrosion. Lightweight structures could also be made from Aluminium.

Do the mounting structures require maintenance?
Typically, mounting structures require little or no maintenance, unless these structures come along with solar trackers.


How much do mounting structures weigh?


There is a wide variety of mounting structures available, and hence it will be difficult to put down a specific number. However, in general, one can expect really lightweight mounting structures from Aluminium to weigh as low as 25 Kg /kW to sophisticated stainless steel structures that could weigh as high as 200 Kg/kW. The mounting structure area surely is an evolving field and one can expect many improvisations in design and materials in the coming years.

Are there lightweight mounting structures?

Yes. A number of companies offer lightweight mounting structures made of Aluminium, though it is not entirely clear which of the two structures – Aluminium or Steel – is better. It is quite possible that lightweight mounting structures are more suitable for specific types of roofs or land that might not require the durability of steel structures.

How much do mounting structures cost?
Typically, mounting structures cost about 10% of total system cost for large solar power plants and about 15% for smaller power plants.

What are solar mounting structures?

Mounting systems can often be the most complicated portion of a solar PV system installation as they form the foundation of the system – they protect the modules, the roof and people over a lifetime that can exceed 25 years. Thus, it can be seen that solar mounting structures are far more critical to the performance of solar power plants than most people think.

Why are they critical?
Solar panels perform at their best when they face perpendicular to the sun’s rays. But the sun’s position with respect to the solar panel changes throughout the day and over the seasons.
There are times when the direction of your roof may not be facing the optimal direction for maximum production. In such as scenario, rooftop mounting systems are utilized to position the panels in the required direction.

What benefits do they offer?

1. Maximizes energy production They orient the panels to receive maximum solar energy possible. Appropriate layout of arrays becomes very important for optimized cable length as well as optimized energy production. 
2. Enhances stability of the module They provide stability to the module/panel and hold them stable in the areas of strong winds. 
3. Fortification Rooftop mounted solar panels protect your roof from adverse weather conditions and, wear and tear. This, in turn, increases the lifetime value of your roof and structure.

A guide to mounting racks for solar panels (PV)

Speaking about solar PV systems most people usually refer at first to solar panels, secondly to inverters and batteries, thirdly to charge controllers.

But what about the structures you need to mount your system on a roof or a tracking systems? The correct and proper choice of the mounting racks (also called: mounting structures) for your solar system project is very essential in terms of the overall production, efficiency and lifetime of your solar panels.

Since it is a costly investment, the choice of mounting racks should not be disregarded as a minor consideration if purchasing solar systems or mounting solar modules.

Solar modules need to be secured, mounted and tightened on a very stable and durable structure, protecting the array against impacts from snow, wind, hail, rain and even minor earthquakes.

They are either mounted on ground, on roofs or on poles. In the solar market there are five basic types of mounting structures of which four a fixed-angle types (a-d) and one variable-angle type (e):

a) roof mounted racks

b) ground mounted racks

c) top-of-pole mounted racks

d) side-of-pole mounted racks

e) tracking system mounted racks


Roof mounted racks typically keep the wire run distances between the solar array and the battery bank or inverter to a minimum, but require roof penetrations and run danger of causing roof leakages, thus the roof must be well sealed.

Another disadvantage of roof mounted structures can come up if the roof orientation and angle is not optimal, thus wasting lots of potential energy that your system could generate.

For optimal system efficiency using a roof mounted structure you need to ensure that there is no shadow from trees or other buildings in the optimally free airflow path of your solar panels.

Moreover, according to 690-5 of the US National Electrical Code-NEC they require expensive ground fault protection (GFP).

Ground mounted racks do not require GFP, but need a precise foundation setup. Ground mounted structures run danger of being exposed to vandalism, accumulation of dirt, leaves and snow at the bottom of the array.

Therefore, ground-mounted racks are only recommended for secure locations preferably in clean and stable environments (with few snow or dirt on-ground).

Top-of-pole mounted racks are structures where mounting poles are secured into the ground and tightened with concrete and the solar module is mounted on the top of the poles.

The advantage is that it is rather not exposed to vandalism and accumulation of dirt, leaves and snow, but are not easy to clean.



Side-of-pole mounted racks are normally used for solar systems that comprise a small number of modules. They are particularly used for remote lighting systems that already come with a pole where they can be easily attached to.

Tracking system mounted racks can be used for all kinds of solar tracking systems as well as solar water pumping systems, allowing for a maximum of sun radiation that can be used for generating electricity.

They especially pay-off in hot climates. There are two different types of mounted structures for tracking systems, that are one-axis and two-axis.

The one-axis trackers are designed to track the sun movement from the east to the west while the two-axis systems track the sun's daily and seasonal course and are overwhelmingly used with PV concentrator systems.



Mounting rack material
Mounting racks can be made of different kinds of materials. Do not forget to ask your manufacturer about the material of his mounting structures in order to avoid wrong and post-project expensive choices.

The majority of manufacturers of mounting racks use Aluminum. It is not only low weight - thus decreasing weight pressure on the roof, pole or tracking system - but also corrosion-resistive, strong and compatible to the solar module frames of many manufacturers that are mostly made of Aluminum.

Another choice can be mounting structures made of stainless steel. Although stainless steel racks are very strong and resistant against environmental impacts such as hail, snow, rain etc. and can last for ages, they are nevertheless an expensive investment.

Wood-made mounting racks are cheap and easy to work, but are weak in consistence and bound to fail quickly particularly in wet environments.

Plastics-made mounting racks are also cheap, but not the optimal choice in terms of statics and lifetime. Like wood-made mounting racks , they may burn or even break if pressure on the solar panel (e.g. snow) is too high.

Last but not least, iron-made mounting racks are also easy to work and slightly more expensive than wooden racks , but quickly fall victim to corrosion and are not recommendable in wet environments.

Conclusion
If you purchase mounting structure you can usually choose from a wide range of manufacturers and a bunch of standard mounting structures.

Since every solar project and location requirement is different, it would be optimal to purchase a customized mounting rack, but they are expensive as compared to the standard solutions.

Thus it is advisable to do detailed calculation in terms of the mounting racks, taking into account the project site, sun radiation and mounting material that is proper for the project site and do efficiency/ pricing comparisons.

Sometimes, purchasing a customized solution may - despite possible efficiency losses with standard structures - may not be worth the investment.

If buying a customized solar system, optimally a complete one if you are an end-user that includes panels, inverters, batteries, charge controller and mounting rack, good and serious companies will provide you with a system design that in view of your individual project requirements includes customized mounting structures that also come with proper certification (ISO, CE, TUV etc.).


Photovoltaic mounting systems (also called solar module racking) are used to fix solar panels on surfaces like roofs, building facades, or the ground.These mounting systems generally enable retrofitting of solar panels on roofs or as part of the structure of the building called building integrated photovoltaic s (BIPV).

Types of Mounting Systems
1.Flush to Roof Racking System or InRoof System:

A flush photovoltaic system requires the panels to be fitted flush to the roof of your property making it one of the most popular ways of fitting PV solar panels because it will provide the most solar power and once installed, it looks better than means of installation. In roof systems look as if they fit seamlessly to the roof as they require a portion of the roof tiles to be removed allowing the solar panels to be fitted to the roof in their place. As well as having the panels fitted it is necessary to also have an inverter which will convert the power from DC into AC power that can be used in the house.

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 Unirac SolarMount racks.


The PV panels sit flush with the surrounding roof tiles using a special mounting system which removes the tiles underneath the PV panels.  This can be a more attractive option but is also slightly more expensive than the standard on-roof system.

Solar Roof Mounts are used to install solar panels on an inclined or flat roof. These mounting structures are usually made of aluminum or stainless steel.

What are Solar Roof Mounts?
Solar Roof Mounts, as the name suggests, is a mechanism with which the PV Panels can be installed upon the roof.


In an area which is populated with short trees or buildings, this may be the best possible installation. This could be achieved either by running aluminum or stainless steel rails along the roof and then attaching the panels to those rails, or by placing multiple brackets on the roof top, at certain distances, and attaching the panels to those brackets.

Disadvantage Solar Roof Mounts
Roof penetration
One disadvantage of using Roof Mount structures is that it requires penetration through the roof which may result in leaks and dampness.

Roof mounted structures typically keep the wire run distances between the solar array and the battery bank or inverter to a minimum, but require roof penetrations and run danger of causing roof leakages, thus the roof must be well sealed.

Roof loading capacity
Also, there is only a certain number of panels which you could install upon the roof depending upon the loading capacity and structural strength of the roof.

Roof orientation
Another disadvantage of roof mounted structures can come up if the roof orientation and angle is not optimal, thus wasting lots of potential energy that your system could generate.

For optimal system efficiency using a roof mounted structure you need to ensure that there is no shadow from trees or other buildings in the “optimally free “ airflow path of your solar panels.


Moreover, according to 690-5 of the US National Electrical Code-NEC they require expensive ground fault protection (GFP).
source:  http://sinovoltaics.com/

2.Tilt Up Racking Sysem:

Fixed Tilt Solar Racking System is applicable to install the usual framed module to tilt a certain angle with the roof. The solar system can be a fixed angle or adjustable such as 10~15 deg, 15~30 deg and 30~60 deg for your requirement. The special extruded aluminum rail, the tilt-in module, the clamp kit and the round leg can be high pre-assembly and make the installation easy and quick to save your labor cost and time. The customized length can eliminate the weld and cut onsite to keep the high anticorrosive performance, the structure strength and the appearance.

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.

source:http://www.gracesolar.com/

3.Ballast Racking System:
Ballast mounts rely solely on the weight of the array, racking system and additional material, like concrete pavers, to hold the array to the roof. Their biggest advantage is the lack of roof penetrations. This does not eliminate the need for working with a roofing contractor, but it can significantly reduce the coordination required between the roofer and the PV installer. These arrays can generally be installed while maintaining the roof warranty. But in order to do so, the installation must be coordinated with the original roofer or an approved representative for the roofing manufacturer. Ballasted systems need to be carefully analyzed due to the increased roof loading imposed by the array. Also, many ballasted systems will be limited to a pitch of 20° or less to minimize wind uplift forces.

Solar panel arrays are well suited for placing on flat roofs of large buildings and the mounting of these panels can be performed a number of ways, roof penetrating and ballasted. Roof penetrating mounting systems are not desirable due to the high labor costs and voiding the manufacturer's warranty. Ballasted mounting systems are held on the roof using weights, are simple to install and do not void the roof warranty.
Occasionally, solar panels are placed in a yard or field which are mounted on either a pole or upon ground-mounted racks. Although these types of systems have additional associated costs, it is sometimes the best option if the roof in question does not have good orientation, does not have adequate sun exposure, or is structurally unsuitable for holding the solar array. Ground-mounted PV systems typically include extra costs for concrete pads, digging trenches, additional conduit, wire, design costs, and additional permitting or zoning costs.
4.Top of the pole Racking system:

Top-of-pole mounts are structures where mounting poles are secured into the ground and tightened with concrete and the solar module is mounted on the top of the poles.

Advantages Top-of-Pole Mounts

The advantage is that it is rather not exposed to vandalism and accumulation of dirt, leaves and snow. These types of mounting structures can hold between 1 and 20 solar panels per pole.

The inclination of the mount can usually be adjusted manually according to the seasons. Some top-of-pole mounts have a tracker included.

Disadvantages Top-of-pole Mounts

Cleaning can be an issue as the panels are mounted way above ground. Maintenance crew needs special equipment to reach and clean the panels.

Winload capability Top-of-pole mounts
Similar to the Side-of-pole mounts,  you will need to take into account the windload capabilities of the pole and top-of-pole mount that you’re installing.

Most mounts are made to withstand winds up to 150km/u. However in many high-wind areas such as the coast, winload capability of 200km/u is recommended.

Row Spacing:
When designing a PV system that is tilted or ground mounted, determining the appropriate spacing between each row can be troublesome or a down right migraine in the making.  However, it is important to do it right the first time to avoid accidental shading from the modules that are ahead of each row.

Rule of thumb 3.5 times the height for row spacing.

in the American Technical Publishers’ textbook, Photovoltaic Systems. The formula given there for calculating minimum inter-row shading is:

                                                              d = h ÷ tan α

Where, d is the minimum distance between rows; h is the height differential between the top of one row and the bottom of the row to the north; and α is the solar altitude angle.


Data Sheets:
http://www.sflex.com/htdocs/phocadownload/sflex_td_pr_usa.pdf
http://www.nepcindia.co.in/images/NEPC-MMS.pdf