Solar Mounting Structures: Racking Matters

Tripura Chalks Out 'Tripura Energy Vision 2030 Roadmap'

Globally, solar installations have been growing at an impressive pace. A large share of growth has been contributed from India, and with 100GW of target by 2022 in its hand, India is on the verge of becoming the world’s biggest solar nation. Continuous reduction in the solar system prices with respect to higher grid rates is resulting in increasing global demand for solar solutions and thus leading to its rapid growth. Solar is undeniable the future and a leading source of renewable energy. Solar panels work best when they receive shade free sunlight for maximum number of hours, mounted at precise tilt angle with face directed towards the south. This is where Solar Panel Mounting Structures comes into the picture. One of the largest areas of innovation within solar panel installation involves the mounting system.

Module Mounting Structures play a vital role in efficient working of a solar power system, both in utility and rooftop. While most of the components of balance of system (BOS) such as inverter, DC cables, junction boxes, transformers, etc. are readily bought from the equipment suppliers, the workmanship of an EPC contractor is reflected mainly through module mounting structures and wiring management.

These structures help panels to rest com-fortably, prevent from being damaged and more importantly position them at precise tilt angle to harness maximum sun’s energy. Mounting structures can be made for rooftops, ground mounting, carports and sun tracker solutions which now have seen a lot of developments in terms of weight, material, adaptability and ease of installation. There have been many technological innovations that have led to reduced cost, faster and better installation, high durability and with enhanced output.

Recent installation of solar project in India has adopted various Solar Mounting Tech-nologies and design which include the structures made of galvanized iron as well as aluminum structures. Some of the projects have adopted a combination of steel structure and aluminum structure where in vertical legs are made off hot dipped galvanized steel and rest of the members are made off extruded aluminum structure. Typically module mount structure comprises of following components.

Moreover, falling cost for module mounting structures has been one of the biggest contributor to the fall in project cost. They have fallen by almost 60% in the past 4-5 years. The manufacturing of structures is a fairly consolidated market with the top five companies in India controlling 80% of the market share. These players have a cumulative capacity of 2,300 MW per year. This might seem like a solid base for future growth. However, the demand in India is cyclical and driven by policies. Timely deliveries for the entire 2,300 MW will already be an issue, leave alone catering to a 4,000-5,000 MW market. The costs for mounting structures can also go up if there is a spike in capacity addition. However, this increase will be short lived as companies can start buying parts of the structure from other steel fabricators.

Any solar system is designed to function for 20 to 25 years thus material plays an important role in the overall solution. The strength of the material is defined by the geography and environment of the location being installed. Hence, there is a growing need for highly durable, rust-free, corrosion-resistant materials in the industry. This is leading to the emergence of evolutionary products like rust-resistant steel that have become highly popular in the solar panel market with its competitive pricing and greater durability. There are several types of steel depending on its weight, strength grade and coating which involves different prices. While selecting the material one should look at the warranty provided by the company for maximum return on investment. Probably, the most competitive solar product market, mounting systems are an important element of solar arrays—they secure solar panels to the roof or the ground. Here, we go over the basic categories of roof-mounted solar systems to help new installers get a grasp on installation.

Types of Solar Mounting Structures

The correct and proper choice of the Mou-nting Structures for solar system projects is very essential in terms of the overall production, efficiency and lifetime of the solar panels. Since it is a costly investment, the choice of mounting systems should not be disregarded as a minor consideration. Solar modules need to be secured, mounted and tightened on a very stable and durable structure, protecting the array against imp-acts from wind, hail, rain, snow and even minor earthquakes. They are either mounted on ground, on roofs or on poles. There are five basic types of mounting structures of which four are fixed-angle types and one variable-angle type:

1. Roof Mounted Racks
2. Ground Mounted Racks
3. Top-of-pole Mounted Racks
4. Side-of-pole Mounted Racks
5. 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. These also consist of design engineering considerations which include seismic behavior analysis, boundary layer wind tunnel testing, and UL 2703 certification for grounding and bonding. Roof mounts are optimal when your home or building has sufficient space for all of the solar panels that you require. They also have the option of being fixed or adjustable and can also be installed with a solar tracker.

Ground Mounts, as you might guess, are primarily used for mounting solar panels on the ground anywhere on your property. If your roof lacks the space for a roof mount or is heavily shaded by trees or location in the sun’s path, this is a viable alternative. These are usually adjustable to allow them to tilt up or down for maximum solar abs-orption at various times throughout the day. . The disadvantage is that 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).

Pole Mounts are used for anchoring solar panels to, you guessed it, poles. There are two major kinds of pole mounts, “top-of-pole” and “side-of-pole”. The former allows the solar panel to sit on top of a pole, elevated several feet off the ground. The latter anchors solar panels to the side of poles. 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 is 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. Solar trackers are an automated system that allows your panels to track the sun’s path throughout the day for optimal solar exposure and collection. However, while solar trackers do increase efficiency and reduce manual upkeep of your panels, they are not commonly used due to the hefty increase in total cost and the addition of another moving part that potentially break down and cause problems for the array.

Different Types of Roof Mounts

Flush Mounts are the first type of roof mount that we will cover. They are an inexpensive and a simple option suitable for most roof-mounted solar panel installations. They are generally not adjustable, and as the name suggests, they are designed to lay flush with the roof surface on which they are mounted. The solar panels are generally secured using metal clips that hold the panel in place, leaving about 2-4 inches of space between the roof and bottom of the panel. This allows for plenty of airflow along the underside of the panel, which keeps the panel cool and operating at maximum efficiency. If a panel overheats, its efficiency drops and so does its life. These mounts are great for homeowners, less so for business owners. Roof mounts in general aim to protect your roof as well as the solar panel itself. The flush mount reduces wind load on the solar panels. Flush mounts are ideal for reducing the dead load on your roof, they work for any type of system, are suitable for high wind areas, there is room for flexibility in the panel slope and orientation and they provide minimal interference with roof drains.

They are not without faults though. Depen-ding on the type of roof you have, installing a flush mount could require a roof penetration (penetrations are not required normally), which will increase the risk of roof leakage.

Ballasted Mounts are similar to flush mounts, but use weights to hold the solar panels in place on your roof. This design can save labor time and costs, but presents an additional challenge of getting the weights onto the roof, which can be quite substantial when dealing with larger systems. Ballasted mounts do not require roof penetrations, are faster and cheaper to install and allow for a panel tilt of up to 20 degrees for optimal solar exposure. However, this mount increases the load on your roof, has lower power density, and is less suitable for high-wind areas. They are limited by certain site conditions like roof slope and building height.

There are also Hybrid Mounts, which you can probably guess are a combination of flush mounts and ballasted mounts. They use some structural elements of both mounts to accommodate some roofs that can’t support either. Hybrid mounts require minimal roof penetration, can be fast to install (depending on the model) and allows for custom design optimization based on factors like load bearing and wind. These mounts are typically more expensive and can take up more space on your roof, leaving less room for your system.

Roof-ground Mounts are similar in design to normal ground mounts, but are able to “sit” on your roof. Depending on the type of roof you have, this may be better than a flush mount. Roof-ground mounts have the ability to come adjustable or fixed for maximum solar exposure throughout the year.

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.

Structural integrity is of paramount impo-rtance. Just like any other component of a building, solar systems must be structurally sound and secure. Numerous problems can result if systems are of low quality or poorly installed. The solar industry is committed to bring remarkable products and systems to the Indian and global markets to enhance solar development across the world. The entry of innovative technologies and products in the sector is paving the way for a cleaner and greener future.