Top 10 Factors to Consider for Solar Trackers Feb 16 2016

TOP 10 FACTORST O C O N S I D E R W H E N A D D I N G

TO A UTILITY SCALE PV PROJECT

Photo: Optimum Tracker, Aspres, 5.5MW

S O L A R T R AC K E R S

Contents

Acknowledgements 1Abstract 1About the Authors 1Methodology 3Disclaimer 3About this Paper 4

TOP 10 CRITERIA

#1 Bankability 6#2 Demonstrate Capability via Actual Sites 7#3 Ease of Tracker Installation and Configurability to Site 7#4 Maintenance and Warranty on Parts 8#5 Monitoring and Data Acquisition System 9#6 Structural Strength 10#7 Tracker Specifications: 10

#7a Rotational Angle 10#7b Backtracking 11#7c Power Supply 11#7d DC Capacity 12

#8 Supply Chain 13#9 Local Requirements 13 #10 Performance During Unfavorable Weather 13

(c) The Triana Group, Inc. 2016

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Abstract

The paper discusses in detail the factors to be considered when looking for Horizontal Single Axis (SAT) trackers for a utility scale project. Note that sizable Distributed Generation solar projects (DG) 2MW+ have similar needs regarding tracking system selection.

Every project comes with its own unique requirements and thinking one solution fits all is not the best approach. Here we discuss the top ten criteria to consider before closing on a tracker manufacturer for your utility scale project. Keeping in mind these criteria while evaluating your vendors will help you make a sound decision and ensure that all the important aspects of consideration have been covered.

The authors would like to thank those who contributed to the completion of this study, including companies that have responded to our study and experts who agreed to be interviewed and took the time to respond to our questions; they provided decades of cumulative experience relevant to solar trackers, and their first-hand knowledge helped shape the content of our research.

A special thank you goes out to Madyan De Welle and Wassim Bendeddouche (Optimum Tracker), Rune Hansen (SPG Solar), Heidi Larson (Leidos), Robert Dally (Con Edison Development), Jay Levin (PSEG Solar Source), Christian Malye (Generale du Solaire), and Valerie Blecua-Bodin, among others not mentioned by name, for their valuable contributions.

Acknowledgements

The Triana Group is a New York based company located near Wall Street, which works with international technology companies to introduce their products to new markets. This study was sponsored by Optimum Tracker, a company founded in 2009, with a line of innovative solar trackers for utility scale solar projects. Optimum Tracker contributed expertise but the study was completed independently by The Triana Group.

The study was led by Reed MacMillan, MBA, with a research team including Khushbu Singh, MBA, Crystelle Desnoyer, MIB, and Jabril Bensedrine, Ph.D.

About the Authors


PAGE 2(c) The Triana Group, Inc. 2016

Reed MacMi l lan

Reed MacMillan has been an advisor to the Triana Group since 2013, where she has led market entry and business integration projects for technology companies. Previously, while working for Science Applications International Corporation (SAIC), a Fortune 500 company, she led efforts to win large federal contracts in IT, valued above $200 million. Prior to this, as Training and Operations Manager, she oversaw enterprise training and operations solutions for government agencies, overseeing global teams. During this project, Ms. MacMillan stood up the operations team responsible for the 24×7 availability of multiple worldwide systems. Throughout her career, she has achieved successful business outcomes by connecting people, ideas, and business interests. She holds an MBA from the MIT.

Khushbu Singh

Khushbu Singh is a business development consultant with The Triana Group, Inc. With nearly five years of professional experience in account management, corporate communication, and business consulting, she has effectively managed projects from conception through productive completion across industries. She holds a Masters of Marketing Management degree from Pace University in New York. Her past experience includes positions in marketing and communications at the financial services firm Edelweiss and the global marketing firm Ogilvy & Mather.


Disclaimer

The material presented in this white paper is based on publicly available information. It is provided for informational purposes only. While every effort has been taken to ensure the accuracy of this material, legislation, regulation, and market information are subject to change and may no longer be accurate. The authors assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. This white paper is not intended to provide legal, investment, technical or commercial advice and is for general informational purposes only.

Our methodology relied on interviews with industry experts with experience as solar developers, system integrators, financiers, tracker manufacturers, and select cus-tomers who have used the trackers for utility scale solar projects of various sizes. Additional methods included participation at the leading solar conference, SPI in Anaheim, CA in 2015; review of articles in industry publications available in print and on the Internet documented at the end of this paper; companies’ websites and literature.

Our team reached out to the companies mentioned in this report to give the oppor-tunity to provide feedback on our research, and took responses received into consideration.

Methodology

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About this Paper

To help narrow down this long list to only 10 key criteria, we spent weeks reviewing technical documentation and interviewing experts totaling decades of cumulative experience in the industry.

One of the challenges of evaluating features and functions among single axis trackers is that vendors often highlight features of their product that are distinctive, which can result in suggesting something is more important than another – for example parasitic power consumption (amount of energy used to run the trackers.) Another example of challenge is that regional quality standards bodies have different names although they often are comparable, so evaluators must become fluent in “UL, ASCE, ISO” and the like.

The goal of this list of top-10 factors is to provide a sound basis for single axis tracker evaluation.

The promise of solar energy globally has never been greater, due in part to the reduced costs for solar modules. When combined with the 10-35% productivity gains possible by adding solar trackers to multi-megawatt projects, we think you will be convinced that “if you’re not tracking, you’re slacking.”

Different utility-scale PV projects may need different trackers.

How do you determine which Single Axis Tracker is best suited for your project?


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TOP 10 FACTORS TO CONSIDERWHEN ADDING SOLAR TRACKERS TO

A UTILITY SCALE PV PROJECT

DC CAPACITY

POWER SUPPLY

BACKTRACKING ROTATIONAL ANGLE

WARRANTYAND MAINTENACE

EASE OFINSTALLATION

& CONFIGURABILITY

MONITORING

45o

STRUCTURALSTRENGTH

DEMONSTRATEDCAPABILITY

$

$

$

$

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BANKABILITY


For a solar project to be funded, it must be considered bankable. A project’s equipment and design are evaluated to determine quality according to very specific manufacturing standards and measures.

Those involved in financing, and those who will be running the plant need to trust that their equipment manufacturers will be in business long enough to stand by their warranties.

A bankable tracking system is the one that has passed the financier’s due diligence process and is considered a viable long-term investment. Hence, apart from Lifetime Cost of Energy (LCOE) analysis, project bankability should also be an important factor of consideration. This becomes even more important when multiple vendors are involved in the project. While assessing bankable solutions and providers, project managers should start by reviewing installations and utility scale projects where trackers have already been deployed. A vendor who has multiple projects that have made it through the due diligence process and have been able to establish an operating history are considered to be a safer bet and more bankable. However, while examining operating history, project engineers should not overrate older products compared to valuable R&D-intensive innovations.

Listed below are factors which need to be addressed by technical design specifications to ensure bankability. Also included on this list are some of the major certifications of quality which manufacturers can obtain for their piece of equipment. Note that some of the testing standards are comparable, with the names deriving from the organizational entity testing the product. Therefore, each bankability report may include some of these elements but not all.

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1. Bankability

$

$

$

$

$

$

$

BANKABILITY

Wind tunnel testing

Compliance with UL standards: UL 2703 (Grounding/Bonding Standard for Rack Mounting System) UL 3703 (Standard for Trackers)

ASCE7–10 (American Society of Civil Engi-neers - Minimum Design Loads for Buildings)

Compliance with CE marking

SO Certifications - ISO 9001, ISO 14001, and ISO 18001

Compliance with Eurocodes and SANS

Number of utility scale projects in operation

Technical due diligence on independent engi-neering reports by recognized firms such as: Leidos, Black & Veatch, Garrigues, TUV SUD, to name a few.


“Bankability is by far the most important criteria. Solar growth occurs because of massive capital coming in; capital comes in to finance projects, so people are knowledgeable and intelligent about the technology involved. They have picked favorites with qualified trackers but whichever increases productivity vs costs, will be the new favorite. That transition stage lasts about 5 minutes."

Says a founder of a PV leasing company.

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2. Demonstrate Capability via actualsites

3. Ease of tracker installation andconfigurability to site

Installation plays an important role while considering solar trackers for a large-scale utility project. It is critical to know if the trackers provider delivers and installs them efficiently and effectively, so that the site can be commissioned without issue.

The following players may take part in the installation of a utility-scale project.

Tracker manufacturers – Vendors of solar trackers may manufac-ture or source their trackers from different suppliers. Their forte is designing and manufacturing solar trackers for large-scale utility scale projects.

Installation companies – Separate from tracker manufacturers, these companies are third parties that work closely with or independently from tracker manufacturers and are responsible for installing the trackers. These companies perform leveling work, install foundations, and install the trackers and panels at the project site.

EPC Contractors – They are primarily responsible for the Engineering, Procurement and Construction of the plant. This usually includes selecting the suppliers of solar modules, inverters and other key items of equipment; and finalizing and underwriting the final design and output projections for the plant.

As a construction project manager, you must interact with a number of different vendors and parties. Before selecting a tracker, make sure you understand all the vendors. It is not a norm for tracker manufacturers to execute projects but some of them provide these services. Working with such providers can be a good option as it considerably reduces the chances of error.

DEMONSTRATEDCAPABILITY

When evaluating single-axis tracker vendors, a good place to start is with a review of their prior projects and their sites' operating history. Those are good indicators of their ability to carry out similar projects. Locations of sites also play an important role in determining the capabilities of a particular vendor. Every site comes with its challenges, such as slopes, vegetation, altitude, shape, size, orientation, as well as wind direction and strength; as Valerie Blecua-Bodin points out, "even the nature of the soil could be important", as foundations characteristics are an important factor.

A vendor may have fewer projects than others yet could be more relevant to your specific project. Also keep in mind that vendors with more installed projects may not be the most innovative.

A vendor’s demonstrated capability with sites similar to yours will contribute to your project's bankability and accelerate your understanding of future performance, costs and O&M issues.

EASE OF INSTALLATION & CONFIGURABILITY


"Each tracker technology will differ while being implemented on site (mainly due to the product design). The number of piles needed per tracking row, the flexibility and choice of foundation will impact the overall installation duration and the manpower needed."

Valerie Blecua-Bodin

Another important factor is the foundation work. Building the right foundations for trackers requires calculations and accuracy in execution; most companies provide only the top structure and leave the foundation work to third parties, which can also create a potential for errors. Errors in foundation can lead to movement problems as well as decreased energy output. A poorly built foundation may result in stability issues during high wind conditions. For this reason, signing up with a vendor that provides a complete 360 degree solution is key and is a major consideration when evaluating tracker manufacturers. "Equipment, installation and/or design warranties have to be carefully considered in the evaluation of the tracker's vendor", says Valerie Blecua-Bodin.

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4. Maintenance and warranty onparts

WARRANTYAND MAINTENACE

When developing a PV power plant, it is critical to accurately consider the O&M costs of tracker design. Developing an understanding of maintenance, both preventive and reactive,


"A penny in the tracker or racking costs makes a big difference. Clients will want to make their due diligence in trackers' prices but also in their associated metrics: the installation costs, how easy is the installation process and how long it takes, the related O&M, failure rates of the motors, etc."

Technical Services Manager, PV Field Operator

"You’re installing a 25 year asset so developers want to know how companies back their products."

Says a Business Development expert in solar projects.

that may be required throughout the project's lifetime is important for accurately calculating the cost of the additional energy produced. Your goal here is to maximize system availability, and minimize downtime.

While independent technical assessments are critical for getting projects validated and funded, it is also beneficial to listen to veterans who have been building these projects to learn how they balance trade-offs such as equipment cost, construction costs, productivity, and O&M costs.

Replacement parts should be budgeted upfront as part of system cost. Common tracker systems failures are in motors, gearboxes, and controller electronics. Architectures impact these costs and the types of maintenance that can be expected.

As an example, while it is standard to add a 25% premium to the O&M cost when trackers are used, the main concern for asset managers is to understand how to deal with the product after initial warranties have expired. Since these installations’ lifespan is between 20-30 years, while product warranties are up to 10 years depending on the manufacturer and EPC, there is a gap in coverage.

One of the most expensive parts for trackers is their motor. Numerous types of motors are available, such as: Stepper motors, Permanent magnet brush dc motors (PMDC) or Brushless dc (BLDC) motors. Brushless dc motors are the most efficient today; they are maintenance-free and have a low cost of operation. These motors do not have wear-prone brushes, are highly efficient (typically 85 to 90%) and have a distinct advantage when a short stowing time is important.

Energy consumption by motors is often something that solar tracker manufacturers stress to differentiate themselves from their competitors. As mentioned earlier, this “parasitic consumption” as it is generally called, should not be a major factor in tracker selection. Project managers of large-scale utility projects do not consider this to be a deciding factor when evaluating a project.

When developing a PV power plant, it is critical to accurately consider the O&M costs of tracker design. Developing an understanding of mainte-nance, both preventive and reactive, that

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5. Monitoring and Data AcquisitionSystem

MONITORING

Utility-scale PV plants that require high performance, low downtime and rapid fault detection need a data monitoring and supervisory control and data acquisition (SCADA) system. These systems provide control and status indication for equipment included in the substation and across their solar plant, which also enables them to “track” the trackers’ performance. This control system may be combined with a data acquisition system that gathers remote equipment status for display or recording.

Solar trackers generally come with their own sensors, including but not limited to inclinometers. Some vendors offer systems that enable controlling solar trackers with an embedded positioning algorithm, field communications support, and a variety of specialty inputs for inclinometers and position feedback sensors. Most of these systems support MODBUS, DNP3, and other industrial protocols, and should allow for easy interfacing with full-scale SCADA packages for grid dispatch and control.

Monitoring and comparison also help raise warnings on a daily basis if there is a shortfall. Faults can be detected and rectified before they have an appreciable effect on production.


may be required throughout the lifetime of the project is important for accurately calculating the cost of the additional energy produced. The goal is to maximize system availability, and minimize downtime.

While independent technical assessments are critical for getting projects validated and funded, it is also beneficial to listen to veterans who have been building these projects to learn how they balance the trade-offs such as equipment cost, construction costs, productivity, and O&M costs.

Replacement parts should be budgeted upfront as part of the system cost. Common tracker systems failures are in motors, gearboxes, and controller electronics. The architectures have an impact on these costs and the types of maintenance that can be expected.

As an example, while it is standard to add a 25% premium to the O&M cost when trackers are used, the main concern for the asset manager is to understand how to deal with the product after initial warranties have expired. Since these installations’ lifespan is between 20-30 years, while product warranties are up to 10 years depending on the manufacturer and EPC, there is a gap in coverage.

One of the most expensive parts for trackers is their motor. There are numerous types of motors available in the market such as: Stepper motors, Permanent magnet brush dc motors (PMDC) or Brushless dc (BLDC) motors. The most efficient today are brushless dc motors, which are maintenance-free and have a low cost of operation. These motors do not have wear prone brushes, are highly efficient (typically 85 to 90%) and have a distinct advantage when a short stowing time is important.

A high level of technical expertise is needed to detect certain partial faults at the string level. Otherwise, it could take many months for reduced yield figures to be identified. Lower yields may lead to appreciable revenue loss for a utility-scale PV power plant.

The key to a reliable monitoring and fault detection methodology is to have good knowledge of solar irradiance, environmental conditions and plant power output simultaneously. This allows faults to be distinguished from, for example, passing clouds or low resource days.

Three main methods provide data on solar irradiance and weather conditions: on-site weather stations (which is typical once the site is in operation), meteorological data gathered from a weather satellite, or from local weather stations. There are pros and cons for each method, and some experts focus more on the Performance Ratio, which is used to compare PV systems independent of size and solar resource. By detecting a drop in the performance curve, they can quickly notice anomalies in production.

The rotational angle of trackers plays an important role by positioning them to capture maximum solar energy. This is especially important in a utility scale project, and can help developers achieve greater utilization of their site and help to generate more revenue.

The optimum angle depends on a number of factors such as location, distance from the equator, site topography, plant foundation, distance between panels, and the earth’s movement around the sun during different seasons. In other words, there is no one-size-fits-all.

The rule of thumb is to install panels in a manner that make sunrays reach them at a perpendicular angle, ensuring that the angle of incidence should be 0 degrees or as close to 0 as possible. Algorithms are used to calculate the solar azimuth and zenith angles; these angles are then used to position solar panels to point towards the sun. Some algorithms are mathematically based with astronomical reference points, while the others use real time light intensity readings and adjust accordingly. Trackers typically offer rotational angles ranging from +- 45 to +- 60 degrees. Higher angles may not necessarily provide significantly better results: you must configure your installation in accordance with your specific site characteristics.

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6. Structural Strength

STRUCTURALSTRENGTH

Since solar trackers have moving parts versus fixed tilt solutions, the installation's structural strength and durability must guarantee that trackers will function well over the project lifetime.

Warranties are generally shorter for trackers than for fixed tilt structures. A solar tracker makes one revolution per day, which totals 7,300 revolutions in a 20-year period. In an environment with calm and stable weather this movement is not significant in terms of wear and tear that compromises the installation. Today, nearly all environments are faced with weather challenges, and so it is critical to have an understanding of the forces that may impact the structure such as wind speed, snow load, rain storms, sand and sun, especially in desert areas, where the durability and structural strength of the trackers are especially important.

Systems in close proximity to salt water require more weathering, steel parts need additional galvanization during welding, and gears and exposed parts may require protective boots. Generally, installing trackers is not recommended in areas prone to hurricanes or heavy snowfall. However, most vendors can augment the strength of their designs and provide greater wind speed tolerance. Without considering anomalous weather events, studying data from prior years should provide a fairly accurate picture of wind speeds in a specific region. In some specific locations, gusts and wind direction are also important.

7. Tracker Specifications

ROTATIONAL ANGLE

45o


a. Rotational Angle

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b. Backtracking

Solar trackers vary significantly in how they handle their own needs for energy, which is generally referred to as parasitic power load. Vendors seek to decrease energy consumption required to move trackers, since it counts against the gains generated from adding trackers.

There are active and passive tracking systems. Passive tracking systems use the shifting weight of a liquid refrigerant to keep the array of modules pointed at the sun. Active tracking systems use a controller and one or more actuators for targeting. Active tracking is more accurate — but more expensive — than passive tracking and also requires a power source for the controller and various actuators.

“It is a mistake to get too concerned about tracker engines' energy consumption” says Christian Malye, a Chief Technical Officer overseeing several utility-scale PV projects. The engine works about 5 seconds every 3 to 4 minutes, resulting in a loss of energy that is far less than that of the transformers. He also mentioned that in comparison to the energy cost for air conditioning operations buildings near the site, the “parasitic load is negligible.”

c. Power Supply

BACKTRACKING

Solar trackers can be made more efficient by the use of backtracking. Backtracking refers to solar trackers’ ability to move and adjust according the sun’s position. All trackers must be able to adjust simultaneously to avoid any shading on the adjacent tracking row. Shade on solar panels reduces the electric output and compromises the overall efficiency.

A backtracking algorithm takes into account the sun's position, spacing between tracking rows, and the size and shape of panels in the rows. Its goal is to minimize shading and maximize perpendicularity of sun’s rays on panels to harvest the maximum amount of solar energy.

Other factors that impact output are topography, location, season and weather. Because of these diverse site-specific factors, customized backtracking solutions are needed. This might mean that each array is treated differently, requiring a tailored algorithm adjusted to ensure the maximum solar energy can be harvested. Each tracking system technology has its specific backtracking solution and associated software.

POWER SUPPLY


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A photovoltaic array consists of multiple photovoltaic modules that convert solar radiation (sunlight) into usable direct current (DC) electricity. A grid-connected system, such as a PV plant with solar trackers, is typically connected to and feeds energy to the public electricity grid. Feeding electricity into the grid requires the transformation of DC into AC by a special, synchronizing grid-tie inverter. Most modules (60 or 72 crystalline silicon cells) generate 160 W to 325 W at 36 volts. Currently most utility-scale project are based on 305-315 Wdc modules (modules in 60 cells are not often used on trackers.) The DC power supply must have components that can handle tracker specifications for the linear actuator and slewing drive.

PV systems may be built in various configurations, two of which are related to utility-scale projects:

Other configurations (such as off-grid with or without battery, for DC-only or both AC and DC) exist but are related to stand alone systems which won't use trackers.

The number of modules in a system determines the total DC watts that can be generated by the solar array. The inverter controls the amount of AC watts that can be distributed for consumption. For

d. DC Capacity

DC CAPACITY

Appliances Grid-tie without battery

Grid-tie with battery storage (rare in the US)


example, in a large scale project, the standard in the industry is to use 2,000 kWac inverters pad, and the usual DC-AC ratio is 1.25-1.45 depending on the location.

When calculating the LCOE for the PV project, it is important to ensure that the inverters are sized appropriately to capture the additional energy generated by your trackers.


8. Supply Chain

Solar project management is complex, and selecting the right supply chain partner is as important as executing project construction. Large solar projects have numerous requirements that need to be fulfilled by a variety of manufacturers and suppliers. Selecting the right suppliers is vital for project success and helps avoid costly overruns and delays.

Project managers make sure to meet with suppliers, EPCs and developers to discuss their project details. Discussions about components' manufacturing timeline, shipping and delivery schedule, and on-sight assembly can go a long way and provide important insights into project execution capabilities of solar service providers. This helps you mitigate the risks that come with large scale projects, and increases chances of project success at every step of execution.

9. Local Requirements

Each country and state has its own specific requirements, which may range from standards to labor regulations. Few tracker manufacturers -if any- can provide systems and installation that meet the requirements of every single location without any compromise in effectiveness or quality. Local specificity significantly affects which solar tracker to chose. Once again, there is no one-size-fits-all.

10. Performance duringunfavorable weatherOne of the most critical but not very often discussed issue is the amount of energy generation contributed by the trackers during cloudy days. All 12 months of the year are not the same and the amount of sunlight that reaches the earth considerably depends on how clear the sky is. When solar tracker manufacturers claim that installing trackers can improve the energy production by up to 30%, it means this is the case under perfect weather conditions. There is little that is discussed about cloudy days when sun rays don't reach the surface as strongly. It is important that project managers discuss such scenarios and take them into consideration before deciding on which manufacturer to choose.

Some manufacturers, such as Optimum Tracker for example, have patented technology to collect significantly more energy than older trackers even on cloudy days.

"Logistic is also a key factor. It should be encompassed in the procurement ability of the vendors. The EPC will dispatch the product on site, but the tracker's vendor will be responsible to properly and efficiently deliver the equipment on site."

Valerie Blecua-Bodin


For further information:

[email protected]

1-646-417-8136

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Top 10 Factors to Consider for Solar Trackers Feb 16 2016