Owners of Australian solar plants are increasingly using tracking technology to squeeze every last watt of energy out of the sun, writes Alan Brown of Array Technologies.
Australia is home to some of the highest electricity prices in the world. Due to a lack of historical transmission and distribution infrastructure maintenance, today’s Australian consumers pay high prices each month to ensure that the country’s electrical grid is both reliable and efficient.
However, despite these increasing costs to maintain the electrical grid, many residents have experienced power blackouts. These factors are causing many residential energy users to adopt more reliable distributed power sources like solar energy.
As a result of this growing consumer demand, Australia is taking broad steps to incorporate renewable energy technologies into its energy mix. Policymakers such as the Australian Renewable Energy Agency and Clean Energy Finance Corporation have made a concerted effort to create a more resilient grid by funding clean energy innovation, projects and technology rollouts.
Solar plays a significant role in Australia’s distributed clean energy transition. A recent report estimates that the country’s solar capacity is on track for 12GW of installed capacity by 2020, double the current total. According to the Clean Energy Council, renewable energy amounted to about 17% of the energy generated in the country in 2016.
While residential solar sites make up a large portion of the country’s current capacity, utilities and independent power producers are starting to develop large-scale installations at a rapid rate. These projects, spanning many square kilometres each, utilize thousands of solar PV modules. Once installed, energy is collected from these sites and transmitted to local grid-connected businesses and homes, providing them with clean, reliable solar power.
Face the sun
While adopting solar energy is an increasingly easy decision, selecting the right technologies to maximize a project’s energy output requires a little more analysis. Module type and brand, inverters and other system components can have significant impacts on the performance of a solar project.
Perhaps the most overlooked and important choice is that of selecting the proper racking equipment. It is important to point out that the racking or tracking equipment is the foundation on which the solar modules are mounted and therefore a very critical component.
Making certain that the racking system will endure what mother nature dishes out over the next 25-30 years without compromising the solar modules or the structural integrity of the system is paramount. In the case of tracking systems, understanding the structural catastrophic risks and the operation and maintenance costs required to keep the system running at peak is equally important.
For the majority of solar sites, installing solar trackers instead of fixed-tilt solutions makes the greatest economic sense. Solar trackers allow the PV modules to follow the sun’s daily path, keeping them perpendicular to the power source, resulting in increased energy production and profitability of the power plant.
Deploying trackers can improve energy output by an average of 20% over similar fixed-tilt arrays. The power gain from tracking and additional expense befits a cost benefit analysis. The additional capex cost to install a tracker plus the operations and maintenance costs over the system life must be less than the value of the extra power it produces to be economic.
Implementing and operating trackers for a utility-scale power plant typically adds about 10% or less to the project cost. In most of Australia, trackers deliver about 20% more power. Spending 10% to get 20% makes a trackers’ economic advantage obvious, but increased power production is not the only benefit of tracking systems.
High in the sky
Fixed-tilt systems capture the maximum energy once a day when the sun moves perpendicular to solar panels, known as solar noon. Trackers, however, rotate the panels to provide optimized power delivery on a continuous basis resulting in a broader, flatter, more useable, grid-friendly power production profile.
Increased energy production from tracking occurs in the mornings and evenings when the sun is lower in the sky. The gain from tracking is also higher in summer months when the sun follows a longer path in the sky. Not only do trackers provide increased energy output overall, but they enable a more efficient use of all system components such as modules, inverters and transmission lines. Trackers typically prove to be more economically viable and optimize the performance of a solar project by providing a lower levelised cost of electricity, which is the measure of the cost of energy levelised over the lifetime of the power plant.
Solar tracking ultimately provides a significant increase in power production that also coincides with the peak power needs of the grid. Operationally, a tracker system’s cost of ownership should be relatively low with high reliability to ensure high uptime and great performance. Operational costs and performance vary by tracker architecture and vendor, so it is important to consider all factors when selecting tracker equipment for a project.
Pros and cons
Solar trackers are becoming more common on solar power plants in Australia. However, the advantages of trackers can be reduced or eclipsed if the equipment risk and O&M costs are not fully understood and monetized over the 25-30-year lifespan of a typical solar project.
Because solar trackers are expected to survive a plethora of meteorological conditions, issues of maintenance and long-term reliability need to be top of mind for solar project developers and owners, especially those building in wind-prone regions. Issues such as “galloping” (a resonance phenomenon that can occur with some tracker architectures) can even be experienced in low wind regions and can have a catastrophic effect.
When selecting a solar tracker, it is important to consider total lifetime costs and ensure that the selected technology is trusted to be safe, efficient and reliable in the project environment. While all trackers are manufactured to accomplish the same goal – track the sun from east to west to maximize productivity and power generation from PV panels – the design, mechanical components and wind load relief approaches can vary greatly. On the O&M front, one of the biggest cost drivers between tracker architectures on the market is the quantity and nature of the electrical and electromechanical components required to operate the system.
A recent report authored by testing and certification company TÜV Rheinland examined the impact of these differences on operation and maintenance costs and overall project economics of two tracker architectures. The report compared two technologies and found Array’s provided 4.6% higher pre-tax net present value and 6.7% lower levelised cost of energy.
Growth in the market for solar trackers is projected to accelerate in 2018. With buy-in from policymakers and utilities, Australia stands poised to increase its leadership in the global solar market with more installations and improving project economics through tracker technology.