Directional wind effects on single-axis solar tracker stow strategies explored in new whitepaper

Ideematec solar tracker

As we enter the next decade of the utility-scale solar PV rollout, there are many uncertainties surrounding the future of the industry. Uncertainty surrounding the “greenness” of coronavirus recovery plans, and further legislation to disincentivize the use of fossil fuels puts a massive question mark beside any estimate on future capacity additions.

Uncertainty around numbers aside, one thing is for certain; the solar industry continues to see impressive growth in all corners of the world. While that statement itself points to a positive trend – it brings with it an issue that has been slowly rearing its head as solar PV finds its way to more and more regions:

How can solar PV installations thrive in sub optimal conditions?

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It makes sense that the first generation of utility scale solar was highly concentrated in what could be considered as ideal locations. High solar irradiation, predictable wind conditions and relatively low labor costs characterized many of the early regions to see high solar PV penetration. As module costs continue to fall year over year, and a global push towards more sustainable generation technologies continues, utility scale solar is finding its way to more non-traditional markets.

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This brings with it several new factors to take into account when planning a system. First off, solar installations in less sunny regions benefit greatly from a solar tracker that can help maximize the time panels are facing the sun. A new study from the Solar Energy Research Institute of Singapore, and published in Joule, suggests that 93.1% of the worlds land area can achieve the lowest LCOE by using single axis trackers equipped with bifacial PV panels. This makes understanding the physical limits of any tracker system vital to the long term security of any utility scale PV plant.

In regions with higher than average wind conditions, especially those where wind direction is likely to change, ensuring your system can stand up to the elements will be one of the keys to long lasting performance. It is no longer enough to build systems designed for ideal conditions – the shift to a society powered by renewable energy will necessitate a rethinking around how we plan and build utility scale PV plants. Increasingly erratic weather patterns caused by climate change will also lead to investors and developers opting for the most secure options available in order to ensure long term bankability.

The role of trackers in protecting system health

German tracker company Ideematec, a manufacture single-axis tracker systems, has commissioned a new white paper examining how investors and developers can better ensure the safety and efficiency of their installations in high wind events. To be more specific, the white paper attempts to shed new light on the issue of changes in “wind directionality”– a topic often overlooked when looking at solar tracker security and energy yields.

The new white paper takes a look at data from Ciara, an extratropical cyclone which made its way across Europe this past February. The wind data from the storm shows that considerable changes in wind direction are not only possible, but common throughout the course of a storm. The data, taken from the German Meteorological Service, shows changes in wind direction of up to 40° in 10 minute intervals, and 30° at speeds above 20 m/s, a speed at which many tracker systems enter stow position.

The whitepaper explains that over the past several years, the vast majority of utility scale PV failures have occurred due to adverse wind or weather conditions. This makes fully understanding the threat posed by high wind events particularly important to investors and product developers alike. Understanding these high wind events, however, is only half the battle.

Typically, stow strategies can fall into two distinct categories, 30° stow, and 0° stow. Systems that opt for a 30° stow face the challenge that they are only designed for wind approaching from one 180° wind sector – any substantial change in wind direction could lead to substantially higher wind loading, putting the system at risk of failure.

The importance of this knowledge will only compound as the global rollout of utility scale PV continues. As solar PV continues to expand into more and more regions, with vastly different climactic conditions, understanding how single-axis solar trackers protect panels as well as the overall system is key to ensuring a long service life.

As we enter a new era of utility scale solar PV, one where plants are being built in more locations around the world, the importance of securing systems against the elements will only grow. Ensuring the long term bankability of PV systems is vital to ushering in the post-fossil fuel energy system that is needed to avoid the most serious effects of climate change. The winds of change are most certainly blowing in the utility scale PV sector – how confident are you that your system will hold up to the changes of wind?

Read the full white paper from Ideematec here.

Travis Hendrix is in public relations for DWR eco GmbH

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