This case study highlights details regarding single and dual axis solar tracking systems and also reasons as to why we fail address the key errors of temperature fluctuations related to solar trackers. This case study also focuses on some crucial cases faced by Dunkermotoren, a German subsidiary of the American group Ametek in the division of Advanced Motion Solutions as they experimented several venting options to eradicate potential seal failure due to pressure differentials. Lately, the company displayed the result of defining a GORE® Metal Vent to equalize pressure within the motor by maintaining sufficient air flow and moisture vapor to pass in and out of the enclosure freely.

Keeping an understanding about solar tracker, one needs to have an absolute knowledge about how solar power operates. Solar power generates the energy stored from the sunlight. The solar power systems consists of multiple components such as inverters, batteries, PV cells, and panel holding equipment among others. However, with the establishment of utility-scale commercial solar plants, to ensure high efficiency and energy output there was a requirement of solar systems which are able to collect solar energy throughout the day. Hence, the solar trackers were introduced. Since then, Solar Trackers are widely used to keep solar panel oriented directly towards the sun as it moves through the sky.

Solar trackers are systems that help in positioning an object at an angle absolute to the sun. A solar tracker is commonly used to position a solar panel which is perpendicular to the sun’s ray at the same time, and place telescopes so that they can determine the direction of sun in a correct manner. The solar trackers adjust the direction of the solar panels according to the movement of the sun. When the panel is positioned perpendicular to the sun, it can achieve more sunlight striking on the panel and maximum energy is absorbed which is subsequently converted into power.

Tracking systems

The solar photovoltaic systems hold a functionality of turning and facing the sun throughout the day using single- or dual- axis solar tracking systems. All solar power plants employ smart tracking systems, whether they are photovoltaic, concentrated solar systems, or concentrated photovoltaic system. These existing systems fully rely on sensitive electronic components: integrated electronics to regularly determine whether the angle of incidence of the sunlight is correct. The service life of these tracking systems can be for a long time- typically 20 to 25 years. Solar power plants can be installed in specific locations that experience critical climate conditions such as wide temperature ranges, dust, hail, high winds, driving rain, and long hours of direct sunlight.

The electronic and motor system can be protected in various ways, yet many of them fail to address the key errors of temperature fluctuations: pressure differentials. Exposure to direct sunlight in the daytime and cold air at night causes significant temperature changes outside the housing. A sudden rain storm in hot sunny day can cause the outside temperature to drop rapidly. Such sudden changes can cause essential pressure differentials inside the house. However, producing a vacuum that puts stress on the housing seals. Over time, this fatigue can lead to failure – creating leak paths for liquid and particulate contaminants.

Partial solutions to the problem

The measurements referred to shield the electronics in solar tracking systems suffer from certain drawbacks, they are operating with the leading partial solutions. For illustrations, desiccants can be placed inside the housing, but they will catch the relative humidity within the enclosure. Moreover, it cannot come as a positive result as they do nothing to balance the pressure differentials. Also, as they require replacement at regular intervals, these desiccants incur maintenance costs.

Another approach is mainly concerned with potting the electronics. While potting summarizes them and provides a protection from contaminants, it also subjects them to the stresses that arise from the different thermal expansion coefficients of the potting, housing and PCB material. Moreover, it also demands for labor-intensive chemical processes.

Instead of allowing air to flow smoothly in and out of the house, vacuum formation can be refrained by not hermetically sealing the enclosure. The housing might fail to attain the higher ingress protection ratings that is required by the solar tracking systems, as the problem is with the tortuous path which cannot hold water and contaminants from entering.

Venting is the answer

One approach provides a comprehensive solution and avoids the drawbacks of other protective measures: venting. Vents rapidly and continuously equalize pressure differentials while effectively reducing condensation. At the same time, vents effectively block the ingress of dust, dirt and water to sustain enclosure integrity and maintain high IP ratings over the lifetime of the housing.

Dunkermotoren is a global manufacturing company with operations in United States, China, and Germany, provides solar tracking motion solutions that are installed across the globe. The company successfully engineered a sealed housing with O-rings and connectors seals to provide a protection to its motor components from liquid and contaminant ingress; however the installations in field were coming up with motor corrosion issues. These issues increased customer returns and warranty claims. Moreover, Dunkermotoren is focused on improving the motor’s durability to meet the intended service life and increase customer satisfaction.

GORE® Protective Vents

Dunkermotoren’s engineering team decided to test several venting options to eradicate potential seal failure due to pressure differentials. Based on the customer feedback, the engineering team decided to evaluate GORE® Protective Vents.

Analyzing the results of these tests and the requirement to combine the vent into an existing product design, Gore recommended a GORE® Metal Vent. This vent defines a functionality to equalize pressure within the motor by maintaining sufficient air flow and moisture vapor to pass in and out of the enclosure in a free behavior. At the same time, the vent also serves as a barrier to provide a maximum IP rating against dirt, salt, dust, liquid, and other contaminants. The rugged screw- in construction of GORE® Metal Vents extends the service life of solar tracking systems and also made it stress-free to integrate into new or existing product design.

According to Will Vinson, President of Dunkermotoren USA, Inc., their goal was to develop a more durable product to exceed service-life expectations. “With our new STM™ product, we wanted to deliver a tracking system that would last for the expected life of the solar energy system – more than 20 years. GORE® Protective Vents extended the life of our motors by achieving the durability of IP67 protection against exposure to harsh environments. Gore’s engineers understood our requirements and worked like part of our team to ensure that our products deliver the performance our customers expect.”