Reliability is one of the single most important factors when designing a solar tracker. The final product has to withstand being exposed to the environment for as long as 20 years and is often subject to especially harsh conditions with temperatures fluctuating from -40 to +40 degrees Celsius. Just one failed drive unit will greatly reduce the electricity output, depending on the time of day and position the drive unit was in when it failed. This is due to having one single drive unit per axis moving a whole table of solar panel arrays. Every second of the array being misaligned decreases power output and increases the LCOE.
In the following, we will explore just how exactly we can ensure that the drive units will still be functioning flawlessly after more than 20 years of being exposed to adverse conditions.
When choosing the right solar actuator for the solar tracker, there are a few characteristics that point towards higher reliability. The gears, screw, limit switches and nut used should be rated for significantly higher endurance than the maximum rated force of the electric solar actuator. The nut should be made from a polymer material instead of from metal, as this provides self-lubricating abilities ensuring the unit remains maintenance free. The screw on the other hand should be a metal one.
As the actuator will be operating in all weather environments, the IP rating is another important factor. While mounting it in a downward position can reduce the probability of moisture penetrating the housing, it can in no way ensure zero ingress. We recommend choosing a model that is rated at least IP66. As the solar tracker actuator will be retracting and extending while exposed to water, it is imperative that the IP66 rating applies to both static and dynamic operation to prevent moisture being pulled inside the housing while retracting when wet.
Another factor to consider is the testing process the manufacturer has used to determine the lifetime of the actuator. No one is able to test a unit over the fully expected lifespan as this would take 20+ years and the product would already be redundant by the time testing is completed. Instead, manufacturers test how many times the unit is able to retract and extend before it starts exhibiting issues. The resulting number is then divided by the average daily amount of cycles the actuator would be performing in a typical application.
Differences are apparent when looking into other testing methods, such as IP testing and electrical and mechanical tests. Not all manufacturers employ the same testing methods. The extent of the testing also varies. While some companies will test freezing resistance to -20 degrees Celsius, others will test to -40 degrees and beyond. Based on the location of the tracker this may have a significant impact on expected lifetime and operational uptime – if the internal lubricant freezes, the actuator will stall – at best until it is thawed.
Most manufacturers offer warranties on their drive units. These, however rarely cover for more than 5 years after installation, leaving a financial risk for the following 20 years of solar panel lifetime. That is why warranty coverage shouldn’t be a main factor when making the purchase decision for such a unit. Instead, focussing on mechanical soundness and the best fit value proposition for each individual application is the way to go.
In conclusion, choosing the right solar tracker linear actuator is one of the biggest challenges in designing a solar tracker for long term reliability. The best way to find the right fit is by testing different units, configurations and modifications until the necessary lifetime and reliability level has been reached.
To give you an idea how serious we take reliability, here is a quick overview of how Progressive Automations ensures long term reliability for your tracker:
- Rigorous Testing: Before any new product is released, it undergoes a rigorous and highly comprehensive testing process to make sure it doesn’t just meet but exceeds expectations. We intentionally break a large number of units during this process to fully understand their limits.
- A decade of experience: More than 10 years of Progressive Automations means little still surprises us. If you are experiencing issues with your actuator, chances are that our engineers will know how to fix it right away and have worked on a similar problem before.
- Tailored Sampling Process: Our sampling process has been built to be highly tailored to your needs. We will not rest until you are 100% happy with the final product and all desired customisations have been implemented as specified.
- On-site Implementation Support: We will deploy dedicated engineers to your site and help you oversee installation and implementation of our components. This ensures that the installers don’t mishandle the product and make resolving any installation issues easy.
- High Quality Products: Our solar electric actuators carry the CE certification and have further been certified for UV-Ray exposure, salt exposure and Ingress Protection.