Five keys to Northeast solar tracker projects

Publish Time:2022-06-14 Sources:
As the utility-scale solar industry has grown from 1 GW to 50 GWs over the past decade, smaller Northeast states face dwindling land prospects and the challenge of developing highly difficult terrain for new solar projects. Northeast states also face increasingly extreme weather, as there were twice as many extreme regional snowstorms in the U.S. between 1961 and 2010 compared to 1900 to 1960. It is therefore more essential than ever that EPCs ensure solar systems can withstand higher wind speeds and snow loads.
At the same time, utility-scale solar projects are increasingly utilizing solar trackers, as opposed to fixed tilt systems, in order to maximize energy yield and project returns. In fact, roughly 70 percent of new utility-scale solar projects in the US now come with trackers, but large-scale projects with single-axis trackers are historically less common in the Northeast U.S. This is due in part to the fact that site complexity and cold weather conditions in these regions pose greater development challenges for solar tracker projects in particular.

1. Closely assess topography to determine tracker design, row break locations and various post lengths needed.
There is not a lot of flat land or areas with consistent slopes remaining in the Northeast, as many parcels of land have significant changes in grade, swales, drainage ditches and low laying areas. These changes in elevation need to be taken into account when designing trackers to minimize project costs and maximize energy production. Row breaks need to be utilized at peaks or valleys in the grade to help save costs on site grading or additional material. When this is not possible, you need to take these elevation changes into account when ordering post lengths.

2. Conduct extensive geotechnical investigation prior to choosing a racking manufacturer to achieve proper tolerances in light of subsurface refusals.
Tolerances on trackers are much tighter as compared to fixed tilt systems. When refusals such as bedrock, cobbles or boulders are encountered, it is more difficult to achieve the tolerances for foundation installation. When posts hit a cobble or obstruction below grade, it can easily move the post out of tolerance. Therefore, extensive geotechnical investigation must take place prior to selecting a racking manufacturer to ensure that proper tolerances can be achieved and to determine allowable remediation efforts when an obstruction is encountered.

3. Hit the design depth for the drive post without a pull test to avoid any subsurface refusal issues.
When subsurface refusals are encountered in the context of fixed tilt systems, so long as the minimum depth is achieved, you can simply perform a pull and lateral test on the post and then cut and punch new holes. However, when it comes to trackers, the minimum embedment is typically much deeper for a post installation as compared to a fixed tilt system. For the center, or drive post, you must achieve the design depth or have an engineered solution (i.e., concrete foundation) to install.

4. Proactively manage ponding water and limit machinery use to ensure proper site access and prevent muddy, difficult to navigate sites.
Many of the properties where solar trackers are installed are in fields previously used for agricultural purposes. These fields might look ideal at the outset, but they are easily affected by the weather and can quickly turn into muddy fields. In these scenarios, equipment machinery, and the type of equipment used, must be limited when working in the fields. It is also important to keep positive drainage on the site so that there is no ponding water, or the unwanted pooling of water. Site restoration, temporary or permanent, is important to stay in compliance and to help control water.

5. Properly stage material parts, particularly during the winter season.
Winters in the Northeast can start as early as October and run as late as March. Snow, ice, sleet, and freezing winds make it difficult to install intricate pieces of tracker systems. Properly staging material parts is critical, as parts left in the array can be easily lost when it snows.

These five keys to designing and constructing utility-scale solar tracker projects in the Northeast U.S. minimize project risks and installation times, as well as maximize project returns.