A blog series chronicling all the solar array creation action
As we shared in our last South Carolina construction update, building a new solar array is one of the most challenging aspects of maintaining a successful community solar program. So, we want to shed some light (see what we did there?) on how solar array construction works – and let you know where we are in the process with our three new solar arrays in the Palmetto State: Springfield, Nimitz, and Curie.
Initial Construction Activity
After the sites were cleared of bushes, tall grasses, and shrubs, commercial teams began surveying. Surveying includes many aspects of the overall site plan, including access roads, fences, equipment locations, piles, and more. Once the survey team completes their work, the engineers can then plan structures accurately and safely.
Pictured: Teams use surveying equipment to plot out where each pile will be drilled.
In the next stage of construction, storm water management materials such as plastic silt fences, filter socks, or check dams are placed throughout the site to minimize site erosion that can occur when there is a lack of vegetation.
Pictured: A filter sock is placed on-site to minimize water and debris runoff.
Permanent fencing and access roads are then installed, allowing the piles to be placed. The amount of piles needed depends on the site’s size. Springfield, for example, is an 8 mwdc site and requires 4,900 piles. Once the piles are in place, the racking (casing for the panels) and the panels themselves are carefully installed.
Fun Construction Facts
• At peak construction at Nimitz, crews were installing as many as 6,000 panels per day
• The panel modules we use are frameless, which helps mitigate pollen and dust buildup
• Each panel can withstand wind speeds over 100 mph
• There are up to 216 individual solar cells within each solar panel
To date, the panels are almost completely installed at our Springfield site, and we’ve deployed our Springfield construction crew to the other two sites, Nimitz and Curie.
Pictured: The last boxes of panels at Nimitz being staged in the array field for installation.
Coming Up: Inspections and Approval
As array construction at all three locations draws near, we can now focus on the inspection and approval process. Local authorities need to check each site to ensure they arrays were built and installed to the approved plans. Everything from the size of the wires to the spacing between inverter equipment is scrutinized for safety, which is our number one concern. Once our building permit is stamped with the coveted “final inspection” seal of approval, we can then schedule what’s called a “witness test” with our partner utility – in this case SCE&G.
Pictured: Looking inside a combiner box at Springfield. The combiner box aggregates a row of panels, and sends the power to the inverter.
The first part of the witness test verifies the arrays match the utility approved design. First, like the local building department inspection, the utility representatives confirm the array was designed and installed to all previously approved specifications. If this is passes, the system is energized and a dedicated CEC team can begin the functional testing phase. Here, inverters are turned on, one at a time, to monitor system levels, troubleshoot any issues, and make sure everything is functioning properly.
Once everything is running, the utility returns to the site for the second stage of the witness test. Here they randomly select an inverter to test for automatic power shutoff if the grid loses power. This simulation serves a crucial safety function – ensuring there would be no electrocution risk if that particular inverter required repair work at some point in the future. A “phase test” is also conducted where power is shut off to one of three wires that transmit energy to the inverters and to customer homes and businesses.
Pictured: Our Data Acquisition System, or “DAS”, being installed at Springfield. The DAS gathers information from equipment and a weather station so we can monitor the system performance remotely.
Once these steps are completed and we have our official “permission to operate” certificate from the utility, we are considered interconnected. Panels will begin contributing solar energy to the grid and shortly thereafter customers will begin seeing credits on their electric bills.
Stay tuned for our next construction check-in where we will share the latest photos and timelines for each of the sites!
To read previous CEC-SCE&G updates on our South Carolina projects, please see these posts: