Workplace safety strategies to know when installing and maintaining solar projects
By Jeffrey R. Jowett, senior application engineer, Megger
Workplace safety is important in every area. Knowing how to properly use tools, equipment, and machinery, and wearing all the necessary safety equipment to do your job, can help you avoid damaging equipment or being seriously injured. This is especially true when dealing with the power grid, such as installing and maintaining PV systems.
When designing, installing, and maintaining PV systems, workers must pay close attention to strict guidelines and directions to help reduce or eliminate installation errors, electrical faults, and injuries. The power coming out of these systems can be erratic at times and hazards can be hidden in things like ground faults or wiring. Knowing best practices and what to look for can help mitigate the risks.
What can go wrong
Workers in the solar energy industry are exposed to a variety of serious hazards when working with PV systems. These hazards include arc flash, which is when there is a powerful discharge of electricity between two or more conductors that can cause burns or even death; as well as deterioration of the insulation that can cause a fire; electric shock from loose system or tool wiring and wiring that is not grounded or double insulated; thermal burns that can cause serious injury or death; as well as falling.
When it comes to solar electrical systems, there are two sources of electricity: the utility company and the solar electrical system. Simply turning off a main switch doesn’t stop a solar electrical system from producing power. Modules always have some kind of voltage, even in low light. Improper use could result in a shock or arc flash, which could result in serious injury or death.
Where Problems Occur
In PV systems, most of the problems occur in the combiner box, the PV source and output circuit conductors, and the equipment grounding conductor. But problems can be avoided if workers take the time to install and maintain them properly. After installation, maintenance is required at least every two years, especially if the modules are tilted. When modules are moved out of line due to natural events such as weather and damage from human or animal contact, the efficiency of the string/array is affected. Misalignment can lead to unfavorable production in the array with regard to maximum power delivery to the grid. The alignment must be corrected with an IR radiation tool such as the Megger PVM210 to return the module to maximum efficiency alignment. There are monitoring apps that can help owners keep track of the amount of solar energy the modules are producing. If there seems to be a dip in production, it’s either time to clean the modules or look further to see if there are other issues going on.
Identify a problem before it occurs
O&M technicians can use a variety of tools to troubleshoot an array. These include a digital clamp meter, irradiation sensor, insulation resistance tester and a thermal camera. Each tool has a specific job of identifying problem areas, helping to solve the problem and protecting employees.
Digital clamp meter
A digital clamp meter measures the output voltage of PV modules to verify the performance of a PV array. It also allows solar technicians to test higher voltages and currents with greater flexibility using a single instrument. Using this tool, technicians can measure the intensity of sunlight hitting the arrays. This measurement is very important when validating the performance of a PV system.
This portable tool measures the intensity of sunlight hitting an array. Measuring solar radiation provides knowledge when making important decisions about future energy yield, efficiency, performance and maintenance.
Insulation Resistance Tester:
An insulation resistance tester helps perform insulation resistance tests during start-up and maintenance activities to verify the integrity of conductors associated with a photovoltaic array. This tool can be used in residential, commercial and industrial rooftops, as well as large-scale ground-based solar applications.
Periodic testing of PV system electrical cabling and components helps to indicate system health, early identification of potential problems, ensure safe system operation, and reduce the risk of fire associated with potential or existing electrical faults to decrease.
A thermal camera helps to quickly and safely assess the PV modules as well as the junction boxes, combiner boxes and electrical connections for abnormal heat with a quick scan. The camera is used to locate bad cells, wiring, or diodes. Each of these plays an important role in making the PV generator work properly.
Cells are connected in series. When one cell in the array fails, no current flows through that entire array, so no electricity is generated. If an array is incorrectly wired or defective, it may not provide the correct voltage and power up electrical units or fully charge the battery bank. If a diode has failed, users will notice a drop in output.
Megger offers a Solar Test Kit with each of these tools to make a technician’s job easier.
Understanding PV systems, the hazards that lurk and how to safely test and maintain them is essential to protect both employees and end users.