With fossil fuels shrinking worldwide, the demand for alternative fuel sources has given rise to more demand for Solar PVs. Today we have both governments and private enterprises investing solar PVs. This has also given boost to suppliers of solar PV systems like solar cables manufacturers. When we talk about solar PVs we are usually focused on its constituent parts like the inverter, substructure and the modules. We often ignore the solar cables, which are one of the most important components. Without the right cable, we will not be able to get the best out of the system and can malfunction.
Solar Cable Function
A solar cable is used in photovoltaic power production. The cables act as interconnecting units between the solar panels and the electric components of the photovoltaic system. The main components are solar panels, batteries, charge controller, and the inverter. As part of a solar PVs system, these cables are obviously required to be laid outside. This also means a high ability to withstand atmospheric conditions, such as exposure to UV rays, wide range of temperatures.
In a PV system, the solar panel faces the sun so as to catch the solar energy. This solar energy is converted to DC current, which is then carried by the solar cables to the storage batteries. While the DC current is ready for use, in India there is a preference for AC current. Hence, the DC current is converted to AC current by an inverter. So, the cables are an important part of the process, ensuring that the current flows from one component to the other.
A solar PV could be a standalone module or part of a larger system. In a larger PV system, the solar cables connect all the solar modules to form a PV generator. These solar cables are also known as string generators.
Many of us may have seen the solo solar PVs on rooftop. These are run on lower voltage when compared to the grid-connected systems. Other than high voltage, grid PVs have other components which require these units to be installed in a separate, isolated locations like most power grids.
Needless to say, the system has many solar cables that connect various parts to each other. The DC cable connects the inverter to the generator junction box. The DC current produced in the PV module has a low voltage with high current. This makes the DC cable different form the other solar cables in the system. Given the high current it has to carry, the cable must be selected carefully.
For the DC cables, the solar cables manufacturers have to pay particular attention to the sizing of the cable system. This has a direct affect on its efficiency and safety. Some of the perils of choosing the wrong size are:
- Overheating, which can then cause fire?
- Increase in size will mean higher cable resistance. Even a small increase in resistance can mean a significant loss of energy.
The sizing of the cable also depends on the distance. The further the panels are from other components, the larger the wire gauge should be.
Basic Requirements from Solar Cables:
One of the common features of all solar cables is that these are always laid in an outdoor location. This means that solar cable manufacturers must ensure that the cables are able to withstand the corrosive effects of an outdoor location. The cables can:
- Withstand UV radiation
- Withstand moisture
- Tolerate temperature fluctuations
In addition the cables must have a high flexibility, since these must move with the panels. To ensure this, most solar cables have class 5 flexible heavy duty tin coated copper conductor. The insulation and over-sheath has a low smoke, halogen free structure. To ensure protection against UV rays, it is black in color. The cross-linked polymer in the sheath ensures protection against temperature fluctuations.
Protection against temperature fluctuations is important because solar cables are laid in outdoor conditions. This means that the cable must be protected against both high and low temperatures. This is also why the cables need protection against UV rays. This ability to withstand environmental conditions is what gives the cable its durability and is responsible for its unique construction.
Solar cables have a very important role to play in solar PV systems. Given the tough conditions that solar cables function in, solar cable manufacturers are required to make the cables under very strict specifications.