Solar panels react differently to the operating temperature. The efficiency of a solar panel decreases as it increases above the ambient temperature. Each solar panel has a temperature coefficient (which is defined in datasheet of panels). The temperature coefficient represents the rate at which the panel will underperform at each increase in degree Celsius (°C). Most panels have a temperature coefficient of between -0.2% /°C to -0.5%/°C, when tested under standard laboratory conditions, where ambient temperature is set to 25°C. For example if the temperature coefficient of a particular type of panel is -0.5%, then for every 10C rise, the panel’s output power will reduce by 0.5%. [Source: Youtube] [Publisher: altE Store’s Educational Video Channel]
The aim of earthing is to enhance the safety of the installation of solar plant by reducing the level of danger inherent to fault currents. Earthing prevents damage to the components as a result of flow of heavy fault currents. For rooftop solar plants earthing is done on both DC side as well as AC side covering components of the plant like modules, inverter, structure & lightning arrester.
Solar DC cables interconnect solar panels to the combiner boxes to inverter. The DC cables are usually two-core cables, a current-carrying live red wire and a negative blue wire, both are typically surrounded by an insulation layer. DC cables are generally made of copper conductors which provides more flexibility. As the life of the solar plant is expected to be more than 25 years, DC cables should be capable to withstand high temperatures, UV radiations, fire risk, expose to water etc.
Hot Dip Galvanizing is the process of applying a zinc coating to fabricated iron structure by immersing the structure in a bath consisting primarily of molten zinc. The galvanizing prevents the corrosion of the iron structure by providing a tough metallic zinc envelope, which completely covers the surface of the structure and seals it from the corrosive action of its environment. Hot-dip galvanizing involves three main steps: Preparation: The galvanizing reaction can only occur on a chemically clean surface, so the first step of the process involves removing any contamination on surface of the iron structure. Galvanizing: The clean iron structure is dipped into the molten zinc, and held there until the temperature of the iron quilibrates with that of the bath. The structure is then pulled-out & allowed to cool. Inspection: After galvanizing, the coated materials are inspected for coating thickness, uniformity and coating appearance. It is advisable to have galvanization post-fabrication of the structure in order to avoid any damage to the galvanized layer. The thickness of galvanization varies from 40 -150 micros depending on the local site conditions and requirements.
In India, the local utility company/DISCOM is responsible to establish net-metering for grid connected rooftop solar plants. The local utility company or the DISCOM first reviews the application for net-metering and requisite project related documents submitted by the consumer or the installer of the solar plant and provides approval, if the project is feasible based on the capacity of local distribution transformer & the design documents, components etc. of the system are inline with their requirements. Once that the project is approved & the plant is installed, the Net-Meter is installed by the local utility company/DISCOM.
Depending on the state regulations, the DISCOM or the consumer procures the net-meter as per the energy meter standards specified in the state regulation. The testing of the net-meter & installation at the consumer premises is done by the respective DISCOM.
What would happen if the solar panels deployed in the system have different electrical characteristics?
When solar panels with different electrical characteristics, interconnected with each other are deployed in the system, it creates serious power losses & adversely affects the overall energy generation. These losses are referred as “Mismatch losses”. The current (Isc) in the string in which the panels are connected in series with each other, is limited to the lowest output current from any of the panel. Thus mismatch causes the lower output power from the string & the system efficiency and performance becomes lower.
The performance of the solar panel is affected by its tilt angle and orientation with respect to the horizontal plane. Orienting the solar panel in a direction and tilt to maximize its exposure to direct sunlight can ensure a better generation. The solar panel collects solar radiation most efficiently when the sun’s rays are perpendicular to the panel’s surface. Solar panels should always face south if the plant is in the northern hemisphere, or north if the plant is in the southern hemisphere & the tilt of the solar panels should be proportionate to the latitude of the plant site to optimize their power generation throughout the year. The installer of the plant analyses the optimum tilt & orientation before installing the solar plant. [Source: Youtube] [Publisher: altE Store’s Educational Video Channel]
Weather conditions are unlike in each location. As solar plants are installed around the world, solar panel manufacturers test their products to ensure that they are dust & storm resistant, salt mist & ammonia corrosion resistant, capable to withstand hail storms & heavy snow loads & extreme temperature variations. The junction box attached with the modules are made waterproof.
When one (or more) solar photovoltaic cells becomes faulty or provides no power due to shading, the current then flows through the solar bypass diode and prevents hot spots and losses in yield. When part of a photovoltaic panel is shaded, the shaded cells will not be able to produce as much current as of the unshaded cells. Since all cells are connected in series, the same amount of current must flow through every cell. The unshaded cells will force the shaded cells to pass more current. This causes the solar panel to heat up, have a severe power loss. As a result, those shaded solar cells become consumers of electricity instead of producers. The function of bypass diode is, when a cell or a panel becomes shaded its bypass diode becomes “forward biased” and begins to conduct current through itself. The effected portion of the solar panel is bypassed, thus drastically reducing the amount of local heating & current loss at the shaded area. [Source: Youtube] [Publisher: altE Store’s Educational Video Channel]