Metering configurations for Rooftop Solar Power Plants

There are two common types of metering arrangements available for solar PV Installations. net-metering gross metering Selection of the metering configuration that best suits the consumer depends upon on the purpose of solar PV system installation and state regulations. General utility metering arrangement A general utility metering arrangement caters electricity supplied through the utility grid to a consumer via power distribution lines. The utility installs an energy meter to monitor and record the consumption i.e. the amount of electricity imported by the consumer. Net metering Net metering is a utility billing mechanism that allows the consumer to export the surplus solar generation from grid-connected solar PV system into the utility grid. This arrangement changes the consumer interaction with the utility from a one-way relationship to a two-way relationship. With net metering, the consumer not only imports the electricity from the grid but also gains the ability to export the electricity to the grid which is recorded by a bi-directional energy meter installed by the utility. A solar PV system can often generate more electricity than one consumes during daylight hours. This combination of high output and low usage results in surplus power. With net metering, the consumer can export this surplus electricity during daytime to the utility grid and consume the electricity when solar system is not generating. Therefore, with the net-metering arrangement, a consumer is only billed for the “net” energy used, i.e. the difference between the energy produced by the solar PV power system and the energy consumed over the […] Read more

What are PV module hot spots, its causes and effects?

Hot spots are areas of high temperature that affect only one zone of the solar panel and resulting in a localized decrease in efficiency, and therefore, lower output power and accelerated material degradation in the area affected by the high temperature. Hot spots are not visible to human eyes and are detected and verified using infrared measurement technique. Above image shows of a solar panel showing a hot spot developed due to bird droppings Causes and its effects The reasons for the appearance of hot spots are multiple and can be classified into functional or operational. Defect severity and remediation actions also vary widely as a result. Functional reasons Cell mismatch: It occurs when cells of different current are connected in series. Cell damage: It occurs during manufacture, due to the fact that the silicon cell will be subjected to a stressful process during rolling, handling and transportation. Operational reasons Seasonal shadows: When cells are completely or partially shaded for a long period of time, it results in increased temperature in the shaded cell and further creates hot spots. The loss in power output due to a hot spot in solar panels is not directly correlated with the area of the panel that is shadowed. Even a small shade can have a significant impact on the output power of the module. Soiling or dirt accumulation: Solar panels become dirty from dust, suspended sand, dirt and other contaminating impurities if not cleaned periodically during their service life. The dust accumulated on the […] Read more

Why solar plants needs to be earthed?

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. Like this:Like Loading... Read more

What are solar DC cables?

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. Like this:Like Loading... Read more

What is a Hot-Dip Galvanized Iron (GI) structure?

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. Like this:Like Loading... Read more

How is the Net-Metering of grid connected rooftop solar plant is established?

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. Like this:Like Loading... Read more

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