What is an electrical earthing protection?

Earthing is the method of transmitting instant electricity discharge directly to the ground through low resistance wires or electrical cables. It is basically a system designed to protect electrical wires and components from damage caused by sudden electrical power surges. Earthing systems also prevent personnel from electrical shocks in the event of a short circuit. Regardless of system voltage, earthing is required on all solar PV power plants. Its main purpose is to reduce the risk of dangerous electrical shocks to the installer or the user from uninsulated metal parts of a plant. There are two common types of earthing done in solar PV power plants: Equipment earthing – The basic objective of equipment earthing is human safety by preventing the surge of current to an unsafe level. In this metallic body of equipment / devices is connected to the grounding grid to prevent electric shocks to any personnel touching that equipment or device. System earthing – The system earthing is also referred to as neutral earthing. Under this, neutral of the electrical system is directly connected to the earth. Earthing in a solar PV power plant  A rooftop solar power plant earthing is usually divided into two parts based on its electrical construction, AC side and DC side. DC Earthing – These parts cover the equipment in the DC side of the electrical circuit, such as PV modules, module mounting structures, DC junction box, DC Monitoring Box (if any), etc. AC Earthing – These parts cover the equipment in […]

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What is anti-islanding protection?

Anti-islanding protection is a way for the grid-connected solar inverter to sense when there is a problem with the utility grid, such as a power outage, and shut itself down to stop feeding solar power to the grid. Anti-islanding protection is a mandatory required safety feature that is built into all grid-tied and hybrid inverters that operate in India and various other counties across the globe including US, Germany, etc. This protection feature is required because in case of power failure or outage the utility needs the power lines to be completely safe for maintenance. Some of the regulatory requirements in India for anti-islanding are as follows: according to IEEE 1547 and  Central Electricity Authority of India (technical standards for connectivity of the distributed generation resources) Regulation 2013 – for an unintentional island the grid-tied inverter shall detect the island and cease to energize within two seconds of the formation of an island. according to IEEE 1547 the grid-connected rooftop solar system shall include an adjustable delay (or a fixed delay of five minutes) that may delay reconnection for up to five minutes after the grid voltage and frequency is restored. As per Central Electricity Authority of India Regulation, 2013 the delay shall be for at least 60 seconds.   The post ID for this chapter is 2741. For any suggestion or comment regarding the content, you may write to us at faqs[dot]solar[at]gmail[dot]com. Please quote the post ID in the subject, for better assistance.

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Why should the length of a shadow be considered while identifying PV array location?

The size of a shadow depends on: size of the object location of the object date and time of the day Taking these into account, the length of a shadow should be estimated accurately when designing a solar system so that row spacing between solar PV modules can be properly decided. Keeping in mind that the sun travels in an arch, therefore both the sun’s altitude (position) and the azimuth must be considered when determining the length of a shadow.    

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About Phase-II of Grid Connected Rooftop Solar Programme

Ministry of New and Renewable Energy (MNRE), Government of India has launched the Phase-II of Grid Connected Rooftop Solar Programme that provides a subsidy for installing rooftop solar systems. The programme is being implemented through electricity distribution companies and provides a subsidy for the household owner and Group Housing Societies to set up solar systems on the rooftop of their residence/residential campus. 40% subsidy will be provided for installing a rooftop solar system of up to 3kW capacity; 20% subsidy is available for installing a rooftop solar system beyond 3kW and up to 10kW capacity; 20% subsidy will be provided for Group Housing Societies/Residential Welfare Associations for installations up to 500 kW (at 10 kW per house) for common facilities. Click Here to study the Operational Guidelines on implementation of Phase – II of Grid Connected Rooftop Solar Programme. Note: Subsidy benefit from MNRE is available for the residential sector only.        

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Technical feasibility (Shading Assessment)

A crucial step in preparation to installation of solar PV plants is the shading assessment. The shading analysis is detrimental because the performance of a PV module is heavily dependent on the amount of exposure it receives throughout the day and the year. Shading can damage a PV panel by creating hotspots and as panels are mostly arranged in arrays, damage to one panel will have a ripple effect on the entire array. Let us read further to understand the importance of shadow analysis. What are the different types of shadings that affect solar PV modules? The different types of shadings that affect solar PV panels are solid shadows, partial shadows and partial shading due to improper cleaning. What is shadow analysis and why is it important? Shadow analysis is the assessment of the site of installation of the solar PV modules for the casting of shadows. This technical analysis is of utmost importance before proceeding with installation because the casting of shadows on a solar PV module has a considerable impact on its efficiency and shelf-life.  The effect of shading is to reduce the photocurrent per unit area of the cell. A shadow falling on a solar PV module blocks the flow of solar energy and eventually, the modules generate hotspots and are damaged through the rise in temperature. The shading could be of nearby trees, buildings or even inner-row shading of the installed PV module array. The efficiency of a PV module at any time reduces in direct […]

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What are the major types of solar PV modules?

There are three major types of solar PV modules. Mono-crystalline Poly-crystalline (also known as multi-crystalline) Thin-film Each solar PV module type has its own unique features. These PV modules also vary based on how they’re manufactured, their appearance, performance, costs each are best suited for. Mono-crystalline and Poly-crystalline solar PV modules Both mono-crystalline and poly-crystalline solar PV modules have cells made of silicon wafers. To build a mono-crystalline or poly-crystalline module, wafers are assembled into rows and columns covered with a glass sheet, and framed together. Poly-crystalline cells are square-shaped whereas mono-crystalline cells are square with missing corners. While both of these types of solar PV modules have cells made from silicon, mono-crystalline and poly-crystalline modules vary in the composition of the silicon itself. Mono-crystalline solar cells are cut from a single, pure crystal of silicon. Alternatively, poly-crystalline solar cells are composed of fragments of silicon crystals that are melted together in a mold before being cut into wafers. Mono-crystalline modules typically have the highest efficiencies and power capacity. Thin-film solar PV modules Unlike mono-crystalline and poly-crystalline solar PV modules, thin-film modules are made from a variety of materials. The most prevalent type of thin-film solar module is made from cadmium telluride (CdTe). To make this type of thin-film module, manufacturers place a layer of CdTe between transparent conducting layers that help capture sunlight. This type of thin-film technology also has a glass layer on the top for protection. Other materials used to manufacture a thin-film PV module are amorphous […]

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What are the components of a Solar PV Module?

PV Module Frame PV Module Glass PV Module Encapsulant PV Module Back sheet PV Module Junction Box    

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What are the components of a grid connected Solar PV power plant?


Introduction to Feasibility analysis

Feasibility analysis is imperative to assess the viability for any project before allotting time, budget and resources to it. Analyzing feasibility is always beneficial as it provides a clear picture of the proposed project to all its stakeholders. An efficient feasibility study will ensure the success of a project. In case of rooftop solar installation, the installer has to conduct feasibility assessment majorly on the technical, regulatory and economic aspects. Bigger projects require formal feasibility evaluation, for smaller projects checking main feasibility factors by the installer should be sufficient. The feasibility, even of the small project, should be evaluated in three aspects: technical, legal and financial. Technical feasibility evaluates the technical requirements that would be necessary for installation. For e.g., the capacity of the plant required for power generation, technical resources available to support installation and capacity generation, roof construction etc. Regulatory feasibility assesses the regulatory adherence of the project. For e.g., whether the client possesses roof rights, environmental regulations of the locality, etc. Financial feasibility evaluates whether an installation is financially viable when cost and benefits associated are compared. For e.g., the investment required, the payback period, etc. For bigger projects, economic feasibility check is required. The project is economically feasible when it provides more economic benefits than harm – for example, solar power plants (besides direct benefits to owners) mitigate global warming problems, diversify energy sources, can generate local market etc.

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Lesson-4

The goal of this lesson is to provide information which is necessary to understand general and specific safety practices and its importance in solar PV installation, operations and maintenance. By the end of this lesson, the reader should be able to understand the need for safety, various workplace hazards, how to identify hazards, personal protective equipment, safe workmanship and safety equipment that should be installed in a rooftop solar PV power plant for safe operations.

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