Why are batteries used in a solar PV system?

Batteries are used in PV systems to store energy and utilize it when available solar power may not be enough to power the desired load. While lead-acid batteries such as flooded electrolyte, gel electrolyte, Sealed Maintenance Free (SMF), etc. are commonly used due to lower cost and high availability, other batteries such as lithium-ion are also gaining popularity. Batteries are sized based on power and energy requirement of the load and often oversized to provide autonomy during cloudy days. We scrutinize batteries not only in terms of energy density but also longevity, load characteristics, maintenance requirements, self-discharge, and operational costs.

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What are the important points to be observed during a battery inspection?

The goal of battery care and maintenance is to improve the battery’s performance and life. Battery life is a highly variable property that depends on a host of factors such as storage temperature and depth of discharge (DOD). The following needs to be observed during a battery inspection: Terminal rusting is the main problem of all batteries. Rusting in terminals reduces the current flow to and from the battery. This will considerably affect the life of battery and inverter efficiency. Maintenance-free batteries also need care against rusting in terminals. Contacts affected by rust restrict the charging current and slow down the rate of charging, which in turn reduces the life of the battery with irreversible. Battery sulfation (external, on the connector) Clean the battery terminals at least once a month. About 80% of failures are caused by sulfation (a process where sulphur crystals form on the battery’s lead plates and prevent chemical reactions from happening). When the battery has a low charge or electrolyte level then sulfation occurs. Thus, it is very important to monitor, maintain and control sulfation in flooded batteries. To do this you will need distilled water, digital voltmeter, temperature compensating hydrometer and proper safety gear. (Ref: Best Practices in Operation and Maintenance of Rooftop Solar PV Systems in India – GERMI)

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What are the checks to be performed during inspection and maintenance of cables?

The following checks must be performed during inspection & maintenance: Check for cable routing. The cables shall be routed properly and fastened with clamps to avoid damage to the cables. Often times we notice that cables are not properly routed and the cable wires are left hanging. This may cause damage to cables due to rodents, squirrels, and other pests or can cause a hazard when people walk around the terrace. Fig – Improper cable routing Closed Loops and open loops. Many at times we notice that cables are not properly looped. Sometimes the cable loops are very tight or very loose. A loose connection may lead to a fire hazard and tight connections may lead to breakage of the cable. Fig – Cables looped loosely Check that all cable connections are tightened and securely fastened. Check that all cables are properly insulated, without insulation damage. Check for quality of outer sheath and conductor insulation. Check whether separate single-core cables have been used for the positive and negative conductors of dc circuits. Check whether unused cable entries have been closed. All unused cable and conduit openings shall be plugged with blind plugs or caps to prevent the entry of dust, insects, squirrels, rats and other pests. Check for the quality of conduits (diameter, wall thickness) Fig – Damaged conduits Electrical rooms, niches, switchboards, and distribution boards shall be kept clean and neat. The immediate surroundings of all electrical systems shall be kept clean and free to allow access at any time. Check […]

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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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When should you install a rooftop solar system?

Though installing a solar PV system has multiple advantages, the installation is a comparatively large investment to make. Thus prior to approaching any installer, it is crucial that the consumer should check if it fulfills the following prerequisites: Roof rights: As the solar PV system would preferably continue to generate electricity for 20-25 years, the consumer has to check if she/he has the right to use the rooftops for installing the solar PV system. Location: The performance of the solar PV system would depend on the amount of direct sunlight the system receives. Thus the consumer has to check if the nearby buildings/ trees do not cast any major shadows throughout the day. How long are you are going to live in your house? Though you will see an immediate reduction in your electricity bill after installing a PV system, however, it will take 4-5 years to recover the initial capital invested. Thus you may install a PV system if you plan to stay in the same house for the long term. Type of roof: This is an important aspect to consider before installing a PV system. The solar panels can be installed on almost each and every rooftop. However, the type of roof may have an effect on the effort and the cost of the structure. If you happen to use terracotta shingles, you may need to find the installer who is experienced and skilled enough to work with such types of rooftops. Did you check the above preconditions […]

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What to check in the proposal provided by the Installer.

Before selecting the installer for setting up a solar PV system, it is important to check the following from the proposals submitted by the installer. Minimum generation guarantee: The solar PV system generates electricity and must be warranted by a minimum generation guarantee. The minimum generation depends on a number of factors including the location, design orientation etc. and should be provided by the installer during feasibility analysis. The consumer should compare the minimum generation guarantee and the compensation rate offered by the installer.   

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What is earthing and why is it important in a rooftop solar power plant?

Earthing refers to a safety system designed to protect electrical wires and components from damage caused by sudden electrical power surges. The aim of earthing in electrical installations and circuits is to enhance the safety of the installation by reducing the level of danger inherent to fault currents. Fault currents may be caused by different factors. Therefore, it is very important to design an earthing system according to the installation’s characteristics.  Earthing system is important because it provides: – Safety for humans from electric shocks; – Protects the installation and equipment itself from any damage; – Safety from atmospheric electricity (lightning) etc.  

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What are the general safety rules to minimize risk before, during and post-installation?

Safety should always be a priority during any installation. Although, most of the safety aspects and technical standards are followed by the manufactures and installers of the rooftop solar power plants, there are a few general safety rules that one should know to minimize risk in a solar power plant before, during and post-installation. Pre-installation PV module installation area/roof must be thoroughly inspected by the installer for possible electrical, chemical, fire etc. hazards before installation The roof where the solar power plant is being installed should be strong enough to support the weight of the plant to avoid future damage Never install a PV power plant near chimneys or flame outlets that could damage the PV modules PV module should be designed with safe lines (wherever needed) so that the maintenance and cleaning of the PV modules can be done safely During installation PV modules or other PV components should not be installed during bad weather. PV modules can be blown around by the wind or a storm which can result in you falling or damage to the PV system and nearby objects and even injury to humans Always ensure that extreme safety precautions (including body harnesses, lifelines and safety nets) are used by the installer to prevent slipping, falling and causing injury when working, especially at height Make sure the area underneath the installed PV modules is clean, clear and free of foreign objects which prevents from water logging Make sure your entire solar power plant is properly and […]

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Module Mounting Structure

A module mounting structure (MMS) is the supporting structure that holds the PV modules to the roof or ground and provides the desired tilt angle for a maximum generation it is designed for. The type of MMS design is based on the surface of installation i.e. Iron, RCC or Asbestos roof. Generally, module mounting structures are of three types: Hot Dip Galvanized Iron (GI) Aluminium Mild Steel (MS) Various rigorous structural analysis and tests for protection against wind and also for the mechanical strength of the MMS to guarantee the safety and stability of the mounting structures are required to be conducted before installation.

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Do concrete roofs and metal roofs have different mounting structure?

Solar PV modules can be installed on almost all kinds of rooftops. The complexities involved in installing a PV module may differ with different rooftops, type of roof construction and roof strength. Therefore there are different PV module mounting structures for metal roofs and flat concrete roofs. Some of the examples of commonly used mounting structures based on the roof type are mentioned below. Flat concrete roofs (example RCC) Concrete roofs are in general the easiest way to install a solar power plant as the access for installation and later operations and maintenance if very easy. Depending on the roof design and shadow-free area the common type of module mounting structures for concrete roofs are highlighted below: 1. Low elevation ballast structures  This type of structures are designed for flat roofs with limited load capacity and where there are no shadow issues. The design of the system includes a windshield (sloped wind deflector) that seals the system and reduces the suction force of the wind on the PV modules making the installation stable under high wind load and prevents the frame from overturning/lifting. Typically such mounting structures have a tilt angle of not more than 15 degrees. 2. Elevated ballast structure This type of structures are advised for flat RCC roofs which have shading issues. These structures can be designed for high ground clearance and can easily combat heavy wind loads. These structures are also designed for installation with penetration to the roof; however, it is not recommended. Instead ballast-based […]

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