What is the function of bypass diode in solar panels?

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]

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What is the solar panel efficiency?

The solar panel efficiency or conversion efficiency is the percentage of the solar energy striking on the panel that is converted into usable electricity. Not all of the sunlight that reaches a photovoltaic cell is converted into electricity. When light strikes the surface of a solar cell, some photons are reflected, while others pass right through, some of the absorbed photons have their energy turned into heat & the remainder have the right amount of energy to separate electrons from their atomic bonds to produce charge carriers and electric current. Most solar panels provide an energy efficiency rating between 11 to 18 percent, which is the percentage of solar energy that is being converted into usable electricity. A solar panel specification sheet usually contains a panel efficiency value at Standard Test Conditions(cell temperature of 25°C and an irradiance of 1000 W/m2). The higher the efficiency rating, the less number of panels you’ll need to make up a system that meets your energy requirements. However, choosing a more efficient solar panel may not always be the most cost-effective decision available.

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What is the effect of shading on a solar power plant?

Shading has a huge impact on the performance of solar photovoltaic panels. Solar power plants generate electricity proportionate to the amount of sunlight they receive. Therefore, when a shadow is cast on panels due to any obstruction in the path of sunlight falling on the panels, the power output decreases substantially. In fact, the solar photovoltaic panels consist of a number of cells which are connected together into a series circuit. Because of this, the performance of the solar panel is significantly reduced even if a smallest section of the panel is in shade. Another issue from partial shading is overheating. Because of partial shading a part of the solar panel generates lower amount of energy as compared to the other non-shaded part. As the amount of power generated from shaded & non-shaded parts differs, it leads to overheating, hot-spot creation & causing irreversible damage of the cells, which in turn reduces the total power output of the solar panel. Depending on the location of the object, the shading may be seasonal or for a few hours each day resulting in fluctuations in the power. The performance of solar  panels is affected by the shading effect due to trees, neighboring buildings, vegetation, poles and any other means. [Source: Youtube] [Publisher: altE Store’s Educational Video Channel]

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What are the major classifications of solar panels?

There are 3 major types of solar panels: 1. Monocrystalline 2. Polycrystalline 3. Thin Film 1. Monocrystalline Monocrystalline panels are the most efficient solar panels. They are made out of silicon ingots of very high purity. The silicon ingots are cut into thin wafers which are mounted in a grid shape. One can easily recognize them from the uniform dark look and the rounded edges. The silicon’s high purity causes this type of solar panel to have the highest efficiency rates. Monocrystalline panels have higher efficiencies, occupy less space but that also means they are the most expensive solar panels.   2. Polycrystalline Polycrystalline panels use melted silicon, which is poured and cut into perfectly square wafers. This melting process uses just about all the material, eliminating abundant waste during manufacturing. Polycrystalline panels  are the most commonly used type of panel for both residential and commercial installations. Their efficiency is slightly lower and are lesser expensive as compared to monocrystalline panels. 3. Thin Film Thin-film solar panels are not necessarily made from silicon like other panel varieties. These solar panels use alternative photovoltaic mediums that are deposited in a thin layer over a substrate. Thin-film solar panels are most often manufactured from cadmium telluride (CdTe), amorphous silicon (a-Si), copper indium gallium selenide (CIS/CIGS) etc. They are not as efficient as polycrystalline or monocrystalline panels and have large space requirements but can be made flexible, thus have numerous potential applications. These types of solar panels are the easiest to produce and economies […]

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How to clean PV modules of my rooftop solar plant?

There are two methods for cleaning solar PV modules: Dry Cleaning Wet Cleaning   Dry Cleaning In this method of cleaning, a brush, sponge or a cloth is used to clean the surface of the modules without using water or any other liquid. The brush or cloth must not be rubbed vigorously as it may can result in scratches on the surface of the PV module. Dry cleaning may not be suitable for tough strains such as bird-droppings, dead insects, tar etc. Wet Cleaning In this method of cleaning, water is used to eliminate dirt from the surface of the solar PV module. It is done by using a soft cloth, brush, detergent(non-abrasive) and clean water. Few recommendations for wet-cleaning of solar modules: Cleaning time: The recommended time for cleaning modules is during low light conditions when production is lowest. The best time to clean modules is from dusk to dawn when the plant is not in operation and risk of electrical shock hazard is minimum. Quality of water: The water must be free from any suspended particles that could damage the module surface. De-ionized water is preferable for cleaning the modules. If de-ionized water is not available, tapwater or rainwater can also be used Use of cleaning agent: A mild, non-abrasive, non-caustic detergent with water may be used. De-greasers, Acid or alkali detergent should not be used Removing stubborn marks: To remove stubborn dirt such as birds dropping, dead insects, tar etc., use a soft sponge, micro-fiber cloth or non-abrasive brush. Rinse the module […]

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What are different kinds of inverters used in solar power plants?

Broadly, the solar inverters can be categorized in the following types: Grid Connected Inverters Grid connected inverters are simply inverters which are connected to the grid. These inverters produce a sine wave that is congruent with the AC waveform produced by the grid. They allow you to send surplus solar electricity, your system has generated back into the grid. Grid connected inverters have Anti-islanding feature which allows the inverter to realize the sudden change in system frequency, voltage, rate change of frequency, increase in kW beyond normal levels, or a change in kVAR and shut down the inverter. When the inverter shuts down your system is no longer producing electricity for the safety of the people who will be working on the grid to repair it. Grid connected inverters are sub categorized as follows: Central Inverter: These inverters are typically used for large scale projects (usually above 250kW). They are huge, have their own rooms with exhaust, etc. They are  are cheaper than string inverters & requires low maintenance due to lesser terminations on AC side. String Inverter: This is the most commonly used solar inverter for homes and business consumers. They are much lighter and resistant to harsh atmospheric conditions. String inverters are based on modularization, each PV string goes through an inverter, with maximum power tracking peak at the DC terminal, and grid-tied at the AC side. Micro Inverter: Micro-inverters are small sized inverters attached to individual solar panels. They use power point tracking,  which means essentially if […]

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Checklist of Documents for Net Metering


What is Capacity Utilization Factor (CUF) in context of rooftop solar plants?

Capacity Utilization Factor (CUF) is the ratio of actual energy generated by rooftop solar plant over the year to the equivalent energy output at its rated capacity. CUF % = annual energy generation from the plant in kWh x 100 / (installed plant capacity in kW x 365 x 24) Minimum CUF is either defined by the state nodal agencies in their tender documents or the installer of the plant or the contractor for operation & maintenance can evaluate the minimum CUF based on the components deployed & local site & environment conditions.

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Do I have any obligations, as an owner of the rooftop solar plant, after I sign an operation & maintenance contract?

After signing the operation & maintenance contract with the contractor, the owner of the rooftop solar plant has following obligations: Information: In order for Contractor to adhere to any Project Contracts on behalf of Owner, Owner should provide Contractor with all manufacturer’s manuals, spare parts lists, plant data books and drawings, or any part thereof. Owner shall also provide Contractor with copies of all Project agreements and any amendments thereto and any other documents that define the plant’s operating requirements; Access to Plant: The Owner shall provide Contractor and its employees with access to the roof where the RTS Plant has been installed – as required for the performance of Contractor’s duties under this Contract. The Contractor shall schedule maintenance in advance with the Owner; Provision of water & Electricity: The Owner should provide water & electricity free of cost for maintenance purpose to the Contractor; Notice of Damage: Owner shall promptly notify Contractor if Owner becomes aware of any damage to or loss of the use of the RTS Plant; Periodic statutory clearances: Necessary statutory approvals on timely basis as may be required from the competent authorities like Chief Electrical Inspector approval, shall be arranged by the owner of the plant;

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How should the disputes be resolved, if arises between the owner of the plant & contractor responsible for operation & maintenance?

If any dispute arises between Owner and Contractor, the parties shall attempt to settle such dispute in the first instance through discussions. The designated representatives of Owner and Contractor shall promptly confer and exert their best efforts in good faith to reach a reasonable and equitable resolution of such dispute.  If the representatives are unable to resolve the dispute, the dispute shall be referred to the responsible senior management of each party for resolution.  If the parties are unable to resolve the dispute, either party may pursue any remedy available at law.

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