Chapter 4- Solar Panel

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Study of Solar Module & Its Efficient Use in Bangladesh

3Solar Panel

Chapter 04

SOLAR PANEL

04.1 Introduction

Solar panels (arrays of photovoltaic cells) make use of renewable energy from the sun,and are a clean and environmentally sound means of collecting solar energy. Here atsolar panel information, we've amassed a wealth of information relating to solar panelsand the field of photovoltaic technology. Solar Panels are a form of active solar power, aterm that describes how solar panels make use of the sun's energy: solar panels harvestsunlight and actively convert it to electricity. Solar Cells, or photovoltaic cells, arearranged in a grid-like pattern on the surface of the solar panel. These solar voltaic cellscollect sunlight during the daylight hours and convert it into electricity.

04.2 Solar Panel Construction

Solar panels are typically constructed with crystalline silicon, which is used in otherindustries (such as the microprocessor industry), and the more expensive galliumarsenide, which is produced exclusively for use in photovoltaic (solar) cells.

Other, more efficient solar panels are assembled by depositing amorphous silicon alloyin a continuous roll-to-roll process. The solar cells created from this process are calledAmorphous Silicon Solar Cells, or A-Si. Solar Panels constructed using amorphoussilicon technology is more durable, efficient, and thinner than their crystallinecounterparts.

For very important solar projects, such as space probes that have to rely on solarenergy, very-high efficiency solar cells are constructed from gallium arsenide by aprocess called molecular beam epitaxial. Solar cells constructed by this process haveseveral p-n junction diodes, each designed to be maximally efficient at absorbing agiven part of the solar spectrum. These solar panels are much more efficient thanconventional types, but the process and materials involved make them far too

expensive for everyday applications.

The newest solar panels function on the molecular or quantum level, and represent anexciting new technology coming into play. These solar panels are created by implantingcarbon nanotubes or quantum dots into a treated plastic. Unlike silicon-based solarpanels, these solar panels do not have to be constructed in a clean room, and thereforeproduction costs are somewhat demised.


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The amount of power solar panels produce is influenced by the quality of the solarpanel, the materials and technology used in making the solar panel, and the amount oftime the solar panel has been in use. When purchasing solar panels, it is therefore wiseto look beyond size and look at the dollars/watt ratio.

04.4 Process of making a solar panel

Making solar panels is a delicate process, and it is for this reason that major solaradvances did not come into play until the lattermost quarter of the last century, whenadvances in semiconductors and photovoltaic design allowed increasingly efficient andaffordable solar cells to be developed.

Crystalline Silicon Solar Panels

The creation of solar panels typically involves cutting crystalline silicon into tiny disksless than a centimeter thick. These thin, wafer-like disks are then carefully polished andtreated to repair and gloss any damage from the slicing process. After polishing,dopants (materials added to alter an electrical charge in a semiconductor orphotovoltaic solar cell) and metal conductors are spread across each disk. Theconductors are aligned in a thin, grid-like matrix on the top of the solar panel, and arespread in a flat, thin sheet on the side facing the earth.

To protect the solar panels after processing, a thin layer of cover glass is then bonded tothe top of the photovoltaic cell. After the bonding of protective glass, the nearly-

finished panel is attached to a substrate by expensive, thermally conductive cement.The thermally conductive property of the cement keep the solar panel from becomingoverheated; any leftover energy that the solar panel is unable to convert to electricitywould otherwise overheat the unit and reduce the efficiency of the solar cells.

Despite these protective measures against the tendency of solar panels to overheat, it isvital that when installing a solar panel, additional steps should be taken to ensure thesolar panel is kept cool. Elevating the solar panel above ground (see solar panelmounts) to let the airflow underneath cool the device.

Amorphous Silicon Solar Panels

Amorphous silicon solar panels are a powerful, emerging line of photovoltaic, thatdiffers in output, structure, and manufacture than traditional photovoltaic which usecrystalline silicon. Amorphous silicon solar cells, or A-si cells, are developed in acontinuous roll-to-roll process by vapor-depositing silicon alloys in multiple layers,with each extremely thin layer specializing in the absorption of different parts of the


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solar spectrum. The result is record-breaking efficiency and reduced materials cost (A-sisolar cells are typically thinner than their crystalline counterparts).

Some Amorphous Solar Panels also come with shade-resistant technology or multiplecircuits within the cells, so that if an entire row of cells is subject to complete shading,

the circuit won't be completely broken and some output can still be gained. This isespecially useful when installing solar panels on a boat.

The development process of Amorphous Silicon solar panels also renders them muchless susceptible to breakage during transport or installation. This can help reduce therisk of damaging your significant investment in a photovoltaic system.

04.5 Solar Panel Installation

Solar Panels are typically installed on rooftops, building tops, or stand-alone facilities. Itis vital to install the solar panel so that it gets the most direct sun exposure - solar panelis maximally effective year round. To do this, there are several web-based solarresources to help properly set up and install the solar panels by tracking the position ofthe sun in the sky over the course of the year.

Position the solar panel in direct sunlight

Solar Panels perform at optimum capacity when placed in direct sunlight. Try toposition the photovoltaic array directly under the noontime sun for maximum

efficiency from the photovoltaic unit.

Notice obstructions to sunlight

Remove all items unnecessary items or trim branches that may be blocking sunlight toyour solar unit. Trace the path of the sun in the sky to determine if an object is casting ashadow over the solar photovoltaic panels. If this is the case, then the operatingefficiency of the unit will undoubtedly suffer.

Mounting the solar Panel

Solar Panel Mounts are used to install photovoltaic solar panels. Solar panel mountscome in three main varieties: pole mounts, roof-ground mounts, and flush mounts.Using these mounts, one can install the solar panel onto an RV, on top of or against theside of a pole, on the roof, or even install them as a free-standing unit.


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Water pumping with solar panels

A good way to put solar panels to use is to install a solar-powered water pump for well.Although windmills have traditionally been used to power such systems, a solar-powered system works just as well, and is equally friendly to the environment.

Well Pump

It is important to choose a quality well pump for use with the solar powered well pumpsystem, one that makes the best use of the power and doesn't require an inefficient,wasteful transformer. Well drilling provider is likely to offer the industry standard wellpump, a 220 volt alternating current model. The problem with such a high-voltagepump system is that the required transformer is extremely wasteful and can be a hugestrain on the inverter during startup. This can cause the power to home to dip, and thelights to dim, which can cause a full-out inverter failure unless one has a top-qualityinverter. Avoid such a high voltage system if one can, and instead, opt for a 120 volt AC

model, which is much more efficient and does not put nearly as much of a burden onthe inverter.

04.6 Home Solar Panel Efficiency [13]

Use of solar panels at household level has increased largely today. Solar panels are usedin cooking, heating, boiling and a large number of electric appliances. Solar panels areinstalled to generate solar energy for microwaves, refrigerator, electric gas, iron, waterheater, air conditioner, inverter, room heater and many other devices at home. Solar

energy is abundant, renewable and cheap.

While calculating the solar panel efficiency at home, we must first make an averageestimate of the total energy consumed by these electrical devices and then calculate thesolar panel efficiency. Scientists have found out that of the total solar energy striking thesolar panels; only 20% is converted to electrical energy. That means home solar panelefficiency is average 20%, when the solar energy is converted to electricity. When itcomes to lighting bulbs or tube lights, then the efficiency further falls. For example, ifthe solar cell efficiency is 20 %, the rest part goes in converting the direct current toalternating current which consumes 15 % more energy. The energy that is left is finallyused to light bulbs and the output is only 5% efficiency. Due to the low output, solarpanels are normally not used to light up homes. This was an approximate estimation ofsolar panel efficiency at home.


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Fig 17: Solar home system

04.7 Flexible Solar Panel Efficiency [13]

Flexible solar panels are used for devices which require low solar panel output andgenerate less energy. The flexible solar panel devices are solar hot water heaters, solar

landscape lights like solar garden lights, solar security lights, solar sunlights and solarflood lights solar fountains and pumps, solar battery chargers, photovoltaic solar celletc. These flexible devices also require a low consumption of solar energy, and thereforea low efficiency solar panel can be used. The output should be between 5% to 20%.

04.8 Precautions of Solar Panel

If the solar panel cover is not hermetically sealed like insulated window glass,then one may be able to replace it with a new piece. Be sure to use tempered

glass to protect the cells from hail and flying objects. Seal the new glass so it iswater tight.Broken panels produce low power, but one won't know how low without testing.If several panels are connected together with the broken one, the voltage of theentire string will degrade to whatever output the broken panel is producing.Be careful with damage in newer crystalline panels. Even one broken cell willreduce the power of the module by 25 to 33%.

Chapter 4- Solar Panel

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