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Wednesday, July 15, 2015

What Are Solar Panels?




The sun is the primary source of energy on Earth and sunlight can be converted directly into electricity using solar panels. Electricity has become indispensable in life. It powers the machines that most us use daily.
So, what are solar panels? What if you can create your own?
In this article, we will show you a straightforward method of building your own functional solar panel.
THE COMPONENTS
A solar panel is usually manufactured from six (6) components namely the PV (photovoltaic) cell or solar cell which generates the electricity, the glass which covers and protects the solar cells, the frame which provides rigidity, the backsheet where the solar cells are laid, the junction box where the wirings are enclosed and connected, and the encapsulant which serves as adhesives.
Since most people does not have access to equipment in manufacturing solar panels, it is important to note and understand those six components in order for anyone to be able to plan the materials needed to create a do-it-yourself or home-made solar panel.
The materials needed on how to make a solar panel must be available for purchase locally or online and should not exceed the cost of a brand new solar panel or does not take a long time to build.
1.) PV Cell
The first thing to consider when building your own solar panel is the solar cell.
Photovoltaic (PV) cell or solar cell converts visible light into electricity. One (1) solar cell however is not enough to produce a usable amount of electricity much like the microbot in Baymax (Hero 6) which only becomes useful when combined as a group. This basic unit generates a DC (direct current) voltage of 0.5 to 1 volt and although this is reasonable, the voltage is still too small for most applications. To produce a useful DC voltage, the solar cells are connected in series and then encapsulated in modules making the solar panel. If one cell generates 0.5 volt and is connected to another cell in series, those two cells should then be able to produce 1 volt and they can then be called a module. A typical module usually consists of 28 to 36 cells in series. A 28-cell module should be able to produce roughly 14 volts (28 x 0.5 = 14VDC) which is enough to charge a 12V battery or power 12V devices.
Connecting two or more solar cells require that you have a basic understanding of series and parallel connection which is similar to connecting batteries to make up a battery storage system.
There are two most common solar cells that can be bought in the market; a monocrystalline cell and a polycrystalline cell. These two can have the same size, 156mm x 156mm, but the main difference would be efficiency. It is important to purchase additional cells to serve as backup in case you fail on some of the cells i.e. bad solder, broken cell, scratched, etc.
Monocrystalline solar cells are usually black and octagonal in shape. This type of solar cell is made of the highest and purest grade silicon which makes them expensive. But they are the most efficient of all types of solar cells and are almost always the choice of solar contractors when space is an important factor to consider in achieving the power they want to attain based on their solar system design.
Polycrystalline PV Cells are characterized by their bluish color and rectangular shape. These cells are manufactured in a much simpler process which lowers the purity of the silicon content and also lowers the efficiency of the end product.
Generally, monocrystalline cells are more efficient than polycrystalline cells but this does not mean that monocrystalline cells perform and outputs more power than polycrystalline cells. Solar cell efficiency has something to do with the size of the cells and every solar panel or cells have an efficiency rating based on standard tests when they were manufactured. This rating is usually in percentage and the common values range from 15% to 20%.
2.) Glass
The glass protects the PV cells while allowing optimal sunlight to pass through. These are usually made of anti-reflective materials. Tempered glass is the choice of material nowadays even for unknown and new manufacturers although there are still those who utilize flat plate glass on their solar panels. Tempered glass are created by chemical or thermal means and is many times stronger than plate glass making it more expensive to produce but the price of manufacturing them today is reasonable and cost-effective. Flat plate glass creates sharp and long shards when broken as opposed to tempered glass which shatters safely in small pieces upon impact, that is why they also call it safety glass. It should be noted here that most amorphous solar panels uses flat plate glass because of the way the panel is constructed.
Tempered glass is what manufacturers use in mass producing their solar panels. In our DIY project, we suggest to use Plexiglas also called acrylic glass which is safer than the regular normal glass from your local hardware store. It is a bit expensive than regular glass but is weather resistant and does not break easily. The Plexiglas can also be screwed or glued easily to the frame.
3.) Frame
A frame is usually made of anodized aluminum which provides structure and rigidity to the solar module. These aluminum frames are also designed to be compatible with most solar mounting systems and grounding equipment for easy and safe installation on a roof or on the ground.
The frame in a factory-built solar panel is usually the aluminum part where all four sides of the solar panel sheet are inserted. Think of it as a skeletal rectangular frame. The solar panel sheet by the way is composed of the other 4 components and are layered and laminated in the following order from top to bottom; the tempered glass, top encapsulant, the solar cells, bottom encapsulant, then the backsheet. In our DIY solar panel, we will be using a wooden frame and the end-result would be something analogous to a picture frame where the picture is the solar cells glued to a non-conductive board, the glass for the Plexiglas top cover, and the wooden part as the frame and backsheet.
4.) Backsheet
The backsheet is the layer of plastic film on the back surface of the module. This is the only layer protecting the module from unsafe DC voltage. The main function of the backsheet is to insulate and protect the handler from shock and provide the safest, efficient, and dependable electrical conductivity possible.
The backsheet will be a wooden plywood where the frame will be screwed on top and on the sides. It should be noted here that a perforated hardboard (Pegboard) will be used to place and align the PV Cells and this Pegboard will sit on top of the wooden backsheet and fitted inside the wooden frame.
5.) Junction Box
The junction box is where the terminal wires and bypass diodes are located and concealed. The terminal wires are basically the positive and negative wires based on the series connections of the PV Cells and can be connected to another solar panel, a charge controller, a battery system, or to an inverter, depending on the system design. The bypass diode is a protective mechanism that prevent power from getting back to the solar panel when it is not producing electricity as in the case when it is night time.
There are junction boxes designed for factory-built solar panels that are now available to purchase online especially from China. If you are not pressed for time, you can order online and wait for the delivery otherwise you can just purchase a regular electrical junction box from your local hardware store. The purpose of the junction box is to protect the terminals (positive and negative terminals) from water, dust, and other elements. This is also where the two wires (red for positive and black for negative) will be coming from. The other end of these two wires can also be protected by using a PV accessory called MC4 which can also be purchased online together with the PV junction box.
6.) Encapsulant
Encapsulant sheets prevent water and dirt from infiltrating the solar modules and serve as shock-absorbers that protect the PV cells. They have this adhesive bonding capability to the glass, the PV cells, and the backsheet similar to a glue but stronger. Encapsulants are usually made of Ethylene-Vinyl Acetate or EVA and are applied using lamination machines and processes. Solar panel manufacturers use a vacuum and a large oven to properly seal and cure the EVA sheet onto the solar panels. Most of us do not have the capability to do this but many still have tried and failed while others had varying levels of success.
Encapsulants are thin plastic sheets that are usually laminated on the top and bottom parts of the solar cell sheet. The bottom encapsulant is the layer on top of the backsheet where the solar cells are actually placed and supported. In our project, we will instead use a latex acrylic paint. This paint will not be applied to the pv cells because when attempted, will not result in an equal distribution or application of the liquid to the surface of the cells which can degrade performance. The paint will be applied to the wooden frame, wooden backsheet, and to the Pegboard. This Latex Acrylic paint should be able to protect the wooden parts from UV rays and can better resist blistering and cracking overtime. This paint, although water-soluble, can dry quickly and becomes water-resistant.
At http://howtomakeasolarpanel.net, we write articles specifically focused on solar panels meant for the home and other personal uses. We provide our guests with direct links to purchase books and programs on any solar panel topic.
Come check out our page of educational YouTube videos for the DIY folks. Anything to do with solar and the efficiency of cells and panels is discussed on our blog.

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