DIY Solar Cells - Testing And Productivity

Solar Cell Productivity

Regardless of how large solar cells are they produce around 0.5 volts .

But keep in mind that size does affect the current output of the cell.A solar cell with a bigger surface will produce more electrical current than one with a smaller surface.

You need to be aware of this when designing your solar panel for specific purposes.

If a large amperage is needed,you must go for solar cells with a high current output,or large ones.

Low current solar cells can be enough for low power needs.

Currently large surface solar cells are the most used,but keep in mind that the more current a cell produces,the higher the cost will be.

You also need to be aware of your surrounding climate when choosing between cell output.High current solar cells can charge batteries faster in less than ideal weather conditions,such as cloudy areas,during the winter when sunlight is very scarce daily.High current solar cells are also recommended when the drain on your batteries will be high and batteries will require a speedy and frequent recharge.

Solar Cell Watt Ratings

Just about all solar cells have a current rating as well as voltage rating provided,or short circuit and open circuit current rankings.To recognize the watt rating in the cell we have to multiply the current by the voltage,when you've got a cell with a 4 amp current and 0.5 voltage,that cell is graded as being a 2 watt cell.

Presently solar cells can range from milliamps up to the 6 amp output,but for a efficient task a 1-4 amp cell is sufficient.

Solar Cells involving 2 and 3 amps are often the most frequent and also available at great costs.

Testing Solar Cells

Solar Cell producers examine their solar cells in Air Mass conditions,or AM1 .

Air Mass determines the amount of air light photons need to travel just before they get to the earth on the ocean level.

Air Mass 1 comes about when sunlight is directly overhead at sea level as well as the energy it provides towards the solar cell is approximately 1 KW per square meter. 

How To Test Your Solar Cells

Each and every cell in your diy solar panel needs to be tested,if you have OF-SPEC solar cells then you need to group them in categories from low to high outputs.

If you make the mistake to include a low output solar cell into a high output solar panel,that cell will take down all the other cells to its level,and thus rob them of energy.

To examine your cells you need a very clear day,the best time being in the summer in the maximum point in the solstice when the weather is the nearest to AM1.

Alternatively you can test solar cells at any time during the day,but keep in mind that they will not show their full potential.

Difference between monocrystalline polycrystalline and Amorphous thin film solar cell?

5″ monocrystalline Silicon 5 inch 125 Series Solar Cell 6″ Polycrystalline Silicon 6 inch 156 Series Solar Cell

1. Difference between crystal and amorphous? Daily to see the solid is divided into two major categories of non-crystalline and crystalline, non-crystalline arrangement of atoms within the material is not necessarily the law of the fracture when the fracture is random, such as plastic and glass, and called the crystal material, represent the natural shape of a regular polyhedron, with obvious edges and corners with the plane, the atom is in accordance with its internal law must line up neatly, so when they break off the plane according to certain, such as salt, crystal and so on.

2. Difference between single crystal and polycrystalline? Some of the crystal is composed of many small grains, if the arrangement between the grains are no rules, this is called polycrystalline crystal, such as copper and iron. But there are also the crystal itself is a complete large grains, the crystal is called single crystal, crystal and crystal diamond.

3. Monocrystalline silicon and polycrystalline silicon photovoltaic cells compare? Monocrystalline silicon cells with a cell conversion efficiency, good stability, but the cost is high. Low-cost polycrystalline silicon cells, the conversion efficiency slightly lower than the Czochralski silicon solar cells and materials in a variety of defects such as grain boundaries, dislocations, micro-defects, and material impurities carbon and oxygen, as well as the stained process transition metals.

The first is the advent of solar cell silicon solar cells. Silicon is very abundant on the earth, an element almost everywhere have the presence of silicon can be said to be used without silicon to make solar cells, indeed no shortage of raw materials. But it is not easy to extract, so people in the production of monocrystalline silicon solar cells, they also studied the polycrystalline silicon solar cells and amorphous silicon solar cells, has commercial-scale production of solar cells, also did not jump out of silicon series. In fact, the semiconductor materials for manufacture of solar cells a lot, along with the development of industrial materials, solar cells will be more and more varieties. Research and trial production has been the solar cell, in addition to silicon series, there are cadmium sulfide, gallium arsenide, copper indium selenium and many other types of solar cells, too numerous to mention, the following are a few of the more common solar cells.

Monocrystalline silicon solar cells

Monocrystalline silicon solar cells is currently the fastest developing a solar cell, its composition and production technology has been finalized, the products have been widely used for space and ground facilities. The high purity single crystal silicon solar cells as the raw material rod, 99.999% purity. In order to reduce production costs, and now solar terrestrial applications such as the use of solar-grade silicon rods, material performance has been relaxed. Some semiconductor devices can also be used for processing materials and discard ends of silicon materials, solar cells made by re-drawing a dedicated silicon rods. The slice of silicon rods, generally 0.3 mm thick slices. Wafer after forming, polishing, cleaning and other processes, made of silicon raw material to be processed. Solar cell processing chip, the first doping and diffusion in silicon, usually for the small amount of boron dopant, phosphorus, antimony and so on. Diffusion is the control into the quartz furnace for high temperature diffusion. And then using screen printing will be printed with a good paste made of silicon gate line, after sintering, also made of the back electrode and a gate line in the face of anti-reflection coating source, to prevent a large number of photons reflected from a smooth silicon surface, thus, single-chip silicon solar cells are produced. After single-chip random testing, according to the required specifications can be assembled into solar modules (solar panels), the method used in series and parallel to a certain output voltage and current, and finally with the framework and package materials package. According to the system user can design different size solar module solar cell composed of a variety of square, also known as the solar array. Current silicon photoelectric conversion efficiency of solar cells is about 15%, laboratory results have more than 20%. Also for the space station up to 50% or more solar panels.

Polycrystalline silicon solar cells

Monocrystalline silicon solar cell production requires large amounts of high-purity silicon material, the production of these materials, process complexity, power consumption drastically, the total cost of solar cell production has been over half, combined with the silicon rod was drawn cylindrical, sliced wafer production solar cells is to form a solar module surface low utilization rate. Thus, 80 years, some European and American countries, the development into a polycrystalline silicon solar cells. Polycrystalline silicon solar cells using current materials, mostly a collection contains a lot of single crystal particles, or silicon materials from waste materials and metallurgical grade silicon melt molded. The process is to select a resistivity of 100 to 300 ohms? Cm block of material or a polycrystalline silicon material end to end, after crushing, with the 1:5 mixture of hydrofluoric acid and nitric acid corrosion appropriate, and then spent neutral-ionized water rinse and drying. Quartz crucible installed polysilicon materials, the addition of appropriate amount of boron in silicon, release the casting furnace, heating and melting in a vacuum state. Melted insulation should be about 20 minutes, and then injected into the graphite mold, to be cooled slowly solidified, that have polysilicon ingot. The ingots can be cast cubes to be processed into square slices film solar cells can improve material utilization and easy assembly. Polycrystalline silicon solar cells and solar cell production process is similar to the photoelectric conversion efficiency of about 12%, slightly lower than the silicon solar cells, but the material is simple, to save power consumption, the total production costs low, so get a lot of development. As the technology was improved, the current conversion efficiency of polycrystalline silicon can also be reached around 14%.

Amorphous silicon solar cells

Amorphous silicon solar cells appeared in 1976 with a new thin film solar cells, monocrystalline and polycrystalline silicon solar cells it with the production method is completely different, very little silicon material consumption, lower power consumption, very attractive. Method of manufacturing a variety of amorphous silicon solar cells, the most common is the glow discharge method, as well as reactive sputtering, chemical vapor deposition, electron beam evaporation and thermal decomposition of silane method. Glow discharge method is a Dan Yingrong device pumped into vacuum, hydrogen or argon gas filled diluted silane, with the RF power heating, ionization of silane to form a plasma. Deposition of amorphous silicon film on the substrate being heated. If the silane were mixed in the amount of hydrogenated or hydrogenated boron phosphate can be N-or P-type amorphous silicon film. Substrate materials are generally made of glass or stainless steel. Preparation of amorphous silicon thin film technology which depends mainly on the strict control of pressure, flow rate and RF power, the temperature of the substrate is also very important. The structure of amorphous silicon solar cells there are different, which has a structure called the PiN better battery, it is first deposited on the substrate N-type layer of amorphous silicon doped with phosphorus, and then deposited a layer of undoped i layer, and then deposited a layer of P-type boron-doped amorphous silicon, and finally a layer of electron beam evaporation of antireflection coatings, and deposition of silver electrodes. This production process, a series of deposition chamber can be used in production form a continuous process to achieve mass production. Meanwhile, the thin amorphous silicon solar cells can be made into laminated type, or use to manufacture integrated circuits in a plane, with the appropriate mask technology, a production of multiple batteries in series to obtain higher voltage . Because the average crystalline silicon solar cells around a single voltage of 0.5 volts, and now the production of amorphous silicon tandem solar cells in Japan up to 2.4 volts. The current problem is that of amorphous silicon solar cell conversion efficiency is low, the international advanced level of about 10%, and is not stable enough, often decline down conversion efficiency of the phenomenon, so not a lot of use for large-scale solar power, but mostly with in low light power, such as pocket electronic calculators, electronic watches and clocks and copier and so on. Failure to overcome the drop in efficiency issues, the amorphous silicon solar cells will promote the great development of solar energy, because its low cost, light weight, easier application, it can be combined with the housing of the roof form independent power of households.

In the fierce sun, single crystal solar panels can be transformed more and more non-crystal-type solar energy to electricity more than doubled, but unfortunately, the price of single crystal type of non-crystal-like than the two or three times more expensive, and in the case of non-cloudy Instead, the crystal-type transistor can be almost as much to collect solar energy.

Solar cell

As the world's oil resources dwindle by the minute, countries are scrambling to develop technologies that would power up in the future without oil. One of the most promising in this field is the utilization of solar cell energy. At present, some countries have already taken big steps to develop and make use of this technology. It had already been powering up buildings and some homes.

Making your own solar and wind power for less than $200

To capture the massive solar energy that is all around us, there is for developing better solar cells that would better utilize the exploitation of this natural resource. But how do these solar cells is made?

Most of the solar cells that are being sold are made of polysilicon. These are the cells use in small solar panels being installed on homes or in solar-powered calculators. These cells are usually placed as a group because even though a single cell can produce some power but for much higher energy needs, a group of cells would be much more efficient.

The manufacturing of solar cell energy begins in the preparation of silicon. The most commonly used is silicon oxide. It would first be subjected to high heat in a furnace which purifies it by 99 percent. It would still be purified until it reaches a purity of 99.5% which would make it ready to be made into cells.

Next would involve the crystallization of the purified silicon. The silicon would be melted and boron would be added to it. The boron would help generate the electrical basis of the silicon. These solar cells are now called the p-type or positively charged cells. The cells are still in what they call as ingots. They would still need to be cut very precisely (around 200-300 microns) by a computer guided cutter before the cells can be ready for the next step.

Making your own solar and wind power for less than $200

The next step would involve the immersion of the cells in a negatively charged chemical with water. Then, an anti-reflective layer would be added to make the cells absorb not reflect the sun's energy. This is what makes the solar cells look dark in the panels which are usually black or dark blue. Then, aluminum and silver conductors would be added so that the electricity produced by the cells can be transferred and stored to a battery.

Finally, the cells would be placed on a panel. The usual appearance would be in rows or columns although there are quite few that takes in different shapes. To protect it from damage because they are very fragile, a transparent glass or plastic would be placed over the cells. Frames would be added to keep the cells intact and for added protection as well. Now, the solar panel is now ready to be installed.

Before, the main problem of scientists is that solar cells are not efficient enough to produce electricity that could power even a single household. That is why it had been neglected for use as power source in the past. But now, solar cells have improved efficiency and its cost is staring to get cheaper than before. As science advances its study on solar cells, we are well on our way in fully solar cell energy to power our homes as well as the future of our planet.

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solar cells

A solar cell is a device which changes sunlight into electricity. A more technical term for a solar cell is a photovoltaic cell.

The term "photo" derives from the Greek word for "light," and the term "voltaic" comes from the word "volt" which means "electrical force." A "cell" is a small receptacle or container containing electrodes which generate power.

Thus, a photovoltaic cell is a container that creates electric force, through light.

Whereas a solar cell can generate electricity from any light source, its intended use is the collection of solar energy from the sun.

How a Solar Cell Works

The solar cell works as follows:

Photons (which are particles of light in sun rays) hit the surface of the solar cell and are absorbed a semiconductor, such as silicon.

These photons (bits of sunlight) knock electrons loose from the atoms inside the semiconductor. The photons then push the electrons along, leaving a "gap" in the atom. Another electron is then pulled from an adjacent atom to fill the gap. And so an electrical flow is generated.

The simplicity of this is that one atom has an extra electron, and the other atom is missing one. This is referred to as a "difference in potential." Nature, wanting to remain balanced, tries to even things out by pulling another electron from the neighboring atom.

A solar panel is comprised of a group of solar cells which are linked together to produce the desired amount of electrical energy.

A group of solar cells linked together can also be referred to as a "module." Thus the terms "solar panel," and "solar module," are synonymous to each other, and essentially mean the exact same thing. "Solar panel" is the more common term, and "solar module" is the technical term.

One can use solar panels individually or one can link several together in order to generate more electricity. When a group of solar panels are linked together, it is called a "solar array". The more solar panels are included in a solar array, the more power they produce.

Solar Power is a clean and virtually unlimited source of energy. I say "virtually unlimited" because the sun itself won't last forever. But we won't have to worry about that for the next few billion years.

Since solar power is a clean energy source which has been around for decades, one might wonder why its not used more. The answer to this lies partially in the cost of producing solar panels, as well as in the efficiency of the solar panels.

We are currently in the second generation of solar panel technology and verging on the third. A lot has changed since the first generation. Solar panels a are becoming a viable source of clean energy.

The solar cells of earlier times were relatively large and bulky compared to our current models. In view of the amount of energy and material required to produce them, and the amount of energy they actually produced, it was more costly to use solar energy than to use fossil fuels. The only exception was in places where little or no fossil fuels were available, such as in space.

With the second-generation solar cells, we attempted to tackle this exact problem. We attempted improve manufacturing techniques so as to reduce the costs, materials and energy needed for the production of solar cells.

Recently, major advances have been made in the production of solar cells, which have reduced production costs.

One contribution in this area was the development of techniques to coat glass or ceramic materials with very thin layers of semi-conductive substances. This made it possible to produce solar panels using only a fraction of the semi-conductive material that was required earlier. The production of solar panels using this second-generation technology is referred to as "Thin Film Technology."

Third-generation solar energy technologies are currently being researched and developed. The objective is to improve the power of solar cells even further (while keeping production costs to a minimum) in which case thirty to sixty percent of the sunlight hitting the panels will be converted into electricity. (Currently, solar panels convert only about twenty percent.)

But regardless of third generation solar technology, the second-generation solar cell is efficient enough to make solar technology viable - and a host of new solar-powered products have hit the consumer market.

Solar-powered calculators have been in use for a while now, we've all seen them. We have even seen a few other novelty devices. But only in the last few years have solar devices come into serious and practical use.

The last two years in particular have seen a virtual explosion of solar devices hitting the market. Solar flashlights (I've often wandered what use they were), solar-powered radios, and, recently, solar battery chargers.

One can also now find a wide range of portable solar chargers and panels, which are lightweight and easy to transport, yet capable of providing a decent amount of power in even the most remote locations. Solar chargers are becoming a standard part of wilderness survival kits and emergency preparedness kits.

All of this is a result of the developments in solar cell technology, and the coming of the Solar Age.

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The classification of solar cells

Crystalline solar cell according to the state Department of membrane can be divided into crystalline and amorphous thin film system (hereinafter expressed as a-) two categories, while the former is further divided into single-crystalline and multi-crystalline.

Silicon thin film can be divided according to material type, shape and compound semiconductor thin film of organic film-shaped, and compound semiconductor thin film is divided into non-crystalline form (a-Si: H, a-Si: H: F, a-SixGel-x: H, etc.), Ⅲ V family (GaAs, InP, etc.), Ⅱ Ⅵ group (Cds lines) and zinc phosphide (Zn 3 p 2) and so on.

Materials used in solar cells based on different solar cell can be divided into: silicon solar cells, multi-compound thin film solar cells, polymer solar cells modified electrode layers, nano-crystalline solar cells, organic solar cells, silicon solar cells which is the development of the most mature, dominant in the application.

(1) silicon solar cells

Monocrystalline silicon solar cells into solar cells, polycrystalline silicon thin film solar cells and amorphous silicon thin film solar cells of three. The highest conversion efficiency of silicon solar cells, the most mature technology. In the laboratory the highest conversion efficiency of 24.7%, the scale of production efficiency is 15%. In large-scale applications and industrial production is still dominant, but because of the high cost price of silicon, significantly reducing its cost is difficult, in order to save silicon material, the development of polycrystalline silicon as the silicon film and amorphous silicon thin film solar battery replacements.

Polycrystalline silicon thin film solar cells with relatively low cost, and more efficient than amorphous silicon thin film battery, the maximum conversion efficiency of its laboratory was 18%, the conversion efficiency of industrial-scale production of 10%. Therefore, the polycrystalline silicon thin-film batteries will soon be the international space station solar panel In the solar power to dominate the market.

Low cost amorphous silicon thin film solar cells, light weight, high efficiency, ease of mass production, there is great potential. However, the material is subject to the efficiency of recession caused by the photoelectric effect, the stability is not high, a direct impact on its practical application. If we can solve the stability problems and further improve the conversion rate problem, then, amorphous silicon solar cells is undoubtedly a major development of solar products.

(2) Multiple compound thin film solar cells

Multiple compounds as inorganic thin film solar cell materials, which include III-V compound gallium arsenide, cadmium sulfide, cadmium sulfide and copper indium selenide thin film batteries. CdS, CdTe polycrystalline thin film cell efficiency than amorphous silicon thin film solar cell efficiency, lower costs than single crystal silicon cells, and also easy to mass production, but cadmium is highly toxic, causing serious on the environment pollution, therefore, is not the best crystalline silicon solar cell replacement. Gallium arsenide (GaAs) III-V compounds, the conversion efficiency of the battery up to 28%, GaAs compound materials have very good optical band gap and higher absorption efficiency, anti-radiation ability, is not sensitive to heat, suitable for manufacturing efficient single-junction cells. But the expensive GaAs material, which largely limited the popularity of using GaAs cells.

Copper indium selenide thin film battery (CIS) for photoelectric conversion, there is no light-induced recession, the same conversion efficiency and polysilicon. Has low price, good performance and simple process, etc., will be the future development of solar cells is an important direction. The only problem is the source material, the indium and selenium are relatively rare element, therefore, the development of such batteries and will be subject to restrictions.

(3) multi-layer polymer solar cells modified electrode

Organic polymers instead of inorganic materials is just the beginning of a solar cell manufacturing research. As the organic material flexible, and make easy, extensive source material, the cost advantages of the end to large-scale use of solar energy is important to provide cheap electricity. However, organic materials, solar cells prepared just the beginning, whether life or efficiency of the battery can and inorganic materials, especially compared to silicon cells. Can develop into a practical significance of products, but also needs further study and explore.

(4) nano-crystalline solar cells

Nano-crystalline TiO2 solar cells chemical energy is a newly developed, is that it costs cheap and simple process and a stable performance. The optical efficiency of 10% or more stable, production cost of silicon solar cells is only 1 / 5 ~ 1 / 10. Life can reach more than 20 years.

Research and development of such batteries just started in the near future will gradually onto the market.

(5) Organic solar cells

Organic solar cells, organic materials that constitute the core part of the solar cells. We are not familiar with organic solar cells, which is reasonable in the matter. Now in mass production of solar cells, more than 95% of silicon, while the remaining less than 5% is made by other inorganic materials.

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what is photovoltaic?

Photovoltaics (abbreviated PV) is the most direct way to convert solar radiation into electricity and is based on the photovoltaic effect, which was first observed by Henri Becquerel [1] in 1839. It is quite generally defined as the emergence of an electric voltage between two electrodes attached to a solid or liquid system upon shining light onto this system. Practically all photovoltaic devices incorporate a pn junction in a semiconductor across which the photovoltage is developed. These devices are also known as solar cells. Light absorption occurs in a semiconductor material. The semiconductor material has to be able to absorb a large part of the solar spectrum. Dependent on the absorption properties of the material, the light is absorbed in a region more or less close to the surface. When light quanta are absorbed, electron hole pairs are generated, and if their recombination is prevented they can reach the junction where they are separated by an electric field. Even for a weakly absorbing semiconductor like silicon, most carriers are generated near the surface. This leads to the typical solar cell structure of Fig. 1.1.

The pn junction that separates the emitter and base layer is very close to the surface in order to have a high collection probability for the photogenerated charge carriers. The thin emitter layer above the junction has a
relatively high resistance which requires a well designed contact grid, also shown in the figure.
For practical use solar cells are packaged into modules containing either a number of crystalline Si cells connected in series or a layer of thin-film material which is also internally series connected. The module serves two purposes: It protects the solar cells from the ambient and it delivers a higher voltage than a single cell, which develops only a voltage of less than 1Volt. The conversion efficiencies of today’s production cells are in the range of 13 to 16%, but module efficiencies are somewhat lower. The best laboratory efficiency of crystalline silicon achieved so far is 24.7%, which approaches the theoretical limit of this type of solar cell.
As we shall see in Chap. 5, pn junctions and semiconductors are not the only way to achieve photovoltaic conversion. The future may hold many new materials and concepts. (A. Goetzberger, V.U. Hoffmann 2005)