Solar energy is just great, but here's the problem: even one battery costs a lot of money, and for a good effect you need more than one, and not even two. That's why the idea comes up - to collect everything yourself. If you have a little soldering skill, it's easy to do. The whole assembly consists in connecting the elements in series in tracks, and fixing the tracks on the body. Let's talk about the price right away. A set for one panel (36 pieces) costs around $ 70-80. And completely with all materials, solar panels with their own hands will cost you about $ 120-150. Much less than the factory ones. But I must say that they will also be less in terms of power. On average, each photoconverter produces 0.5 V, if 36 pieces are connected in series, it will be about 18 V.
A bit of theory: types of solar cells
The biggest problem is purchasing photovoltaic converters. These are the same silicon wafers that convert sunlight into electricity. This is where you need to understand a little about the types of photocells. They are produced in two types: polycrystalline and monocrystalline. Monocrystalline are more expensive, but have a higher efficiency - 20-25%, polycrystalline - cheaper, but their performance is lower - 17-20%. How to distinguish them externally? Polycrystalline have a bright blue color. Monocrystalline is slightly darker and they are not square, but multifaceted - a square with cut edges.
About the form of release. There are photocells for solar panels with conductors already soldered, and there are kits where the conductors are attached and everything needs to be soldered by yourself. Everyone decides what to buy, but it must be said that without skill you will damage at least one plate, but rather not one. And if you are not very good at soldering ... then it is better to pay a little more, but get the parts that are almost ready for use.
It is unrealistic to make solar cells for solar panels with your own hands. To do this, you need to be able to grow silicon crystals, and then still process it. Therefore, you need to know where to buy. More on that later.
Where and how to buy photocells
Now about the quality. On all Chinese sites like Ebay or Alibaba, rejection is sold. Those parts that have not passed the tests at the factory. Therefore, you will not get a perfect battery. But their price is not the highest, so you can put up with it. In any case, at first. Collect a couple of test solar cells with your own hands, fill your hand, and then you can take it from the factory.
Some sell solar cells sealed in wax. This prevents them from spoiling during transportation, but getting rid of the wax and not damaging the plates is quite difficult. You need to dip them all together in hot, but not boiling water. Wait until the wax melts, then carefully separate. Then, one by one, bathe each plate in hot soapy water, then dipping it into clean hot water. You will need several such "ablutions", water and soap solution will have to be changed, and more than once. After the wax is removed, lay the clean plates on a terry towel to dry. This is a very troublesome business. So it's better to buy without wax. It's much easier that way.
Now about shopping on Chinese sites. Specifically about Ebay and Alibaba. They are verified, thousands of people buy something there every day. The system is no different. After registration, as usual, in the search bar, type the name of the element. Then choose the offer you like for some reason. Be sure to choose from those options where there is free shipping (in English free shipping). If there is no such mark, then delivery will have to be paid separately. And it is often more than the cost of the goods and certainly more than the difference that you get on the price.
You need to focus not only on the price, but also on the seller's rating and reviews. Carefully read the composition of the product, its parameters and reviews. You can communicate with the seller, only messages need to be written in English.
About payment. It is transferred to the seller on these sites only after you unsubscribe to receive the goods. In the meantime, delivery is in progress, your money is in the account of the trading platform. You can pay with a card. If you are afraid to shine the card data, use intermediate services. They are different, but the essence is the same - your card will not light up. There is also a return of goods on these sites, but this is a long song, so it is better to take from trusted sellers (with a good rating and reviews).
Yes. The package is depending on the region. And it's not so much how long it will take to leave China, but how soon the mail will deliver it. In the best case - three weeks, but maybe a month and a half.
How to assemble
DIY solar battery assembly consists of three stages:
- Frame fabrication.
- Soldering solar cells.
- Framing and sealing.
The frame can be made from aluminum corners or wooden slats. But the shape of the frame, materials, manufacturing sequence depend on the installation method.
Method one: installation on a window
The battery is hung on the window, on the frame from the inside of the room or outside, but also on the window. Then you need to make a frame from an aluminum corner, and glue glass or polycarbonate to it. In this case, at least small gaps remain between the photocells, through which a little light enters the room. The size of the frame is based on the size of your photocells and how you are going to position them. Also, the size of the window can play a role. Please note that the plane must be flat - photovoltaic converters are very fragile, and will crack at the slightest misalignment.
Unfold the finished frame with glued glass face down, apply a layer of sealant to the glass surface. On the sealant, again face down, lay the rulers assembled from the photocells.
From a thick elastic foam rubber (thickness not less than 4 cm) and a piece of plastic film (200 microns) make a mat: cover the foam rubber with a film and fasten it well. It is better to solder the polyethylene, but you can also use scotch tape, only all the joints should be on one side. The second should be flat and smooth. The size of the mat should fit well into the frame (without bends and efforts).
The mat was placed on the photocells embedded in the sealant. On it is a board, which is slightly smaller in size than the frame, and a solid load on the board. This simple device will help to expel air bubbles trapped under the photocells. Air decreases productivity, and it is very strong. Because the fewer bubbles there are, the better. Leave the entire structure for 12 hours.
Now is the time to remove the load and peel off the mat. Do it slowly and slowly. It is important not to damage the soldering and conductors. Therefore, pull smoothly, without jerking. After the mat has been removed, the panel must be left for a while - to dry out. When the sealant stops sticking, you can hang the panel and use.
Instead of a lengthy procedure with a sealant, you can take a special sealing film. It's called EVA. Just spread the film on top of the battery assembled and laid on the glass and heat it with a construction hairdryer until it is completely sealed. It takes several times less time.
Method two: installation on a wall, roof, etc.
In this case, everything is different. The back wall must be solid and non-conductive. Perhaps - wood, plywood, etc. Therefore, it makes sense to make the frame from wooden bars. Only the height of the body should be small so that the shadow from the sides does not interfere.
In the photo, the case consists of two halves, but this is not at all necessary. It's just easier to assemble and lay short rulers, but there will be more connections in this case. Yes. Several nuances: you need to provide several holes in the case. In the lower part, several pieces are needed for the condensate outlet, as well as two holes for the output of the conductors from the battery.
Then paint the battery casing with white paint - silicon wafers have a fairly wide operating temperature range, but it is not unlimited: from -40 o C to +50 o C. And in the summer, in a closed box, +50 o C runs easily. Therefore, white is needed so that the photoconverters do not overheat. Overheating, like hypothermia, reduces efficiency. This, by the way, can be an explanation for an incomprehensible phenomenon: noon, the sun is hot, and the battery began to give less electricity. And she's just overheated. For the southern regions, you probably need to stack the foil. It will be more efficient. Moreover, the productivity is likely to increase: radiation reflected by the foil will also be captured.
After the paint has dried, you can lay the collected paths. But this time, face up. How to fix them? A drop of heat-resistant sealant in the middle of each plate. Why not apply over the entire surface? Due to thermal expansion, the plate will change size. If you stick it only in the middle, nothing will happen to it. If there are at least two points, it will burst sooner or later. Therefore, gently apply a drop in the middle, gently press the plate. Don't press - crushing is very easy.
In some cases, the plates were first attached to the base - a sheet of fiberboard, painted in the same white color. And then, on the basis, they were fixed to the body with screws.
After all the rulers are laid, connect them in series. To prevent the conductors from dangling, they can be fixed with a few drops of sealant. You can remove the wires from the elements through the bottom or through the side - whichever is more convenient. Pull them through the hole, and then fill the hole with the same sealant. Now you need to let all the connections dry. If the lid is closed earlier, deposits will form on the glass and photocells, which will greatly reduce the efficiency of the battery. Therefore, we wait at least a day (or as much as indicated on the sealant packaging).
Now it's just a small matter - cover everything with glass or transparent plastic. How to fix it is up to you. But do not seal at first. At least until the test. Maybe there is a problem somewhere.
And one more nuance. If you plan to connect batteries to the system, you will need to install a diode that will prevent the battery from discharging through the battery at night or in bad weather. It is best to install a Schottky diode. I connect it to the battery in series. It is better to install it inside the structure - at high temperatures, its voltage drop decreases, i.e. in working condition, it will "sink" voltage less.
How to solder solar cells
A little about handling silicon wafers. They are very, very fragile, easy to crack and break. Therefore, you need to handle them with extreme caution, store them in a tight container away from children.
You need to work on a flat, solid surface. If the table is covered with oilcloth, place a sheet of something hard. The plate should not bend, but with its entire surface firmly rest on the base. Moreover, the base must be smooth. Experience has shown that the ideal option is a piece of laminate. He is hard, smooth, smooth. They are soldered on the back side, not on the front side.
For soldering, you can use flux or rosin, any of the compounds in the soldering marker. Here everyone has their own predilections. But it is desirable that the composition does not leave traces on the matrix.
Lay the silicon wafer face up (face - blue side). It has two or three tracks. They are coated with a flux or a marker, an alcoholic (not water-alcoholic) solution of rosin. Usually a thin contact tape is supplied with photoconverters. Sometimes it is cut into pieces, sometimes it goes on a reel. If the tape is wound on a spool, cut off a piece equal to twice the width of the solar cell, plus 1 cm.
Solder the cut piece onto the strip treated with flux. The tape turns out to be much longer than the plate, all the remainder remains on one side. Try to keep the soldering iron in place. As much as possible. For better soldering, you should have a drop of solder or tin at the tip of the tip. Then the soldering will be of high quality. There should be no unsoldered places, warm everything up well. But don't push! Especially around the edges. These are very fragile items. Solder tapes to all tracks one by one. Photoconverters are "tailed".
Now, in fact, about how to assemble a solar panel with your own hands. Let's start assembling the ruler. There are also tracks on the back of the record. Now we solder the "tail" from the upper plate to the lower one. The technology is the same: we coat the track with flux, then we solder it. So we connect the required number of photovoltaic converters in series.
In some versions, on the back side, not tracks, but platforms. Then there is less soldering, but there may be more quality claims. In this case, we coat only the sites with flux. And we also solder only on them. That's all, actually. The assembled tracks can be transferred to the base or cabinet. But there are many more tricks.
So, for example, a certain distance (4-5 mm) must be maintained between the photocells, which is not so easy without clamps. The slightest distortion, and there is the possibility of breaking the conductor, or breaking the plate. Therefore, to set a certain step, building crosses are glued onto a piece of laminate (used when laying tiles), or markings are made.
All the problems that arise when making solar panels with your own hands are associated with soldering. Therefore, before sealing, and even better before transferring the ruler to the case, check the assembly with an ammeter. If everything is ok, you can continue working.
Outcomes
Now you know how to make a solar panel at home. This is not the most difficult task, but it requires painstaking work.
Alternative energy is now being dealt with not only by specialists. Options for autonomous power supplies are also of interest to amateurs who are friends with electrical and radio engineering. With regard to solar panels, the main difficulty in the implementation of the project is their high price. And if we consider that several panels are needed for a private house, then some skepticism in terms of their use in everyday life becomes clear.
Although there is a good solution for those who are used to doing everything with their own hands - to assemble a solar panel from separate panels. For example, Chinese, which are relatively inexpensive.
From the experience of their practical application, we can conclude that they fully meet the expectations of the master. And if you focus on a class B kit (cheaper products), then the savings when assembling the power source yourself are significant.
To obtain a sample of 145 W with a total voltage of 18 V, you will have to pay for Chinese panels (36 pieces) about 3,100 rubles (if purchased via the Internet, for example, on Alibaba, Ebay) versus 6,180 (the cost of a ready-made analogue of industrial production). It turns out that it makes sense to spend time and make such a battery.
Not only Chinese, but all solar panels are divided into mono- (more expensive) and polycrystalline (amorphous). What is the difference? Without going into the manufacturing technology, it is enough to point out that the former are characterized by a homogeneous structure. Therefore, their efficiency is higher than that of amorphous analogs (about 25% versus 18%) and they are more expensive.
Visually, they can be distinguished by their shape (shown in the figure) and shade of blue. Monocrystalline panels are slightly darker. But whether there is any sense in saving on power, you will have to decide on your own. In addition, it should be noted that mainly small firms are engaged in the production of inexpensive polycrystalline panels in China, saving on literally everything, including starting materials. This directly affects not only the cost price, but also the quality of the product.
All photocells are connected in a single energy chain by conductors. Depending on the type of panels, they may be already fixed in place or missing. This means that you will have to solder them with your own hands. All crystalline samples are fragile and must be handled with extreme care.
If you do not have the proper skills to work with a soldering iron, then it is better to purchase panels of class A (more expensive). When buying cheap analogs (B), it is advisable to take at least one in stock. The practice of assembling solar panels shows that damage cannot be avoided for sure, so an extra panel will definitely be needed.
When determining the required number of photocells, you can focus on such data. 1 m² of panels gives approximately 0.12 kWh of electricity. Energy consumption statistics show that for a small family (4 people), about 280 - 320 kW is enough per month.
Solar panels are sold in two options - wax coated (to protect against damage during transit) and without it. If the panels have a protective layer, then they will have to be prepared for assembly.
What needs to be done?
- Unpack the product.
- Immerse the kit in hot water. The approximate temperature is 90 ± 5 ° C. The main thing is that it is not boiling water, otherwise the panels will be partially deformed.
- Disconnect samples. Signs that the wax has melted are visible visually.
- Treat each panel. The technology is simple - they are alternately immersed in hot soapy water, then clean. The “ablution” procedure continues until there are no traces of wax on the surface.
- Dry. The panels should be laid out on a soft cloth. For example, on a terry tablecloth.
Assembly order
Specificity of frame manufacturing
In fact, this is a traditional simple frame, the material for which is selected depending on the location of the battery. Usually on thematic sites, an aluminum corner or wood is indicated. The expediency of using the latter (with all due respect to the authors of the articles) raises certain doubts. The main reason is in the peculiarities of any tree. It consists in the moisture content, regardless of the degree of drying.
No matter how much it may be, twisting or even cracking of the tree cannot be avoided. Given the fragility of the panels - not an option, definitely. For a long time, even when attached to a window inside a building, it will not serve.
Battery installation
The dimensions of the frame are selected based on the linear parameters of the panels. Horizontal or vertical orientation - it depends on the specifics of the battery installation, and does not matter in principle.
A sheet of glass or polycarbonate is attached to the frame (only not cellular, but monolithic). It performs a protective function, protecting the photocells from mechanical damage.
On it, from the inside of the frame, drops of silicone sealant are applied (in the center of the panels), or it is smeared with a thinnest layer. Recommendations for the use of resin (epoxy) hardly deserve attention, since in this case there is no need to talk about the maintainability of the battery.
The estimated number of panels fits into the frame (assembly is done in advance). One gives a voltage of about 0.5 V (a small deviation in the nominal value does not count). Here it is important not to confuse where the front side of the products is and where the back is.
The back is covered with a soft removable mat. To make it with your own hands, you can take foam rubber (4 cm, at least) and polyethylene film. Its edges are connected with tape or soldered (if there is a special machine).
The work doesn't end there. Air bubbles will remain between the glass (polycarbonate) and the panels, which will reduce the efficiency of the solar panel. They need to be removed. For this, a dense material is laid on the mat. For example, a fragment of thick (multi-layer) plywood, matched to the dimensions of the frame.
Above - a weight, the weight of which is sufficient to slightly press down the panels. In this position, the battery is left for half a day, no less. Here you should focus on its dimensions and uniformity of load distribution.
After this time, bends, plywood and mat are dismantled. It is impossible to immediately fix the battery at the installation site. It will take some more time for the sealant to dry completely.
Instead of a mat, you can also use another soft backing. For example, sawdust, shavings.
The final stage is the manufacture of the back wall and its setting in place. For this, chipboard, fiberboard, plywood are taken, but always with the same substrate to protect the panels from deformation.
Circuit assembly features
The bonding of plates is a complex process that requires painstaking and attentiveness. It is better to work with a low-power soldering iron (24 - 36 W). If used in everyday life at 65, then it should be turned on through a limiting resistance. The simplest option is to connect a hundred-watt light bulb in series.
But that's not all. It is necessary to exclude self-discharge of the battery (at night, in inclement weather). This is ensured by the inclusion of p / p diodes in the circuit. It is advisable to use an acoustic cable as a conductor (for conclusions), which is also fixed on the panel with a sealant.
The option of a film solar battery (there is one) is not considered. Despite some advantages, it has a number of significant disadvantages - low efficiency and the need for laying over large areas. For a private house, the solution is unacceptable.
Environmental degradation, rising energy prices, the desire for autonomy and independence from the whims of statesmen - these are just a few factors that make the most inveterate inhabitants turn dreamy views towards alternative energy sources. For most of our compatriots, the idea of "green" energy remains a fix idea - high prices for equipment and, as a result, the unprofitability of the venture affect. But after all, no one forbids making an installation for obtaining free energy on your own! Today we will talk about how to build a solar battery with our own hands and consider the prospects for its use in everyday life.
Solar battery: what is it
Humanity has been on fire with the idea of transforming solar radiation into electrical energy since the 30s of the last century. It was then that scientists from the USSR Academy of Sciences announced the creation of semiconductor copper-thallium crystals, in which an electric current began to flow under the action of light rays. Today this phenomenon is known as the photoelectric effect and is widely used both in solar installations and in a variety of sensors.
The first solar panels have been known since the 50s of the last century.
The current strength of one photocell is measured in microamperes, therefore, to obtain any significant electrical power, they are combined into blocks. Many of these modules form the basis of the solar battery (SB), which can be used to connect various electronic devices. If we talk about a finished device that can be installed in the open air, then it is more correct to talk about a solar panel (SP) with a structure that protects the assembly of photovoltaic modules from external factors.
It must be said that the efficiency of the first electric solar systems did not reach even 10% - both the shortcomings of semiconductor technology and irreparable losses associated with reflection, scattering or absorption of the light flux affected. Decades of hard work by scientists have yielded their results, and today the efficiency of the most modern solar panels reaches 26%. As for promising developments, here it is even higher - up to 46%! Of course, the attentive reader might argue that other power generators operate at 95–98% energy efficiency. Nevertheless, one should not forget that we are talking about completely free energy, the value of which on a sunny day exceeds 100 watts per square meter. m of the earth's surface per second.
Modern solar panels generate electricity on an industrial scale
The electricity obtained with the help of solar panels can be used in the same way as that obtained in conventional power plants - to power various electronic devices, lighting, heating, etc. current is actually an advantage. The thing is that any solar system works only during daylight hours, and its power depends very much on the height of the sun above the horizon. Since the SB cannot work at night, the electricity has to be accumulated in batteries, and they are all just direct current sources.
Device and principle of operation
The principle of operation of an electric battery is based on such physical phenomena as semiconductor and photoelectric effect. Any solar cell is based on semiconductors, the atoms of which lack electrons (p-type conductivity), or have an excess of them (n-type). In other words, a two-layer structure with an n-layer as a cathode and a p-layer as an anode is used. Since the holding forces of the "extra" electrodes in the n-layer are weakened (atoms do not have enough energy for them), they are easily knocked out of their places when bombarded by photons of light. Then the electrons move into the free "holes" of the p-layer and through the connected electrical load (or battery) return to the cathode - this is how the electric current flows, provoked by the flow of solar radiation.
The conversion of solar energy into electrical energy is possible thanks to the photoelectric effect, which Einstein described in his works
As noted above, the energy from one photocell is extremely small, so they are combined into modules. By connecting several such units in series, the battery voltage is increased, and by parallel, the amperage is increased. Thus, knowing the electrical parameters of one cell, you can assemble a battery of the required power.
The electricity received from the solar battery can be stored in batteries and, after being converted to a voltage of 220 V, can be used to power ordinary household appliances.
To protect against weathering, semiconductor modules are installed in a rigid frame and covered with glass with increased light transmission. Since solar energy can be used only during daylight hours, batteries are used to accumulate it - you can use up their charge as needed. Inverters are used to increase the voltage and adapt it to the needs of household appliances.
Video: how a solar panel works
PV module classification
Today, solar cell production follows two parallel paths. On the one hand, there are silicon-based photovoltaic modules on the market, and on the other, film-based modules created using rare-earth elements, modern polymers and organic semiconductors.
Today's popular silicon photovoltaic cells are divided into several types:
- monocrystalline;
- polycrystalline;
- amorphous.
For use in homemade solar panels, it is best to use polycrystalline silicon modules. Although the efficiency of the latter is lower than that of monocrystalline elements, their performance is not so strongly influenced by surface contamination, low cloudiness or the angle of incidence of sunlight.
It is not difficult to distinguish polycrystalline silicon modules from monocrystalline ones - the former have a lighter blue tint with pronounced "frosty" patterns on the surface. In addition, the type of photovoltaic plates can be determined by their shape - a single crystal has rounded edges, while its closest competitor (polycrystal) is a pronounced rectangle.
As for amorphous silicon batteries, they are even less dependent on weather conditions and due to their flexibility are practically not subject to the risk of damage during assembly. Nevertheless, their use for their own purposes is limited both by a rather low specific power per 1 square meter of surface, and due to their high cost.
Silicon solar cells are the most common class of electrical photographic plates, so they are most often used to make homemade devices.
The emergence of film photovoltaic modules is due to both the need to reduce the cost of solar cells and the need to obtain more efficient and durable systems. Today the industry is mastering the production of thin solar modules based on:
- cadmium telluride with an efficiency of up to 12% and a cost of 1 W is 20–30% lower than that of single crystals;
- copper and indium selenide - efficiency 15–20%;
- polymer compounds - thickness up to 100 nm, with an efficiency of up to 6%.
It is still too early to talk about the possibility of using film modules to build an electric solar station with your own hands. Despite the affordable cost, only a few companies are engaged in the manufacture of telluride-cadmium, polymer and copper-indium solar cells.
Such advantages of film photocells as high efficiency and mechanical strength make it possible to say with full confidence that they are the future of solar energy.
Although you can find batteries made using film technology on the market, most of them are presented in the form of finished products. We are interested in individual modules from which you can build an inexpensive homemade solar panel - they are still in short supply on the market.
A summary of the efficiency of industrial solar cells is presented in the table.
Table: Efficiency of modern solar panels
Where can I get photocells and can they be replaced with something else?
Buying monocrystalline or polycrystalline wafers suitable for solar panel assembly is not a problem today. The question is that the very idea of a home-made free electricity generator presupposes a result that will be much cheaper than the factory counterpart. If you buy PV modules locally, you won't be able to save much.
On foreign trading floors, solar cells are presented in a wide range - you can buy both a single product and a set of everything necessary for assembling and connecting a solar battery
For a reasonable price, solar cells can be found on foreign marketplaces such as eBay or AliExpress.... There they are presented in a wide range and at quite affordable prices. For our project, for example, common 3x6 "polycrystalline wafers are suitable. Under ideal conditions, they can generate an electric current with a voltage of 0.5 V and a power of up to 3 A, that is, 1.5 W of electrical power.
If you are eager to save as much as possible or try your own strengths, then there is no need to immediately buy good, whole modules - you can get by with substandard ones. All on the same eBay or AliExpress you can find sets of plates with small cracks, chipped corners and other defects - the so-called "B" class products. External damage does not affect the technical characteristics of photocells, which cannot be said about the price - defective parts can be bought 2-3 times cheaper than those that have a presentation. That is why it is rational to use them to test the technology on your first solar panel.
When choosing photovoltaic modules, you will see elements of different types and sizes. Don't assume that the larger their surface area, the higher the voltage they generate. This is not true. Cells of the same type generate the same voltage regardless of size. The same cannot be said about the strength of the current - here the size is of decisive importance.
Although an obsolete component base can be used as photocells, opened diodes and transistors have too low voltage and amperage - thousands of such devices will be needed
Immediately I want to warn you that there is no point in looking for an analogue among the various electronic devices at hand. Yes, you can get a working photoelectric module from powerful diodes or transistors removed from an old radio or TV. And even make a battery by connecting several such elements in a chain. However, it will not be possible to power anything more powerful than a calculator or LED flashlight with such a "solar panel" due to the too weak technical characteristics of a single module.
The principle of calculating battery power
To calculate the required power of a home-made electric solar system, you need to know the monthly electricity consumption. It is easiest to determine this parameter - the amount of electricity consumed in kilowatt-hours can be viewed by the meter or found out by looking at the bills that the energy supply regularly sends. So, if the costs are, for example, 200 kWh, then the solar battery should generate about 7 kWh of electricity per day.
In the calculations, it should be borne in mind that solar panels generate electricity only during daylight hours, and their performance depends on both the angle of the Sun above the horizon and weather conditions. On average, up to 70% of the total amount of energy is generated from 9 am to 4 pm, and in the presence of even slight cloudiness or haze, the power of the panels decreases 2-3 times. If the sky is covered with continuous clouds, then at best you can get 5-7% of the maximum capacity of the solar system.
According to the graph of the energy efficiency of the solar battery, it can be seen that the main share of the generated energy falls on the time from 9 to 16 hours.
Considering all of the above, it can be calculated that to obtain 7 kWh of energy under ideal conditions, an array of panels with a capacity of at least 1 kW is required. If we take into account the decrease in productivity associated with a change in the angle of incidence of the rays, weather factors, as well as losses in batteries and energy converters, then this figure must be increased by at least 50–70 percent. If we take into account the upper figure, then for the example under consideration, a solar panel with a capacity of 1.7 kW will be needed.
Further calculation depends on which photocells will be used. For example, take the previously mentioned 3˝ × 6˝ polycrystalline cells (area 0.0046 sq. M) with a voltage of 5 V and a current strength of up to 3 A. 12 V = 141 A, you will need to connect 24 elements in a row (a series connection allows you to sum up the voltage) and use 141 A / 3 A = 47 such rows (1 128 plates). The battery area with the most dense packing will be 1,128 x 0.0046 = 5.2 square meters. m
In order to accumulate and transform solar energy into the usual 220 volts, you will need an array of batteries, a charge controller and a step-up inverter.
To accumulate electricity, batteries with a voltage of 12 V, 24 V or 48 V are used, and their capacity should be enough to accommodate the same 7 kWh of energy. If we take common 12-volt lead-acid batteries (far from the best option), then their capacity should be at least 7,000 W × h / 12 V = 583 A × h, that is, three large batteries of 200 ampere-hours each. It should be borne in mind that the efficiency of storage batteries is no more than 80%, and also that when the voltage is converted by an inverter to 220 V, 15 to 20% of energy will be lost. Therefore, you will have to buy at least one more battery of the same to compensate for all losses.
On the question of the possibility of using electric solar panels for heating
As you may have already noticed, the phrase "solar battery" or "solar panel" is constantly mentioned in the context of an electrical device. This was not done by chance, since other solar panels or batteries - geo-collectors - are often called in the same way.
Several solar collectors will be able to provide the house with hot water and will bear part of the heating costs
The ability to directly convert solar energy directly into heat can significantly increase the productivity of such installations. Thus, modern geo-collectors with a selective coating of vacuum tubes have an efficiency of 70–80% and can be used both in hot water supply systems and for heating rooms.
The design of the solar collector with vacuum tubes minimizes heat transfer to the external environment
Returning to the question of whether it is possible to use an electric solar panel to power heating appliances, let's consider how much heat is needed, for example, for a house of 70 square meters. meters. Based on the standard recommendations of 100 W of heat per 1 sq. m of the area of the room, we get the cost of 7 kW of energy per hour or about 70 kWh per day (heating devices will not be turned on all the time).
That is, 10 homemade batteries with a total area of 52 sq. M. Can you imagine a colossus that is, say, 4 m wide and more than 13 m long, as well as a block of 12-volt batteries with a total capacity of 7200 ampere-hours? Such a system will not even be able to reach self-sufficiency before the battery life is exhausted. As you can see, it is still too early to talk about the advisability of using solar panels for heating purposes.
Choosing a place for installing an electric solar panel
It is necessary to choose the place where the solar panel will be installed at the design stage. This can be either a south-facing roof slope, or an open area in a suburban area. The second, of course, is preferable for several reasons:
- the solar panel installed below is easier to maintain;
- it is easier to mount a rotary device on the ground;
- the additional load on the roof and its damage during the installation of the solar system are excluded.
The installation site of the electrical panel should be open to sunlight during the whole daylight hours, so there should be no trees or buildings nearby, the shadow from which could fall on its surface.
When choosing a place for installing a solar system, be sure to take into account the possibility of solar panels shading by surrounding objects
The second circumstance compelling us to look for such a site before starting the assembly of the solar battery is associated with determining the dimensions of the panel. Assembling the device with our own hands, we can be flexible enough to choose its size. As a result, you can get an installation that fits perfectly into the exterior.
Getting started making a solar panel with your own hands
Having made all the necessary calculations and having decided on the place for installing the solar battery, you can start making it.
What is needed in the work
In addition to the purchased photocells, when building an electric solar panel, you will need the following materials:
- copper stranded wire;
- solder;
- special buses for connecting photocell leads;
- Schottky diodes, designed for the maximum current of one cell;
- solder;
- wooden slats or aluminum corners;
- plywood or OSB;
- Fiberboard or other rigid sheet dielectric material;
- plexiglass (you can use polycarbonate, anti-reflective super-transparent glass or IR-absorbing window glass with a thickness of at least 4 mm);
- silicone sealant;
- self-tapping screws;
- antibacterial impregnation for wood;
- Oil paint.
When choosing glass for solar panels, select IR-absorbing grades with maximum light transmission and minimum light reflection.
To work, you will need such a simple tool:
- soldering iron;
- hacksaw or jigsaw;
- a set of screwdrivers or screwdriver;
- paint brushes.
If an additional bracket or pivot support is to be constructed under the solar panel, then, accordingly, the list of materials and tools should be supplemented by a wooden bar or metal corners, steel bar, welding machine, etc. When installing the SB on the ground, the site can be concreted or tiled.
Workflow instructions
As an example, consider the process of building an electric solar system from the 3x6-inch solar cells considered above with a voltage of 0.5 V and a current strength of up to 3A. To charge a 12-volt battery, it is necessary that our battery "give out" at least 18 V, that is, 36 plates are needed. The assembly should be carried out in stages, otherwise errors in the work cannot be avoided. It should be remembered that any alterations, as well as unnecessary manipulations with photocells can lead to their damage - these devices are distinguished by increased fragility.
To make a full-fledged solar battery, you will need several dozen photocells.
Manufacturing of the case
The casing of the solar battery is a flat box, closed with plywood on one side and transparent glass on the other. For the manufacture of the frame, you can use both aluminum corners and wooden slats. The second option is easier to work with, so we recommend choosing it for making your first panel.
When starting the construction of a solar panel, make a small drawing - in the future this will help save time and avoid dimensional errors
A rectangular frame with external dimensions of 118x58 cm, reinforced with one crossbar, is assembled from slats with a section of 20x20 mm.
The solar battery body is a wooden shield with sides no more than 2 cm high - in this case, they will not shade the photocells
Ventilation devices are drilled in the lower ends of the case, as well as in the spacer bar. They will communicate the inner cavity with the atmosphere, so that the glass will not fog up on the inside. After that, a rectangle is cut out of the plexiglass sheet, corresponding to the outer dimensions of the frame.
The holes made in the rails are used for ventilation of the inner space of the panel.
The reverse side of the box is sewn up with plywood or OSB. The body is treated with an antiseptic and painted with oil paint.
To protect the wooden case from the weather, it is painted with oil paint.
2 substrates for photocells are cut to the size of the internal cavities of the housing. Their use during the installation of plates will not only make the work more convenient, but also reduce the risk of damage to fragile glass. For substrates, you can take any dense material - fiberboard, textolite, etc. The main thing is that it does not conduct electric current and resists heating well.
Any suitable dielectric can be used as substrates for photocells, for example, perforated fiberboard
Assembly of plates
The assembly of the plates begins with unpacking. Often, for the safety of photocells, they are collected in a pile and filled with paraffin. In this case, the products are immersed in a container with water and heated in a water bath. After the paraffin is melted, the plates should be separated from each other and dried well.
It is best to remove wax from the plate pack in a water bath. The method shown in the figure has not proven itself in the best way - when boiling, the plates begin to vibrate and hit each other
The photocells are laid out on the substrate in such a way that their leads are directed in the desired direction. In our case, all 36 plates are connected in series - this will allow us to "dial" the 18 V we need. For ease of installation, 6 plates should be soldered each, getting 6 separate chains.
Before soldering, the photocells are arranged in chains of the required length.
Knowing the principle of forming solar panels, you can easily select the required voltage and current. Everything is very simple: first, a group of plates connected in series is assembled, which will give the required voltage. After that, the individual blocks are connected in parallel - this will add up their current strength. Thus, you can get a panel of any power.
Solder is applied to the conductive paths of the photocells and the parts are connected to each other using a low-power soldering iron.
When buying cheaper photocells without leads, be prepared for the painstaking work of soldering conductors
After collecting all six groups, a drop of silicone sealant must be applied to the center of each plate. Then the chains of photocells are unrolled and carefully glued to the substrate.
To fix the photocells on the substrate, use a silicone sealant or rubber glue.
A Schottky diode is soldered to the positive terminal of each chain - it will protect the battery from discharge through the panel at night or in case of strong clouds. Using a special busbar or copper braid, the individual blocks are connected into a single circuit.
In the wiring diagram, solar panel elements are circled with a dotted line.
With a serial connection, the positive terminal must be connected to the negative contact, and in parallel - to the one of the same name.
Installing Plates in the Case
The photocells assembled on the substrate are placed in the case and fixed to the plywood using self-tapping screws. The individual parts of the solar panel are connected to each other with a copper conductor. It can be passed through one of the ventilation holes in the cross member - this will not interfere with the installation of the glass.
A multicore cable is soldered to the "plus" and "minus", which is led out through the hole in the bottom of the case - it will be needed to connect the panel to the battery. To prevent damage to the plates, the cable is firmly fixed to the wooden frame.
After installing the plates, all hinged elements are fixed with hot glue or sealant
From above, the solar battery is covered with a sheet of plexiglass, which is fixed with corners or self-tapping screws. To protect the photocells from moisture, a layer of silicone sealant is applied between the frame and the glass. At this, the assembly can be considered complete - you can take out the solar battery to the roof and connect it to consumers.
After laying and fixing the glass cover, the solar panel is ready for use.
The efficiency of a solar battery depends on its orientation to the sun - the maximum power is achieved when the sun's rays fall at a right angle. To increase the productivity of the installation, it is placed on a pivot frame. This structure is a wooden or metal frame mounted on a pivoting horizontal axis.
For maximum efficiency, the solar panel must be oriented strictly towards the Sun. Automatic installations, called heliotrackers, do the best with this task.
For turning and fixing the frame, you can use both a mechanical drive (for example, a chain drive), and a support bar with step adjustment. The most advanced rotary devices are equipped with a vertical rotation unit and an automatic tracking system for the Sun. Such equipment can be assembled using stepper motors and a modern microcontroller such as the Arduino.
Building a solar tracker at home is an extremely difficult task, so most often craftsmen get by with a simple frame with an inclined or fixed frame.
The connection of the solar battery to the autonomous power supply system should be carried out through the charge controller. This device will not only correctly distribute the flows of electrical energy, but also prevent a deep discharge of the battery, increasing its service life. All connections, including the connection of a 220-volt inverter, should be made with copper wires with a cross section of at least 3-4 square meters. mm - this will avoid ohmic energy losses.
The solar battery charge controller will allow it to operate at maximum current output and protect the batteries from over-discharge
Finally, I would like to recommend monitoring the solar battery not only by the indicators and arrows of the devices. Remember that dirty glass can reduce the productivity of the installation by 50% or more. Do not forget to carry out regular cleaning, and a self-assembled installation will repay you with kilowatts of completely free, and most importantly, environmentally friendly energy.
Video: DIY solar panel assembly
Today there are no barriers to assembling a solar panel with your own hands. There are no problems either with the purchase of photocells, or with the purchase of a controller or an energy converter. Hopefully, this article will provide you with a starting point on your journey to an autonomous home, and you will finally get down to business. We will be waiting for questions, ideas and suggestions from you regarding the design and improvement of solar panels. Until next time!
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Own power supply will help out both in the absence of a centralized network (in remote and hard-to-reach regions, in the country, on a hike), and when building a more environmentally friendly approach to the consumption of natural resources.
It is not difficult to assemble your own solar station, it contains only four components:
- solar panels;
- battery charge;
- controller;
- inverter.
All of them are easy to find and order through online stores. But how to make a solar power plant with your own hands in order to create a full-fledged autonomous power supply system at home? To begin with, you need to collect information about your needs, the possibilities of the area where the solar station will operate, and make all the necessary calculations for the selection of the constituent elements.
How to calculate the number of solar panels
The choice of a solar station begins with a search for information on insolation in your area - the amount of solar energy that hits the earth's surface (measured in watts per square meter. Meter). These data can be found in special meteorological books or on the Internet. Usually insolation is indicated separately for each month, because the level is highly dependent on the season. If you plan to use the solar station all year round, then you need to navigate by the months with the lowest rates.
Next, you need to calculate your electricity needs for each month. Remember that for an autonomous power supply system, the role is played not only by the efficiency of energy storage, but also by its economical use. Smaller needs will allow you to significantly save money when buying solar panels and creating a budget version of a solar power plant with your own hands.
Compare your electricity needs with the level of insolation in your area and you will find out the area of solar panels that is required for your solar station. Please note that the panel efficiency is only 12-14%. Always target the lowest score.
Thus, if the level of insolation in the most unfavorable month in your area is 20 kWh / m², then with an efficiency of 12% one panel with an area of 0.7 m² will generate 1.68 kWh. Your energy requirement, for example, is 80 kWh / month. This means that 48 panels (80 / 1.68) will be able to satisfy this need in the most non-sunny month. You can read more about how to choose solar panels in our previous one.
How to install the solar panel
For the best efficiency, install the solar panel so that the sun's rays fall on it at an angle of 90 degrees. Since the sun is constantly moving across the sky, there are two solutions:
- Dynamic setup. Use the servo to rotate the solar panel as the sun moves across the sky. The servo will collect 50% more power than a static rig.
- Stationary installation. To get the most out of the stationary position of the solar panel, it is necessary to find the installation angle at which the panel collects as many rays of the sun as possible. For year-round operation, this angle is calculated using the formula +15 degrees to the latitude of the area. For the summer months, this is -15 degrees latitude.
How to choose a charge controller
Another way how to assemble a solar power plant yourself in order to make it work efficiently is to use one that allows you to track maximum power points (MPPT). Such a controller can store energy even during low light conditions and continues to supply it to the battery in optimal mode.
So, solar panels supply energy to the battery. This allows energy to be stored so that it can be used even in the absence of sunlight. In addition, the batteries smooth out uneven energy flow, for example, in strong winds or cloudy skies.
To correctly choose and install a battery for a home solar power plant with your own hands, you must take into account two parameters:
- It is very important that the charging current (from the panels) does not exceed 10% of the nominal capacity level for acid batteries and 30% for alkaline devices.
- Low side voltage inverter design.
Consider the self-discharge rates of the batteries (not always indicated by the manufacturers). For example, acid devices are recharged every six months to avoid damage.
How to choose an inverter
Description of parameters and required functions of an ideal inverter:
- sinusoidal signal with distortions not exceeding three percent;
- when the load is connected, the voltage amplitude changes by no more than ten percent;
- double conversion of current - direct and alternating;
- analog part of AC conversion with a good transformer;
- short circuit protection;
- reloading stock.
When simulating your home's electrical system, group loads so that different types of loads are powered by different inverters.
Solar power plants are a working alternative way of supplying energy to a home. But not in all regions the insolation is sufficient for the payback of solar equipment and for the full supply of electricity. Sometimes it is worth paying attention to hybrid solar power plants, which can also be built with your own hands, but where, in addition to solar panels, there can be wind turbines, as well as diesel or even gasoline generators.
If you just want to try to "tame" solar energy, but are not ready to completely change the power supply of your home, make a mini solar power plant with your own hands. It will consist of several solar panels, a battery and a controller. All this will fit in a suitcase, but will provide you with energy in case of a sudden power outage, a trip to the country or to nature. Calculations and selection of components follow the same principle as for a full-fledged home station.
It all started with a walk on eBay - saw solar panels and got sick.
Arguments with friends about payback were ridiculous…. Buying a car, no one thinks about payback. Auto as a mistress, prepare the amount for pleasure in advance. And here, on the contrary, I spent money so they are also trying to pay off ... In addition, I connected an incubator to the solar panels so they still justify their purpose, protecting your future economy from destruction. In general, having an incubator, you depend on many factors, here either a master or a layman. When there is time, I will write about a homemade incubator. Well, okay, why talk, everyone has the right to choose ... ..!
After a long wait, the coveted box with thin fragile plates finally warms the hands and heart.
First of all, of course, the Internet ... well, it's not the gods who burn the pots. Someone else's experience is always useful. And then disappointment came ... .. As it turned out, five people made the panels with their own hands, the rest were simply copied to their sites, some of them in order to be copied from different developments in an original way. Well, God bless them, let it remain on the conscience of the owners of the pages.
I decided to read the forums, long arguments of theorists "how to milk a cow" led to complete despondency. Discussions about how plates break from heating, the difficulty of sealing, etc. I read and spat on the whole thing. We will go our own way, by trial and error, relying on the experience of "colleagues", why reinvent the wheel?
We set the task:
1) The panel must be made of materials at hand, so as not to pull the wallet, because the result is unknown.
2) The manufacturing process should be easy.
We start making a solar panel:
First of all, 2 glasses of 86x66 cm were purchased for the future two panels.
Plain glass, purchased from manufacturers of plastic windows. Or maybe not simple ...
A long search for aluminum corners, according to the experience already tested by "colleagues", ended in nothing.
Therefore, the manufacturing process began sluggishly, with a sense of protracted construction.
I will not describe the process of soldering the panels, since there is a lot of information about this on the network and there is even a video. I'll just leave my notes and comments.
The devil is not so terrible as he is painted.
Despite the difficulties that are described on the forums, the element plates are easily soldered, both the front side and the back. Also, our Soviet POS-40 solder is quite suitable, in any case, I did not experience any difficulties. And of course, our native rosin, where without it ... During the soldering time I did not break a single element, I think you have to be a complete idiot to break them on even glass.
The conductors that come with the panels are very convenient, firstly, they are flat, and secondly, they are tinned, which significantly reduces the soldering time. Although it is quite possible to use an ordinary wire, I conducted an experiment on spare plates, did not experience any difficulties in soldering. (in the photo there are remnants of a flat wire)
It took me about 2 hours to solder 36 plates. Although I read on the forum that people solder for 2 days.
It is advisable to use a soldering iron for 40 watts. Since the plates easily dissipate heat, and this makes soldering difficult. The first attempts to solder with a 25 Wadded soldering iron were tedious and sad.
Also, when soldering, it is advisable to optimally select the amount of flux (rosin). For a large excess of it does not allow the tin to stick to the plate. And so I had to practically tin the disc, in general, it's okay, everything is fixable. (take a closer look at the photo you can see.)
Tin consumption is quite high.
Well, in the photo there are soldered elements, in the second row there is a jamb, one output is not soldered, but I noticed and corrected the main thing.
The edging of the glass is made with double-sided tape, then a plastic film will be glued to this tape.
Scotch tapes that I used.
After soldering, start sealing (tape will help you).
Well, the glued plates with scotch tape and a fixed joint.
Next, remove the protective layer of double-sided tape from the edging of the panel and glue a plastic wrap on it with a margin on the edges. (I forgot to take a picture) Oh, yes, we make slots in the scotch tape for outgoing wires. Well, not stupid, you will understand what and when ... Along the edge of the glass, as well as the leads, corners, we coat with silicone sealants.
And we fold the film to the outside.
A plastic frame was pre-made. When I installed plastic windows in the house, a plastic profile for the window sill is attached to the window with screws. I thought this part was too thin. Therefore, he removed and made the sill in his own way. Therefore, plastic profiles remained from 12 windows. So to speak, the material is in abundance.
I glued the frame with an ordinary, old, Soviet iron. It’s a pity that I didn’t shoot the process, but I think there’s nothing beyond the incomprehensible. I cut off 2 sides at 45 degrees, heated it on the sole of the iron and glued it, having previously installed it at an even angle. In the photo there is a frame for the second panel.
We install glass with elements and a protective film in the frame
We cut off the excess film, and glue the edges with silicone sealants.
We get just such a panel.
Yes, I forgot to write that, in addition to the film, I glued guides to the frame that prevent the elements from falling if the adhesive tape comes off. The space between the elements and the guides is filled with polyurethane foam. That made it possible to press the elements more tightly to the glass.
Well, let's start testing.
Since I made one panel in advance, the result of one I know is the Voltage of 21 Volts. Short circuit current 3.4 Ampere. The strength of the charging current of the storage battery is 40A. h 2.1 Ampere.
Unfortunately I didn’t take pictures. I must say that the current strength depends on the illumination.
Now 2 batteries connected in parallel.
The weather at the time of production was cloudy, it was about 4 pm.
At first it upset me, and then it even made me happy. After all, these are the most average conditions for a battery, which means the result is more believable than in bright sun. The sun shone through the clouds not so brightly. I must say that the sun was shining a little from the side.
With this lighting, the short-circuit current was 7.12 Amperes. Which I consider to be an excellent result.
No-load voltage 20.6 Volts. Well, that's stable at about 21 volts.
The battery charge current is 2.78 Ampere. That with such lighting guarantees the battery charge.
Measurements have shown that with a good sunny day, the result will be better.
By that time, the weather was getting worse, the clouds were closed, the sun was completely and I wondered what it would show in this situation. It's almost evening twilight ...
The sky looked like this, specially filmed the horizon line. By the way, on the very glass of the battery you can see the sky like in a mirror.
The voltage in this situation is 20.2 volts. As already mentioned 21c. it is practically a constant.
Short circuit current 2.48A. In general, it is great for such lighting! Almost equal to one battery in good sun.
The battery charge current is 1.85 Ampere. What can I say ... Even at dusk, the battery will be charged.
Conclusion built solar battery, not inferior in characteristics to industrial designs. Well, the durability ... .., we'll take a look, time will tell.
Oh yes, the battery is charged through 40 A Schottky diodes. Well, what was found.
I also want to say about controllers. All this looks nice, but not worth the money spent on the controller.
If you are friends with a soldering iron, the circuits are very simple. Make and have fun making.
Well, the wind blew and the remaining spare 5 elements fell into an uncontrollable flight ... ... the result was splinters. Well what to do, carelessness should be punished. On the other hand…. Where are they?
We decided to make another socket out of the fragments, 5 volts. It took 2 hours to make. The rest of the materials just came in time. Here's what happened.
Measurements were taken in the evening.
I must say that with good lighting, the short-circuit current is more than 1 ampere.
The pieces are soldered in parallel and in series. The goal is to provide approximately the same area. After all, the current strength is equal to the smallest element. Therefore, when manufacturing, select elements according to the area of \ u200b \ u200bthe illumination.
Now is the time to talk about the practical application of the solar panels I have made.
In the spring, I installed two fabricated panels on the roof, height 8 meters at an angle of 35 degrees, oriented to the southeast. This orientation was not chosen by chance, because it was noticed that in this latitude, in the summer, the sun rises at 4 am and by 6-7 o'clock quite tolerably charges the batteries with a current of 5-6 amperes, also applies to the evening. Each panel must have its own diode. In order to exclude burnout of elements with different power of the panels. And as a consequence, an unjustified decrease in the power of the panels.
The descent from a height was made with a stranded wire with a cross section of 6 mm2 each. Thus, it was possible to achieve minimal losses in the wires.
Old barely-living batteries 150Ah, 75Ah, 55Ah, 60Ah were used as energy storage devices. All batteries are connected in parallel and taking into account the loss of capacity, they total about 100Ah.
There is no battery charge controller. Although I think the installation of the controller is necessary. I'm working on the controller circuit now. Since the batteries start to boil during the day. Therefore, you have to dump excess energy daily by turning on unnecessary load. In my case, I turn on the sauna lighting. 100 watts. Also, during the day, an LCD TV of about 105W, a fan of 40W works, and an energy-saving 20W light bulb is added in the evening.
For those who like to carry out calculations, I will say: THEORY AND PRACTICE are not the same thing. Since such a "sandwich" works perfectly fine for over 12 hours. at the same time sometimes we charge phones from it. The full discharge of the batteries has not yet reached. Which, accordingly, crosses out the calculations.
As a converter, a computer uninterruptible power supply (inverter) 600VA, slightly altered for free start-up from batteries, was used, which approximately corresponds to a load of 300W.
I also want to note that the batteries are charged even when the moon is bright. At the same time, the current is 0.5-1 Ampere, I think it's not bad at all for the night.
Of course I would like to increase the load, but this requires a powerful inverter. I plan to make the inverter myself according to the diagram below. Since buying an inverter for a lot of money is INSANE!