Build a solar power plant with their own hands

We continue our theme dedicated to the construction of a home solar power. General information about construction of solar panels, On the principles of calculation of solar panels, as well as choice of additional equipment for stand-alone power systems, you can see by reading our previous article. Today we tell about the features of self-production of solar panels, a sequence connection of electrical transformers and protective devices that must be included with the solar power.

Production of photovoltaic modules

Standard photovoltaic module (panel) consists of three basic elements.

Where:

• Housing panel.
• Frame.
• Photovoltaic cells.

The most simple in construction element of the solar module is its body. Typically, its front side is an ordinary glass sheet, whose dimensions correspond to the number of solar cells.

Adoronkin (User FORUMHOUSE):

Glass used ordinary window - 3 mm (the most expensive). Conducted test: module performance glass deteriorates slightly, so I do not see much sense to take an enlightened or toughened glass.

Window glass is often used in the manufacture of the protective housing for the solar panels. If you doubt the strength of this material, you can use tempered glass or normal, but thicker (5... 6 mm). In this case, there is no doubt that the photovoltaic cells will be protected from destructive manifestations of natural elements (hail, for example).

Not recommended for use as part of the housing plexiglass, as when heated, this material may be deformed.

The back side of the case can be made of moisture resistant material which will protect it from dust and moisture on the solar cells. This may be metal tin, sealingly attached to the frame using rivets, or silicone and, again, ordinary glass.

The presence of the rear wall of the housing homemade solar panel some craftsmen and is not welcome.

Adoronkin:

The back of the battery side is open (for better cooling), but is covered with an acrylic lacquer mixed with the transparent sealant.

Given that heating panels significantly decreases their power, this decision seems justified. After all, it provides efficient cooling of semiconductor elements and at the same time - a quality seal solar cells. Together, guaranteed prolongs the life of the solar panels.

Frame

Frames for homemade solar panels are usually made of standard aluminum parts. Better use of the coated aluminum - anodized or painted. If there is a temptation to make a frame made of wood or plastic, be prepared for the fact that a couple of years the product may crack from dryness or even fall apart under the effect of climatic factors (except for the window plastic).

BOB691774 (FORUMHOUSE User):

Buy where the produce window. Price - 80 rubles. per square meter. Profile is ready for use, only need to gash at 45 ° and under heat, glue the corners.

Consider the simplest version of the panel: panel with aluminum frame.

Details of the aluminum frame easily fastened together with bolts or screws.

Subsequently, aluminum Corners can effortlessly stick glass body. All you need to do - the usual silicone sealant.

Adoronkin:

I took Silicone Sealant - Universal. Enough of the 1st tube. Sealant is better to take transparent. Chemical sealant security in relation to photovoltaic cells confirmed the annual battery operation.

That will have a shallow box with a glass bottom, which will later be glued photovoltaic cells.

Determining the size of the housing and frame, one should consider the need for a gap between adjacent photovoltaic cells, which is equal to - 2... 5 mm.

Soldering solar cells

The most important stage is the assembly of solar modules soldering photovoltaic cells. Solar cells are made of a very brittle material, and therefore the treatment they require appropriate. Those people who have already dealt with them, to continue with the purchase of solar cells bought himself a cell with a certain margin in the number (10 - 15%). For example, for the manufacture of the panel, calculated on the elements 36, they become 39 - 42 cells.

recommended buy special flat conductors (shank), the surface already covered with a thin layer of tin for soldering the solar cell.

Thin shank for soldering of solar cells, thicker shank (with the help of which adjacent rows of panels are combined with each other) and solar cells is better to buy from the same vendor. This saves time searching for suitable components and provides some assurance of compatibility.

Soldering elements in case of their series connection is made by the following scheme.

Negative (face) of the solar cell contact is soldered to the positive (back) contact following cell, and so on. D.

Here is the final panel.

For work you need the following tools and materials:

• Powerful soldering 40-60 watts (at least).
• The flux (flux-marker) - must be neutral (otherwise the soldered contacts quickly oxidize).
• The shank of different widths.
• Rubber gloves - not to smear the solar cells (especially their front part).

Yet we need tin. This is the case if the tavern will be badly soldered to the contacts. Cells being processed are arranged on a firm and smooth surface. This may be a plate or glass. To the cells do not slide on the working table surface, they can be fixed by means of tape pieces glued element on the perimeter. Gluing insulating tape on the cell itself (particularly its front part) should not. The free end of the shank to be attached to the table using double-sided tape.

Soldering elements and assembling the panels are made in the following order: first thing in the contact groove along the entire length of the plate is greased flux. Then flat tavern fits into the groove and is soldered to the contact plate over its entire width (at the negative pole member).

Or at three points (usually - on the positive pole element).

The number of points depends on the soldering member.

Alternately contacts soldered to all solar cells. Additional solder is used only in cases when the first time tavern can not be reliably soldered to the plate.

The first contacts are soldered to the front (negative) side of each cell, which would lay down on a glass panel body.

Tavern proper size is prepared in advance. Its length must correspond to the width 2 of adjacent plates.

Plates with soldered contacts are placed on a glass panel body face down. Thereafter, they can be soldered to one another according to the polarity ( "-" of each cell is sealed to the "+" neighboring cell and so on).

To it easier elements disposed on the glass panel body, its surface can be pre-mark.

Sliderrr (User FORUMHOUSE):

Glass struck a black felt-tip cell position point. He arranged the cell and recorded their heads, nuts and bolts.

Nuts, keys and other metal objects, in this case used as a load. Freeze cells may also be by a transparent silicone which is applied at the corners of each glass element.

By combining with each other adjacent rows of photovoltaic cells, use additional solder. This will improve the reliability of soldering joints of varying width conductors.

Sliderrr:

During soldering of all elements put together small pieces of solder (the one with the rosin in) in place of soldering. There was a pen unnecessarily.

When all the cells are soldered to each other, and the conductors are led out through the aluminum framed panel can begin to fill the solar cell.

To do this, the joints between adjacent elements are filled with silicone sealant.

Sliderrr:

Silicone filled gaps between the panels (slightly flattened and cut the nozzle of the syringe to provide aesthetics and good weld silicone contact with the glass). When dried up, I missed the perimeter of each socket again. After the sealant has dried, twice covered cell yacht varnish. In the future, try to nail insulation.

User Mirosh instead of using lacquer to fill the cells of white silicone, which is applied to the surface of a thin layer with a trowel. Result - quite satisfactory.

Before final assembly of each element, it is desirable to test for the power it generates. This can be done using a multimeter. If significant differences between the current and the voltage, which generates each cell, no one can safely integrate them into the photovoltaic module.

Installing Schottky diodes

In the construction of solar panels are often used elements of which we have not previously mentioned. This Schottky bypass diodes.

To install them resort for two reasons.

First, put the shunt diodes to at night or in cloudy weather, the solar panels do not discharge the battery that is solar power kit.

Alex MAP (User FORUMHOUSE):

In the case of direct connection of solar panels to the battery during the night on the panels planted voltage, and they are heated. Therefore, in the primitive solar controller circuitry developed more 10 years ago, was introduced Schottky diode (protection from the night of discharge battery).

If the solar panels connected to the current controller, the special need for protection against discharge of the night there. Defective controller, without the aid of additional equipment, time will disable the Security Council on the battery.

Secondly, if the solar module is closed by the shadow standing near the building (or other object massive), the power of this element is reduced. Consequences of the power are: with respect to the remaining panels connected to the shadowed element sequentially shaded element from the current source is converted into a resistive load. The resistance of the shaded module is greatly increased, as the temperature increases significantly.

Significant power reduction - this is harmless from the fact the consequences of partial shading of solar batteries serially connected. After all, the shaded module to overheat and fail. This phenomenon is called "the effect of the hot spots."

In order to avoid this effect, in parallel with each series connection of modules (or the serial number of solar cells) Schottky diode is installed. The diode allows electricity to start up bypassing the shaded bar. In this case, the generated voltage will decrease, but large drawdowns of current can be avoided.

Alex MAP:

High current from the other circuit boards, which are illuminated, is not interrupted, and will go to bypass the shaded portions of panels through the diodes. The final voltage will be slightly smaller, but the controller is not important. If in the panels were integrated diodes, then at the slightest shade at least 1 piece of the whole chain of the panel would be completely stopped giving current.

In other words, the power loss will be commensurate with the area of ​​shading.

The diodes can be installed in parallel throughout the unit, and can be parallel to the individual rows.

There is shown a diagram in which each row of cells installed in one module has its diode. In practice, the module is often divided into 2 equal parts.

HouzeR (User FORUMHOUSE):

Usually for four-panel displays mid-point, that is, half the cells are bypassed. Diodes put in the terminal box.

In any case, all of the solar panel modules must be positioned so that the light incident on them evenly. Then you do not have to solve the problem of bridging the individual modules or cells.

Terminal boxes for convenience are placed on the back of the solar panels.

If multiple groups of serially connected panels connected to the controller in parallel, in this case, each consecutive chain included in the general circuit through a decoupling diode. This prevents a mismatch loss at separate consecutive chains and to protect the battery from further discharge during the night (when, suddenly, the controller fails).

The diodes are chosen for two main parameters: the maximum current intensity which will pass in the forward direction (forward current), and the reverse voltage. The maximum reverse voltage (Uobr.maks.) Should not cause a breakdown diode. Thus the performance of the diode should slightly exceed the nominal panel (approximately 1.3 - 1.5 times).

But there is one trick.

Max94 (User FORUMHOUSE):

Normal Schottky large voltage does not happen. It's just a drop in the pillars to direct current. So it is better to take the usual with Urev. Max ≈ 30... 100V.

Covers

How to strengthen the panel and where to install them? The answers to these questions depend on the Security Council structure and the capabilities of their owner. The only thing that should take care of all without exception - is the compliance angle. For each region, this angle will be his, and it is directly dependent on latitude.

The table shows the optimal recommendations. And if the angle is not planned to be changed in the course of the year, you can just follow her data. Change this setting at least 2 times a year will help to significantly increase battery efficiency.

In winter average tilt angle must be 10 °... 15 ° above the optimum value of the summer - the same value - lower. Statistical data on solar energy in various cities You can see in FORUMHOUSE section.

conductor cross-section

In accordance with the precepts of electrical conductor is too small section may cause overheating and even burning. Too much - it's not bad, but would lead to unreasonably high increase in the cost of an autonomous system. Therefore, the problem of its creator - to find a "middle ground".

Let's start with the fact that the thicker wires should be installed in the chain that connects the battery to the inverter (by the way, the shorter will be the site, the better). This is where the big currents flow forces.

The conductors connecting the panel to the inverter and connecting the panel together, can be chosen with a small cross section. These parts of the circuit may be present a relatively high voltage, but there will always be a small current.

HeliosHouse (User FORUMHOUSE):

16 mm² do not need and do not need to 10 mm². 4 - more than enough. "Thick" wire will need only the inverter circuit, the cross section must be chosen in accordance with the current capacity.

"Thick" and "thin" - a loose concept, therefore, will not depart from the standards.

Given that aluminum conductors in the home power supply systems today use smoking, tabular data apply to copper conductive wires with PVC or rubber insulation.

Also, choosing conductors should pay attention to the recommendations of the manufacturers of inverters, controllers and other devices involved in the system.

breakers

The solar power circuit, as in any other chain powerful power source, it is necessary to put the protection against short circuits. The first machines or fuses should protect the power cables from the batteries to the inverter.

Leo2 (User FORUMHOUSE):

If it closes in the inverter, then so close to the fire. One of the requirements to the battery system - the presence of the machine or DC fuse-link at least one of the wires and as close as possible to the battery terminals.

In addition, the protection circuit is put in the battery and the controller. Nor should we neglect the protection of certain groups of consumers (DC consumers, home appliances and so on. D.). But this is a rule of construction of any power supply system.

Machine installed between the battery and the controller must have a large supply current misfire. In other words, the protection should fail by chance (when the load increases). Reason: when fed to the controller input voltage (Sa), then at this time the battery can not be disconnected from it. This can lead to failure of the device.

how to connect

electrical circuit assembly in the following order:

• Connecting the controller to the battery.
• Connection to the controller of solar panels.
• Connection to the controller group DC consumers.
• Connecting the inverter to the batteries.
• Connecting the load to the inverter output.

A similar sequence of connection will help protect the controller and the inverter from damage.

The controller can not turn off the load if its input at that point is energized. Since the inverter is somewhat different situation: the device is not recommended to include in the job if his output is already connected load.

Max94 (User FORUMHOUSE):

Before switching on the inverter she must be disconnected from its output all the AC loads.

Learn more about how about the peculiarities of the construction of an autonomous power supply systems you can learn from the participants of our portal by visiting the appropriate topic. Those who are seriously interested in Topic construction home solar powerWe recommend a visit to another useful section devoted to the exchange of experience in this field. In conclusion, we offer you the video of that talk about how to correctly install and connect the solar panels.

Discuss the article and read other materials devoted to country life you can on the websiteFORUMHOUSE.

Subscribe to the channel so as not to miss the next release!