Solar panels with their own hands. Calculation and selection of solar cells.

Solar cells are rarely considered as the sole source of power, however, appropriate for their installation is. So, in cloudless weather correctly calculated stand-alone system can provide electricity for electrical appliances connected to it almost all day and night. However, well-Packaged solar panels, batteries and accessories, even on a cloudy winter day will significantly reduce the cost of electricity bills on the counter.

BOB691774 (FORUMHOUSE User):

I am using solar panels from the elements already 2nd year. Was forced, as in co-op, where my garage, a very long time without electricity. Sobral 2 pcs. 60 watts, controller bought and inverter 1500 watts. Full independence simply inspires. And the light is, and work with hand tools is a pleasure.

Proper organization of autonomous power systems based on solar panels - is a science, but based on the experience of our site users, we may consider the general principles of creation.

What is a solar battery

The solar battery (SB) consists of several photovoltaic modules combined into one device by means of electrical conductors.

And if the battery is made up of modules (which are also called panels), each module is formed of a number of solar cells (called cells). Solar cell is a key element, which is at the basis of whole cells and solar installations.

The picture shows the solar cell in different formats.

But photovoltaic panel assembly.

In practice, the photovoltaic elements used in conjunction with additional equipment, which serves to convert the current to its accumulation and subsequent distribution of between consumers. The complete home solar power plant includes the following devices:

• Photovoltaic panels - the main element of the system that generates electricity when struck by sunlight.
• Battery - electric drive, allowing users to provide alternative electricity even during hours when the Security Council did not produce (eg at night).
• The controller - a device that is responsible for the timely charging of batteries, while protecting the batteries from overcharging and deep discharge.
• Inverter - converter of electrical energy, which yields the output alternating current with the required frequency and voltage.

Schematically, the power supply system, powered by a solar cell is as follows.

The circuit is quite simple, but in order for it to work effectively, it is necessary to calculate the operating parameters of all involved in its devices.

Calculation of photovoltaic panels

The first thing you need to know about to expect the construction of photovoltaic cells (panels FEP) is the amount of electricity that will consume the equipment connected to the sun batteries. Summing nominal capacity of future consumers of solar energy, which is measured in watts (W or kW), we can derive the average monthly rate of electricity consumption - Wh (kWh). A solar battery required power (W) is determined based on the obtained values.

Calculating the total power consumption should take into account not only the face value of electrical appliances, but the average daily operating time of each device.

For example, consider the list of the electrical equipment, which can provide energy for small solar power to 250 watts.

Table taken from the site of one of the manufacturers of solar panels.

There is a mismatch between the daily energy consumption - 950 Wh (0.95 kWh) and the value of solar battery power - 250 W, which in continuous operation should generate at day 6 kWh of electricity (which is much more marked needs). But since we are talking about solar panels, it should be remembered that its nameplate capacity of these device capable of developing only in the daytime (from about 9 to 16 hours), and then a clear day. In cloudy weather, electricity production also drops significantly. In the morning and in the evening the amount of electricity generated by the battery is not more than 20-30% of the daily average. In addition, the rated power can only be obtained from each cell in the presence of optimum conditions for this.

tran13 (FORUMHOUSE User):

Why nominal 60 watt battery, and it produces 30? The value of 60 W manufacturers cells fixed with insolation 1000W / m² and a battery temperature - 25 degrees. Such conditions on the ground, especially in central Russia, no.

All this is taken into account when a certain stock is put into the design of the power of solar panels.

Now let's talk about where the power rating took - 250 kW. Said parameter includes all amendments to the unevenness of the solar radiation and represents averaged data based on practical experiments. Namely, the measurement of power at various operating conditions of batteries and calculating its average daily values.

Leo2 (User FORUMHOUSE):

When learn consumption, select photoelectric elements, based on the required power modules: modules generate every 100W 400-500 Wh per day.

Go ahead: knowing the average daily demand for electricity, it is possible to calculate the required capacity of solar cells and the number of workers in a photovoltaic panel.

For a more precise definition of electricity needs to be considered not only the power of electrical appliances, but also additional losses electricity: natural loss resistance conductors as well as losses in the transformation of energy in the controller and the inverter, which depend on the efficiency of these devices.

In the implementation of further calculations we will focus on data already familiar to us the table. Thus, we assume that the total power consumption is about 1 kWh per day (0.95 kWh). As we already know, we need a solar battery having a nominal capacity - not less than 250 watts.

Suppose that, for assembly work modules you plan to use a photovoltaic cell with a nominal capacity - 1.75 W (power of each cell is determined by the product of current and voltage, which generates a sunny element). Power 144's cells are grouped in four standard modules (36 cells each) will be equal to 252 watts. On average, such a battery, we obtain 1 - 1.26 kWh of electricity per day, or 30 - 38 kWh per month. But it is on fine summer days, even in winter, these values ​​can not always get far. In this case the result can be somewhat lower, and in the southern latitudes in the northern - above.

Baracud (User FORUMHOUSE):

There are solar panels - 3.45 kW. Working in parallel with the network, so efficiency - maximum possible:

• June 467kVt * h.
• July 480 kWh.
• August 497 kWh.
• September 329 kWh.
• Oct. 305 kWh.
• November 320 kWh.
• December 216 kWh.
• January 2014 until 126 kWh.

These data are a little above average, t. To. The sun was more than usual. If the cyclone is prolonged, the production in the winter months can not exceed 100-150 kWh.

The values ​​presented - it kilowatts, which can be obtained directly from the solar panels. How much energy will reach the end-users - it depends on the optional equipment features, built-in power supply system. On them will be discussed later.

As can be seen, the number of solar cells required to generate a given power, it can only be calculated approximately. For more accurate calculations, it is recommended to use special programs and online calculators solar energyWhich will help determine the required battery power, depending on many factors (including, and the geographical position of your site).

Whatever happened final value of the recommended power, you should always have a supply of it. Indeed, over time electrical characteristics of the solar cell is reduced (the battery is getting old). Over 25 years of operation, the average loss of power of solar panels is 20%.

If you can not make a correct calculation of photovoltaic panels on the first try (and non-professionals often face the same problem), it does not matter. Missing power can always be replenished, by setting some additional photocells.

Voltage and current at the output of the panels must match the controller to be connected to them. It is necessary to provide at the stage of the calculation of the solar power plant.

Varieties of photovoltaic cells

With the help of this chapter we will try to dispel misconceptions regarding the advantages and disadvantages of the most common photovoltaic cells. This will simplify your choice of suitable devices. Widespread today received monocrystalline and polycrystalline silicon modules for solar panels.

It looks like a standard solar cell (cell) single crystal module which can be accurately distinguished by the chamfered corners.

Below is a photo of the polycrystalline cell.

Which module is better? Members actively FORUMHOUSE argue about it. Someone thinks that polycrystalline modules operate more efficiently in cloudy weather, the monocrystalline panels demonstrate excellent performance on sunny days.

Gaara (User FORUMHOUSE):

I have mono - 175 Watt gives the sun for 230 watts. But I refuse them and turn on polycrystals. Because, when the sky is clear, though electricity zaleysya any crystal, but when cloudy - mine did not work.

In this case, there will always be opponents who, after conducting practical measurements completely refute the allegations.

Votszyao (User FORUMHOUSE):

I get all the way around: polycrystalline very sensitive to darkening. It should be a small cloud to pass by the sun, as it is immediately reflected on the amount of generated current. Voltage, by the way, virtually unchanged. Microcrystalline same panel behaves more stably. In good light, both panels are very good: the stated capacity of the two panels - 50W, 50W, both these same issue. Hence we see how disappears myth that monopanels provide more power in a good light.

The second statement refers to the life of the photovoltaic elements, polycrystalline monocrystalline cells age faster. Consider the data of the official statistics: the standard service life monocrystalline panels is 30 years (some manufacturers claim that these modules can be operated up to 50 years). At the same time efficient operation of polycrystalline panels does not exceed 20 years.

Indeed, solar power (even with very high quality) to operate each year is reduced by a certain fraction of a percent (0.67% - 0.71%). In the first year of operation of power can be reduced immediately to 2% and 3% (v monocrystalline and polycrystalline panels - respectively). As you can see, there is a difference, but it is insignificant. And when you consider that the presented figures largely depend on the quality of PV modules, the difference can and does not take into account. Especially, there are cases where cheap monocrystalline panels made careless producers lost 20% of its capacity in the first year of operation. Conclusion: the more reliable manufacturer of photovoltaic modules, more durable its products.

Many users of our portal claim that monocrystalline modules are always more expensive than polycrystalline. Most manufacturers of the difference in price (per one watt of power generated) actually palpable, making the purchase of polycrystalline cells more attractive. I argue this is impossible, but you can not argue with the fact that the efficiency of monocrystalline panels is higher than that of polycrystalline. Consequently, for the same power of work modules polycrystalline battery will have a large area. In other words, the winning price, buyer polycrystalline cells may play in the area, that with a lack of space for the installation of the Security Council may deprive it so obvious at first glance benefits.

Captain Deadly (User FORUMHOUSE):

In common monocrystals efficiency of, on average, equal to 17% -18% of poly - about 15%. Difference - 2% -3%. However, the area of ​​the difference is - 12% -17%. Since amorphous panels difference is even more evident: in their efficiency - 10.8% single crystal panel may be square in half amorphous.

Amorphous panel - this is another kind of photovoltaic cells, which are not yet managed to become quite popular, despite its obvious advantages: low backoff when the temperature rises, the ability to generate electricity even under low light conditions, the relative cheapness of power produced kW etc. And one of the reasons for the low popularity lies in their very limited efficiency. Amorphous modules are called flexible modules. Flexible structure greatly facilitates installation, removal and storage.

Jabber (User FORUMHOUSE):

I do not know who it is amorphous advertises. Efficiency of their low, place almost twice as much occupied, and the age-efficiency, as well as that of the crystal is reduced. Classical modules are designed for 25 years of service with the loss of efficiency of 20%. Plus amorphous until only one: look like black glass (you can cover the entire facade of such).

Choosing the operating elements for the construction of solar panels in the first place should be guided by the reputation of the manufacturer. After all, it depends on the quality of their actual performance. You also can not lose sight of the conditions under which will be the installation of solar modules: if surface area available for the installation of solar panels, you have limited, it is advisable to use single crystals. If the lack of free space there, then pay attention to polycrystalline or amorphous panels. The latter may even be more practical than crystalline panels.

Another advantage of amorphous panels to crystalline panels is that their elements can be mounted directly to the window openings (in place of conventional glass), or even to use them for decoration facades.

By purchasing ready-made panels from the manufacturer, you can greatly simplify your task to build solar panels. For those who prefer to create everything with their own hands, the manufacture of solar modules, the process will be described in the continuation of this article. Also in the near future we are going to talk about that, you should choose the battery according to what criteria, controllers and inverters - devices, without which none of the solar cell can not function fully. Stay tuned for our tape his articles.

The picture shows two panels: the self-made monocrystalline at 180W (left) and on polycrystalline 100W manufacturer (right).

About the most popular alternative energy sources you can find in the relevant subject open to discussion on our portal. The section on construction of an autonomous houseYou can learn a lot about alternative energy and solar in particular. A short video clip will tell the basic elements of a standard solar power and about the features of the installation of solar panels.

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

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