High power solar panels. Solar batteries for the garden and home: types, principles of operation and procedure for calculating solar systems

Solar panels are a popular source of cheap electricity in many countries. Using natural resources, man has learned to produce electricity not only from water, wind flows and the combustion of minerals, but also from the sun's rays. It is worth understanding that solar panels are part of the system; on their own, they will not generate useful electrical current. Let's figure out what types of solar panels are available and whether they are worth installing.

Solar batteries began their development back in the 19th century. The prerequisite for this was revolutionary research on the transformation of solar energy into a more material component.

The first solar panels had only 1%, and their chemical basis was selenium. The first contributions to the development of such batteries were made by A. Becquerel, W. Smith, and C. Fritts.

But using only 1% of the total energy supplied to the solar panel is very little. These elements could not provide uninterrupted power supply to the equipment, so research continued.

In 1954, three scientists - Gordon Pearson, Darryl Chapin and Cal Fuller - invented a battery with an efficiency of 4%. It worked on silicon, and subsequently its efficiency was increased to 20%.

Currently, solar panels produce only 1% of the world's energy. They are mainly carried out to places that are difficult to reach for electrification. This power source is widely used in the space industry. Experts believe that all paths are open to such a battery, since solar activity is increasing every year.

In our latitudes, these batteries are installed in private homes to save energy consumption and care for the environment.

Pros and cons of solar panels

A solar battery has its advantages and disadvantages. Let's look at them in more detail.

Pros:

• Highly environmentally friendly. During operation, no irreplaceable minerals are used and no waste is generated.
• No noise.
• Availability. Every corner of the globe is illuminated by the Sun.
• Consistency. If fossils can run out and their production decrease, then there is no need to worry about solar energy. According to scientists, nothing threatens our star for a long time.
• Wide range of uses. The panels can be used both in rural areas and in space.
• New technologies. Tests are being carried out on solar panels, huge amounts of money are being spent on their improvement, this area is constantly being modernized and undergoing innovation.

Minuses:

• Expensive. Not every person can afford to install enough solar cells to meet their needs. Electrification of a small country house will cost $1,000-1,200, while a two-story mansion can cost up to $10,000.
• Solar illumination is a variable unit. Battery efficiency will decrease at night and in cloudy weather.

Battery contents

A lot of people have the wrong idea about solar panels. After all, the roof panel itself cannot provide alternating current.

To provide your home with electricity, you will have to purchase:

1. Actually solar panels. This is the structural element that is attached to the walls or roof of the house. When a quantum of sunlight hits the silicon crystals, they begin to vibrate and an electric current is created.
2. . The energy that is not used for household consumption is accumulated in this device, and then at night or in inclement weather it is consumed.
3. voltage. This element is not mandatory, but desirable. It increases the battery life, reports its extremely low and high charge.
4. , or energy converter. In a battery, the electric current is constant, but for domestic needs an alternating current is required. The inventory manager performs this transformation.

As we can see, solar panels are only a small part of the system. They themselves consist of smaller elements - modules. Since the device of these batteries is modular, if necessary, by connecting components you can add panels or remove unnecessary ones.

Types of solar panels

A solar panel consists of components, and they can be different:

• polycrystalline;
• film.

In the first case, one photocell is one silicon crystal. These batteries have the highest efficiency (up to 25%), but they are very expensive. The plates are deep blue in color and their edges are slightly rounded.

Polycrystalline solar cells combine several silicon crystals. They are widespread, their efficiency fluctuates around 20-23%. The structure is heterogeneous, and they absorb sunlight worse than monocrystalline panels. They are more affordable in price.

Thin-film (amorphous) photocells involve sputtering a semiconductor onto a substrate. The main advantage is that they can be placed on literally any surface, they are flexible. The disadvantage is low performance.

According to the technical principle, electrification with solar cells is divided into:

• open systems;
• closed systems (autonomous);
• combined.

An open system is called when the solar panel is connected to the general power grid. In this case, there is no need to purchase a battery and a controller. Solar panels are connected to the general network using an inverter. If the power consumed by household appliances does not exceed that produced by the panels, then no current is taken from the general electrical network. In the case when you turn on high-power devices and the batteries cannot supply them with current, electricity is taken from the general network. The peculiarity is that if there is no current in the main network, the batteries will not work.

With autonomous systems, everything is clear: they are closed and do not require an external network. Energy is stored in the battery and used as needed.

Combined networks are not widely used because they are expensive. The complex design combines the type of open and closed system. If there is excess electricity generated by batteries, it can be redirected to the general grid.

Application of solar panels

In addition to astronautics and providing private homes with electricity, solar panels or batteries are used in the following areas:

• Automotive industry. Eco-friendly transport is gaining popularity, because gasoline and gas emissions pollute the atmosphere, and fuel prices are constantly rising. Solar-powered cars can reach speeds of up to 140 km/h.
• Operation of water transport (barges, boats, yachts). Such transport can be found in Turkey. The boats develop a low speed (up to 10 km/h), and this allows tourists to explore the sights and magnificent landscapes of this country.
• Energy supply of buildings. In developed European countries, many municipal buildings and structures fully meet their needs using the energy generated by solar panels.
• Aircraft manufacturing. Thanks to the presence of batteries, the aircraft can not consume fuel for a long time in flight.

The industry is constantly evolving. Chargers for phones and laptops powered by solar energy have already been invented.

What to look for when buying solar panels for your home

This information will be useful if you decide to switch to a solar energy source. When purchasing all the components for such a system, you need to know where you can save money and what to pay special attention to:

1. Buy components (panels, battery, inverter) late winter-early spring . As a rule, stores offer big discounts at this time.
2. Don't buy too many solar panels at once. Remember that this system is modular, and it is very easy to get the required quantity to meet the needs of household appliances.
3. Preferably replace all lamps incandescent in the house to LED or LED . They consume less energy and have a longer service life.
4. For your home, buy from solar batteries with an output voltage of 12 V . These are the values ​​that are suitable for household appliances; very few devices use 24 V and 48 V. You can find all voltage indicators in the device datasheet.

When choosing solar panels, please note that each one must be placed in a protective aluminum housing. This metal is lightweight, durable, and corrosion resistant. The protective glass on top should be matte, without any gloss or glare.

It is quite possible to provide your home with comfort, warmth and not pay for electricity. To do this, you need to install such a power supply system. But it is worth considering that it also requires significant investments and has a number of nuances. After studying all the positive and negative aspects, we hope that you will make the right choice.

The sun is an inexhaustible source of energy. It can be used by burning trees or heating water in solar heaters, converting the resulting heat into electricity. But there are devices that convert sunlight into electricity directly. These are solar panels.

Scope of application

There are three areas for using solar energy:

• Energy saving. Solar panels allow you to abandon centralized power supply or reduce its consumption, as well as sell excess electricity to the power supply company.
• Providing electricity to facilities to which connecting power lines is impossible or economically unprofitable. This could be a summer cottage or a hunting lodge located far from power lines. Such devices are also used to power lamps in remote areas of the garden or bus stops.
• Power supply for mobile and portable devices. When hiking, fishing trips and other similar activities, there is a need to charge phones, cameras and other gadgets. Solar cells are also used for this.

Solar panels are convenient to use where electricity cannot be supplied

Principle of operation

Solar cell elements are silicon wafers 0.3 mm thick. On the side where the light hits, boron is added to the plate. This leads to the appearance of an excess number of free electrons. Phosphorus is added to the reverse side, which leads to the formation of “holes”. The boundary between them is called a p-n junction. When light hits the plate, it “knocks out” electrons onto the back side. This is how a potential difference appears. Regardless of the size of the element, one cell develops a voltage of 0.7 V. To increase the voltage, they are connected in series, and to increase the current - in parallel.

Expert opinion

Alexey Bartosh

Specialist in repair and maintenance of electrical equipment and industrial electronics.

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In some designs, to increase power, lenses were installed above the elements or a system of mirrors was used. With the decreasing cost of batteries, such devices have become obsolete.

The maximum efficiency of the panel, and therefore the power, is achieved when the light falls at an angle of 90 degrees. In some stationary devices, the battery rotates to follow the sun, but this greatly increases the cost and makes the design heavier.

The principle of operation of a solar battery

Advantages and disadvantages of using batteries

Solar panels, like any device, have advantages and disadvantages related to the principle of operation and design features.

Advantages of solar panels:

• Autonomy. Allows you to provide electricity to remote buildings or lamps and the operation of mobile devices in field conditions.
• Economical. The light from the sun is used to generate electricity, for which you do not have to pay. Therefore, PV systems (photovoltaic systems) pay for themselves in 10 years, which is less than the service life of more than 30. Moreover, 25–30 years is the warranty period, and the photovoltaic plant will continue to operate after that, bringing profit to the owner. Of course, it is necessary to take into account the periodic replacement of inverters and batteries, but still, using such a power plant helps save money.
• Environmental friendliness. During operation, the devices do not pollute the environment and do not make noise, unlike power plants operating on other types of fuel.

In addition to its advantages, FES has disadvantages:

• High price. Such a system is quite expensive, especially considering the price of batteries and inverters.
• Long payback period. The funds invested in a photovoltaic power plant will pay off only after 10 years. This is more than the bulk of other investments.
• Photovoltaic systems take up a lot of space - the entire roof and walls of a building. This violates the design of the structure. In addition, high-capacity batteries take up an entire room.
• Uneven power generation. The power of the device depends on the weather and time of day. This is compensated by installing batteries or connecting the system to the network. This allows you to sell excess electricity to the electric company during the day during the day, and at night, on the contrary, connect the equipment to the centralized power supply.

Technical specifications: what to look for

The main parameter of a photocell system is power. The voltage of such an installation reaches its maximum in bright light and depends on the number of elements connected in series, which in almost all designs is 36. The power depends on the area of ​​one element and the number of chains of 36 pieces connected in parallel.

In addition to the batteries themselves, it is important to choose a battery charging controller and an inverter that converts the battery charge into mains voltage, as well as the panels themselves.

Batteries have a permissible charging current that cannot be exceeded, otherwise the system will fail. Knowing the battery voltage, it is easy to determine the power required for charging. It must be greater than the power of the solar power plant, otherwise on a sunny day part of the energy will be unused.

The controller provides charge to the batteries and must also have the power to fully utilize the sun's energy.

Equipment that receives energy from the solar power plant is connected to the inverter, so its power must correspond to the total power of electrical appliances.

Types of solar panels

In addition to size and power, the panels differ in the way the individual elements are made from silicon.

Appearance of mono- and polycrystalline panels

Monocrystalline silicon elements

Solar cell cells, made of monocrystalline silicon, are shaped like a square with rounded corners. This is due to manufacturing technology:

• a cylindrical crystal is grown from molten silicon of a high degree of purity;
• after cooling, the edges of the cylinder are cut off, and the circle base takes the shape of a square with rounded corners;
• the resulting block is cut into plates 0.3 mm thick;
• boron and phosphorus are added to the plates and contact strips are glued to them;
• A battery cell is assembled from ready-made elements.

The finished cell is fixed to the base and covered with glass that transmits ultraviolet rays or laminated.

Such devices are characterized by the highest efficiency and reliability, therefore they are installed in important places, for example, in spacecraft.

Multi-polycrystalline silicon photocells

In addition to solid crystal elements, there are devices in which solar cells are made of polycrystalline silicon. The production technology is similar. The main difference is that instead of a round crystal, a rectangular block is used, consisting of a large number of small crystals of various shapes and sizes. Therefore, the elements are rectangular or square in shape.

Waste from the production of microcircuits and photocells is taken as raw material. This reduces the cost of the finished product, but degrades its quality. Such devices have lower efficiency - on average 18% versus 20–22% for monocrystalline batteries. However, the question of choice is quite complex. For different manufacturers, the price of one kilowatt of power for monocrystalline and polycrystalline panels can be the same or in favor of any type of device.

Amorphous silicon photocells

In recent years, flexible batteries, which are lighter than rigid ones, have become widespread. Their manufacturing technology differs from the manufacturing technology of mono- and polycrystalline panels - thin layers of silicon with additives are sprayed onto a flexible base, usually a steel sheet, until the required thickness is achieved. After this, the sheets are cut, conductive strips are glued to them, and the entire structure is laminated.

Amorphous silicon solar cells

The efficiency of such batteries is approximately 2 times less than that of rigid structures, however, they are lighter and more durable due to the fact that they can be bent.

Such devices are more expensive than conventional ones, but there is no alternative to them in camping conditions, when lightness and reliability are of primary importance. The panels can be sewn onto a tent or backpack and charge the batteries while moving. When folded, such devices resemble a book or a rolled-up drawing that can be placed in a case resembling a tube.

In addition to charging mobile devices on the go, flexible panels are installed in electric cars and electric planes. On the roof, such devices follow the curves of the tiles, and if glass is used as a base, it takes on a tinted appearance and can be inserted into a house window or greenhouse.

Charge controller for solar panels

Direct connection of the panel to the battery has disadvantages:

• A battery with a nominal voltage of 12 V will only charge when the voltage at the output of the photocells reaches 14.4 V, which is close to the maximum. This means that part of the time the batteries will not be charged.
• The maximum voltage of photocells is 18 V. At this voltage, the battery charging current will be too high, and they will quickly fail.

In order to avoid these problems, it is necessary to install a charge controller. The most common designs are PWM and MPRT.

PWM charge controller

The operation of the PWM controller (pulse-width modulation - PWM) maintains a constant output voltage. This ensures maximum battery charge and protects it from overheating during charging.

MPPT charge controller

The MPPT controller (Maximum power point tracker) provides an output voltage and current value that allows maximum use of the potential of the solar battery, regardless of the brightness of sunlight. When the light brightness is reduced, it raises the output voltage to the level necessary to charge the batteries.

Such a system is found in all modern inverters and charging controllers

Types of batteries used in batteries

Different types of batteries that can be used for a solar panel

Batteries are an important element of the 24-hour solar power supply system for a home.

The following types of batteries are used in such devices:

• starter;
• gel;
• AGM batteries;
• flooded (OPZS) and sealed (OPZV) batteries.

Other types of batteries, such as alkaline or lithium, are expensive and rarely used.

All these types of devices must operate at temperatures from +15 to +30 degrees.

Starter batteries

The most common type of battery. They are cheap, but have a high self-discharge current. Therefore, after a few cloudy days, the batteries will be discharged even without load.

The disadvantage of such devices is that gas is released during operation. Therefore, they must be installed in a non-residential, well-ventilated area.

In addition, the service life of such batteries is up to 1.5 years, especially with multiple charge-discharge cycles. Therefore, in the long run, these devices will be the most expensive.

Gel batteries

Gel batteries are maintenance-free products. There is no gas emission during operation, so they can be installed in living rooms and rooms without ventilation.

Such devices provide high output current, have high capacitance and low self-discharge current.

The disadvantage of such devices is their high price and short service life.

AGM batteries

These batteries have a short service life, however, they have many advantages:

• no gas emission during operation;
• small in size;
• a large number (about 600) charge-discharge cycles;
• fast (up to 8 hours) charge;
• works well even when not fully charged.

AGM battery from inside

Flooded (OPZS) and sealed (OPZV) batteries

Such devices are the most reliable and have the longest service life. They have a low self-discharge current and high energy capacity.

These qualities make such devices the most popular for installation in photocell systems.

How to determine the size and number of photocells?

The required size and number of photocells depends on the voltage, current and power to be drawn from the battery. The voltage of one element on a sunny day is 0.5 V. When it is cloudy it is much lower. Therefore, to charge 12 V batteries, 36 photocells are connected in series. Accordingly, 24 V batteries require 72 cells, and so on. Their total number depends on the area of ​​one element and the required power.

One square meter of battery area, taking into account efficiency, can produce approximately 150 W. More precisely, it can be determined from meteorological reference books showing the amount of solar radiation at the installation site of a solar power plant or on the Internet. The efficiency of the device is indicated in the passport.

When making photovoltaics with your own hands, the required number of elements is determined by the power of one element in a given climate, taking into account the efficiency.

The calculation of the number of solar panels is based on the required electricity

Efficiency of solar panels in winter

Despite the fact that the sun rises lower in winter, the flow of light decreases slightly, especially after snow falls.

There are three main reasons why solar cells are less efficient in winter:

• The angle of incidence of the rays changes. In order to maintain power, the angle of the battery must be changed at least once a season, and preferably every month.
• Snow, especially wet snow, sticks to the surface of the device. It must be removed immediately after falling out.
• In winter, there is less daylight hours and more cloudy days. It is impossible to change this, so you have to calculate the battery power based on the winter minimum.

Installation Rules

The maximum power of the panel is achieved in a position in which the sun's rays fall perpendicularly. This must be taken into account during installation. It is also important to consider what time of day the cloudiness is minimal. If the angle of the roof and its position do not meet the requirements, it can be corrected by adjusting the base.

There should be an air gap of 15–20 centimeters between the battery and the roof. This is necessary to allow rain to flow through and to prevent overheating.

Photovoltaic cells do not perform well in the shade, so you should avoid placing them in the shade of buildings or trees.

Power plants made from solar photocells are a promising environmentally friendly source of energy. Their widespread use will solve problems with energy shortages, environmental pollution and the greenhouse effect.

Now you will learn something that solar panel sellers will never tell you.

Exactly a year ago, in October 2015, as an experiment, I decided to join the ranks of the “greens” who are saving our planet from premature death, and purchased solar panels with a maximum power of 200 watts and a grid inverter designed for a maximum of 300 (500) watts of generated power . In the photo you can see the structure of the polycrystalline 200 watt panel, but a couple of days after purchase it became clear that in a single configuration it was too low voltage, not enough for the correct operation of my grid inverter.

So I had to change it to two 100-watt monocrystalline panels. In theory they should be a little more efficient, but in reality they are just more expensive. These are high quality panels from the Russian brand Sunways. I paid 14,800 rubles for two panels.

The second cost item is a Chinese-made grid inverter. The manufacturer did not identify itself in any way, but the device was made with high quality, and an opening showed that the internal components are designed for a power of up to 500 watts (instead of 300 written on the case). Such a grid costs only 5,000 rubles. The grid is an ingenious device. On the one hand, + and - from the solar panels are connected to it, and on the other hand, it is connected to absolutely any electrical outlet in your home using a regular electrical plug. During operation, the grid adapts to the frequency in the network and begins to “pump” alternating current (converted from direct current) into your 220 volt home network.

The grid operates only when there is voltage in the network and cannot be considered as a backup power source. This is its only drawback. And a huge advantage of a grid inverter is that you basically don’t need batteries. After all, batteries are the weakest link in alternative energy. If the same solar panel is guaranteed to work for more than 25 years (that is, after 25 years it will lose approximately 20% of its performance), then the service life of an ordinary lead-acid battery under similar conditions will be 3-4 years. Gel and AGM batteries will last longer, up to 10 years, but they also cost 5 times more than conventional batteries.

Since I have mains electricity, I don't need any batteries. If you make the system autonomous, then you need to add another 15-20 thousand rubles to the budget for the battery and the controller for it.

Now, as for electricity generation. All energy generated by solar panels enters the network in real time. If there are consumers of this energy in the house, then all of it will be used up, and the meter at the entrance to the house will not “spin”. If the instantaneous generation of electricity exceeds that currently consumed, then all the energy will be transferred back to the network. That is, the counter will “spin” in the opposite direction. But there are nuances here.

Firstly, many modern electronic meters count the current passing through them without taking into account its direction (that is, you will pay for the electricity sent back to the network). And secondly, Russian legislation does not allow private individuals to sell electricity. This is allowed in Europe and that is why every second house there is covered with solar panels, which, combined with high network tariffs, allows you to really save money.

What to do in Russia? Do not install solar panels that can produce more energy than the current daily energy consumption in the house. It is for this reason that I have only two panels with a total power of 200 watts, which, taking into account inverter losses, can supply approximately 160-170 watts to the network. And my house consistently consumes about 130-150 watts per hour around the clock. That is, all the energy generated by solar panels will be guaranteed to be consumed inside the house.

To control the energy produced and consumed, I use Smappee. I already wrote about him last year. It has two current transformers, which allow you to keep track of both the network electricity and the electricity generated by solar panels.

Let's start with theory and move on to practice.

There are many solar power calculators on the Internet. From my initial data, according to the calculator, it follows that the average annual electricity generation of my solar panels will be 0.66 kWh/day, and the total production for the year will be 239.9 kWh.

This data is for ideal weather conditions and does not take into account losses for converting direct current to alternating current (you are not going to convert your household's power supply to direct voltage?). In reality, the resulting figure can be safely divided by two.

Let’s compare with actual production data for the year:

2015 - 5.84 kWh
October - 2.96 kWh (from October 10)
November - 1.5 kWh
December - 1.38 kWh
2016 - 111.7 kWh
January - 0.75 kWh
February - 5.28 kWh
March - 8.61 kWh
April - 14 kWh
May - 19.74 kWh
June - 19.4 kWh
July - 17.1 kWh
August - 17.53 kWh
September - 7.52 kWh
October - 1.81 kWh (until October 10)

Total: 117.5 kWh

Here is a graph of electricity generation and consumption in a country house over the last 6 months (April-October 2016). It was during April-August that the lion's share (more than 70%) of electrical energy was generated by solar panels. During the remaining months of the year, production was impossible mainly due to cloudiness and snow. Well, don’t forget that the efficiency of the grid for converting direct current into alternating current is approximately 60-65%.

Solar panels are installed in almost ideal conditions. The direction is strictly south, there are no tall buildings nearby that cast a shadow, the installation angle relative to the horizon is exactly 45 degrees. This angle will give the maximum average annual electricity production. Of course, it was possible to buy a rotary mechanism with an electric drive and a sun tracking function, but this would increase the budget of the entire installation by almost 2 times, thereby pushing back its payback period to infinity.

I have no questions about generating solar energy on sunny days. It fully corresponds to the calculated ones. And even a decrease in production in winter, when the sun does not rise high above the horizon, would not be so critical if not for... cloudiness. Cloudiness is the main enemy of photovoltaics. Here is the hourly output for two days: October 5 and 6, 2016. On October 5 the sun was shining, and on October 6 the sky was covered with lead clouds. Sun, oh! Where are you hiding?

In winter there is another small problem - snow. There is only one way to solve this: install the panels almost vertically. Or manually clear them of snow every day. But snow is nonsense, the main thing is that the sun is shining. Even if it’s low above the horizon.

So, let's calculate the costs:

Grid inverter (300-500 watts) - 5,000 rubles
Monocrystalline solar panel (Grade A - highest quality) 2 pcs, 100 watts each - 14,800 rubles
Wires for connecting solar panels (cross section 6 mm2) - 700 rubles
Total: 20,500 rubles.
Over the past reporting period, 117.5 kWh were generated; at the current daily tariff (5.53 rubles/kWh), this will amount to 650 rubles.
If we assume that the cost of network tariffs will not change (in fact, they change upward 2 times a year), then I will be able to return my investments in alternative energy only in 32 years!

And if you add batteries, then this whole system will never pay for itself. Therefore, solar energy in the presence of grid electricity can be beneficial only in one case - when our electricity costs the same as in Europe. If 1 kWh of network electricity costs more than 25 rubles, then solar panels will be very profitable.
In the meantime, it is profitable to use solar panels only where there is no network electricity, and its implementation is too expensive. Let's assume that you have his country house, located 3-5 km from the nearest electric line. Moreover, it is high-voltage (that is, you will need to install a transformer), and you have no neighbors (no one to share the costs with). That is, you will have to pay approximately 500,000 rubles to connect to the network, and after that you will also have to pay network tariffs. In this case, it will be more profitable for you to buy solar panels, a controller and batteries for this amount - after all, after putting the system into operation, you will no longer need to pay any more.
In the meantime, it is worth considering photovoltaics exclusively as a hobby.

Solar panels are rarely considered as the only source of electricity, however, there is a rationale for installing them. Thus, in cloudless weather, a properly designed autonomous system will be able to provide electrical appliances connected to it with electricity almost around the clock. However, well-equipped solar panels, batteries and auxiliary devices, even on a cloudy winter day, will significantly reduce the cost of paying for electricity by the meter.

BOB691774 User FORUMHOUSE

I have been using solar panels from elements for the 2nd year now. I was forced to, because in the cooperative where my garage was, the power was turned off for a very long time. Collected 2 pieces. 60 watts each, I bought a controller and a 1500 watt inverter. Complete independence is simply inspiring. And there is light, and working with hand tools is a pleasure.

The correct organization of autonomous power supply systems based on solar panels is a whole science, but based on the experience of users of our portal, we can consider the general principles of their creation.

What is a solar battery

A solar battery (SB) is several photovoltaic modules combined into one device using electrical conductors.

And if the battery consists of modules (which are also called panels), then each module is formed from several solar cells (which are called cells). The solar cell is the key element that is at the heart of batteries and entire solar systems.

The photo shows solar cells of various formats.

Here is the assembled photovoltaic panel.

In practice, photovoltaic cells are used in conjunction with additional equipment that serves to convert current, for its accumulation and subsequent distribution among consumers. The home solar power station kit includes the following devices:

1. Photovoltaic panels are the main element of the system, generating electricity when sunlight hits it.
2. A rechargeable battery is an energy storage device that allows you to provide consumers with alternative electricity even during those hours when the solar system does not generate it (for example, at night).
3. The controller is a device responsible for timely recharging of batteries, while simultaneously protecting the batteries from overcharging and deep discharge.
4. An inverter is an electrical energy converter that allows you to produce alternating current at the output with the required frequency and voltage.

Schematically, a power supply system powered by solar panels looks like this.

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

Calculation of photovoltaic panels

The first thing you need to know when planning to calculate the design of photovoltaic converters (PV panels) is the amount of electricity that the equipment connected to the solar panels will consume. By summing up the rated power of future solar energy consumers, which is measured in Watts (W or kW), we can derive the average monthly rate of electricity consumption - Wh (kWh). And the required power of the solar battery (W) will be determined based on the obtained value.

When calculating the total power consumption, you should take into account not only the rating of electrical appliances, but also the average daily operating time of each device.

For example, consider a list of electrical equipment that a small solar power plant with a capacity of 250 W can provide energy.

The table was taken from the website of one of the solar panel manufacturers.

There is a discrepancy between the daily electricity consumption - 950 Wh (0.95 kWh) and the power value of the solar battery - 250 W, which, during continuous operation, should generate 6 kWh of electricity per day (which is much more than the indicated needs). But since we are talking specifically about solar panels, we should remember that these devices are capable of developing their rated power only during daylight hours (from about 9 a.m. to 4 p.m.), and even then on a clear day. In cloudy weather, electricity production also drops noticeably. And in the morning and evening, the volume of electricity generated by the battery does not exceed 20–30% of the daily average. In addition, the rated power can be obtained from each cell only under optimal conditions.

trans13 User FORUMHOUSE

Why is the battery rating 60 W, but it produces 30? The value of 60 W is fixed by cell manufacturers at insolation of 1000 W/m² and battery temperature of 25 degrees. There are no such conditions on earth, and especially in central Russia.

All this is taken into account when a certain power reserve is included in the design of solar panels.

Now let's talk about where the power indicator comes from - 250 kW. This parameter takes into account all corrections for the unevenness of solar radiation and represents averaged data based on practical experiments. Namely: measuring power under various battery operating conditions and calculating its average daily value.

Leo2 User FORUMHOUSE

When you know the volume of consumption, choose photovoltaic elements based on the required power of the modules: every 100W of modules generate 400-500 Wh per day.

To more accurately determine the needs for electricity, it is necessary to take into account not only the power of electrical appliances, but also additional losses of electricity: natural losses due to the resistance of conductors, as well as losses due to energy conversion in the controller and inverter, which depend on the efficiency of these devices.

When making further calculations, we will be guided by the data from the table we are already familiar with. So, let's assume that the total power consumption is approximately 1 kWh per day (0.95 kWh). As we already know, we will need a solar battery with a rated power of at least 250 W.

Let's assume that to assemble working modules you plan to use photovoltaic cells with a rated power of 1.75 W (the power of each cell is determined by the product of the current and voltage generated by the solar cell). The power of 144 cells combined into four standard modules (36 cells each) will be 252 W. On average, from such a battery we will receive 1 - 1.26 kWh of electricity per day, or 30 - 38 kWh per month. But this is on fine summer days; in winter, even these values ​​cannot always be obtained. At the same time, in northern latitudes the result may be slightly lower, and in southern latitudes – higher.

Baracud User FORUMHOUSE

There are solar panels - 3.45 kW. They work in parallel with the network, so the efficiency is the highest possible:

• June 467 kWh.
• July 480 kWh.
• August 497 kWh.
• September 329 kWh.
• October 305 kWh.
• November 320 kWh.
• December 216 kWh.
• January 2014 so far 126 kWh.

These data are slightly higher than average, because there was more sun than usual. If the cyclone is prolonged, then production in the winter month may not exceed 100-150 kWh.

The values ​​presented are the kilowatts that can be obtained directly from solar panels. How much energy will reach end consumers depends on the characteristics of additional equipment built into the power supply system. We'll talk about them later.

As we can see, the number of solar cells required to generate a given power can only be approximately calculated. For more accurate calculations, it is recommended to use special ones that will help determine the required battery power depending on many parameters (including the geographical location of your site).

Whatever the final value of the recommended power turns out to be, it is always necessary to have some reserve. After all, over time, the electrical characteristics of a solar battery decrease (the battery ages). Over 25 years of operation, the average power loss of solar panels is 20%.

If it was not possible to correctly calculate the photovoltaic panels the first time (and non-professionals very often encounter a similar problem), this is not a problem. The missing power can always be replenished by installing several additional photocells.

The voltage and current strength at the output of the panels must correspond to the parameters of the controller that will be connected to them. This must be taken into account at the stage of calculating the solar power plant.

Types 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 make it easier for you to choose the right devices. Monocrystalline and polycrystalline silicon modules for solar batteries are widely used today.

This is what a standard solar cell (cell) of a monocrystalline module looks like, which can be unmistakably distinguished by its beveled corners.

Below is a photo of a polycrystalline cell.

Which module is better? FORUMHOUSE users are active. Some people believe that polycrystalline modules work more efficiently in cloudy weather, while monocrystalline panels demonstrate excellent performance on sunny days.

Gaara User FORUMHOUSE

I have mono - 175 W is given in the sun under 230 W. But I refuse them and switch to polycrystals. Because when the sky is clear, electricity can flow from any crystal, but when it’s cloudy, mine don’t work at all.

At the same time, there will always be opponents who, after carrying out practical measurements, completely refute the presented statement.

Wojiao User FORUMHOUSE

I get the opposite: polycrystals are very sensitive to darkening. As soon as a small cloud passes across the sun, it is immediately reflected in the amount of current generated. The voltage, by the way, practically does not change. A monocrystalline panel behaves more stable. In good lighting, both panels behave very well: the declared power of both panels is 50W, both of them output 50W. From here we see how the myth that monopanels provide more power in good lighting is disappearing.

The second statement concerns the service life of photovoltaic cells: polycrystalline cells age faster than monocrystalline cells. Consider the official statistics: the standard service life of monocrystalline panels is 30 years (some manufacturers claim that such modules can last up to 50 years). At the same time, the period of effective operation of polycrystalline panels does not exceed 20 years.

Indeed, the power of solar panels (even with very high quality) decreases by certain fractions of a percent (0.67% - 0.71%) every year of operation. Moreover, in the first year of operation, their power can immediately decrease by 2% and 3% (for monocrystalline and polycrystalline panels, respectively). As you can see, there is a difference, but it is insignificant. And if we take into account that the presented indicators largely depend on the quality of photovoltaic modules, then the difference can not be taken into account at all. Moreover, there are known cases where cheap monocrystalline panels made by careless manufacturers lost up to 20% of their power in the first year of operation. Conclusion: the more reliable the manufacturer of photovoltaic modules, the more durable its products.

Many users of our portal claim that monocrystalline modules are always more expensive than polycrystalline ones. For most manufacturers, the difference in price (in terms of one watt of generated power) is actually noticeable, which makes the purchase of polycrystalline elements more attractive. You can’t argue with this, but you can’t argue with the fact that the efficiency of monocrystalline panels is higher than that of polycrystalline panels. Consequently, with the same power of working modules, polycrystalline batteries will have a larger area. In other words, while winning in price, the buyer of polycrystalline elements may lose in area, which, if there is insufficient free space for installing a solar panel, can deprive him of the benefit that is so obvious at first glance.

Captain Deadly User FORUMHOUSE

For common single crystals, the efficiency is, on average, 17%-18%, for poly - about 15%. The difference is 2%-3%. However, in terms of area this difference is 12%-17%. With amorphous panels, the difference is even more obvious: with their efficiency of 8-10%, a monocrystalline panel can be half the area of ​​an amorphous one.

Amorphous panels are another type of photovoltaic elements that have not yet become quite in demand, despite their obvious advantages: low power loss when the temperature rises, the ability to generate electricity even in very low light, the relative cheapness of one kW of energy produced, and so on. . And one of the reasons for their low popularity lies in their very limited efficiency. Amorphous modules are also called flexible modules. The flexible structure greatly facilitates their installation, dismantling and storage.

Jabber User FORUMHOUSE

When choosing working elements for the construction of solar panels, you should first of all focus on the reputation of their manufacturer. After all, their actual performance characteristics depend on quality. You should also not lose sight of the conditions under which the installation of solar modules will be carried out: if the area allocated for the installation of solar panels is limited, then it is advisable to use monocrystals. If there is no shortage of free space, then pay attention to polycrystalline or amorphous panels. The latter may be even more practical than crystalline panels.

Another advantage of amorphous panels over crystalline panels is that their elements can be installed directly in window openings (in place of conventional glass) or even used for finishing facades.

By purchasing ready-made panels from manufacturers, you can greatly simplify your task of building solar panels. For those who prefer to create everything with their own hands, the process of manufacturing solar modules will be described in the continuation of this article. Also, in the near future, we plan to talk about what criteria should be used to choose batteries, controllers and inverters - devices without which not a single solar battery can function fully. Stay tuned for updates to our article feed.

The photo shows 2 panels: a homemade monocrystalline 180W (left) and a polycrystalline 100W from the manufacturer (right).

You can find out in the corresponding topic open for discussion on our portal. In the section dedicated to, you can learn a lot of interesting things about alternative energy and solar panels, in particular. A short video will tell you about the main elements of a standard solar power plant and the features of installing solar panels.

Over the past 10 years, houses with solar panels on their roofs have gone from curiosity to commonplace.
This technology has been available for decades - astronauts have been using solar-powered satellites since the 1960s, and as far back as World War II, passive solar heating systems (which convert solar energy into heat instead of electricity) were used in US homes.

Adopting active solar systems as a consumer product has proven to be a challenge, however. Active solar power uses panels of photovoltaic cells to convert sunlight into electricity, and has traditionally been a prohibitively expensive technology.

The advantages of solar-powered residential buildings are obvious:

• the sun's energy is infinite (at least for the next 5 billion years, give or take),
• provides clean energy,
• no greenhouse gas emissions, and it can save people money on their electric bills.

But there are factors to consider when deciding to go solar - and cost is only one of them.

In this article, we'll look at the six most important questions to consider when you're thinking about investing in solar panel installation. Using photovoltaic energy is a very green solution and a potentially useful step, but it's not quite as easy as getting your energy from the regular electricity grid.

The first factor is one you may not have thought about:

1. Service

Powering your home to use solar energy requires more maintenance than running a regular old power grid. But not by much.

Solar panels have no moving parts. They are part of a complete stationary system. So once they're installed, there's not much that can go wrong. Just about the only thing a homeowner has to do is keep the panels clean. This is an important task because too much snow, dust and bird droppings on the panels can reduce the amount of sunlight. Dust accumulation on the screen can reduce the amount of electricity produced by the system by as much as 7 percent.

This type of maintenance does not need to be done once a week, however. It is enough to water the panels with a hose one to four times a year. You don't need to climb onto the roof to do this. A hose with a ground attachment works great. If there is construction in your area, you will need to clean the panels more often to avoid additional build-up dust buildup.

In addition, check from time to time that all parts are in working order. In addition, the batteries need to be replaced, but this is once a decade.

2. Surroundings

The location of your home has a big impact on your solar energy efficiency. This is an obvious problem: If your electrical power depends on sunlight, things like the shadows of tall trees and tall shadows of buildings will be a problem.

This is an even bigger problem than some people realize. Different types of panels react differently to shadow. While polycrystalline panels can significantly reduce power output, any amount of shading on a monocrystalline panel will stop power production completely.


Thus, to build with solar panels, it is necessary to ensure that there is no shadow on the panel across the roof area during the sunny hours of the day (usually from 10 am to 2 o'clock) and preferably during all sunny hours. The more hours the panels are exposed to full sunlight, the more efficient the electricity production will be.

Achieving the greatest efficiency may mean pruning or completely removing trees on your property. If your home is surrounded by tall buildings that block the sun from the roof, this is a much bigger problem.

3. Insolation

Sunlight obviously plays a key role when it comes to solar energy, and not all regions have a level playing field in this regard. It's important to know how much sunlight reaches the ground in the area where your potential solar home is located.

What we're talking about here is called insolation - a measure of how much solar radiation will fall on the earth in a given area in a given period of time. This is usually measured in kW/m2/days and will tell you how much sunlight will be available for your solar panels to turn into electricity. The higher the insolation value in your area, the more electricity each of your panels will be able to generate. A high insolation value means you can get more energy from smaller panels. A low insolation value means you could end up spending more to achieve the same power output.


So you should build your solar home in the southwest instead of the northwest?
Not at all. It just means you'll probably need more panels to achieve the same power output.

4. Coverage area

Contrary to what most people think, the size of a solar power system has nothing to do with the size of the home.
Instead, there are only two parameters to consider:

• insolation, which we just discussed,
• how much energy do you need.

To get a very rough estimate of how big a system you need, look at your electricity bill and figure out how many kWh you use per day.

The average home uses about 900 kWh per month, or about 30 kWh per day. Multiply this by 0.25. We get 7.5, so we need a 7.5 kW system.

A typical solar panel produces up to 120 watts, or 0.12 kW per day. To supply 7.5 kW, you need about 62 panels. One panel can be approximately 142 by 64 centimeters, so a 62-panel would take up approximately 65 square meters.

You should also consider insolation and how many hours of peak sunlight you get per day, and also make adjustments if you are using batteries with panels. Therefore, it is best to turn to a professional.

5. Expenses

In 1956, solar panels cost about $300 per watt. Only the very rich could afford a 7.5 kW system.

Today prices have dropped significantly. In most areas, solar panels run around $3-5 per watt. You'll pay closer to $3 if you install it yourself, and closer to $5 if you have a professional do it. For 7.5-kW or 7,500-watt panels, you could pay between $22,500 and $37,500.

If you need less electricity, of course the number gets lower. If you only use 600 kWh per month, or 20 kW/day, you could install a system up to 5 kW, which would cost closer to $15,000.

Of course, it is possible to partially provide the house with solar energy. If you want to invest $10,000 in solar panels, you can supplement the electricity from the grid with a 1.5-kW solar system.

However, tens of thousands of dollars for solar panels is still quite an exorbitant expense - especially since it can take decades for that money to be recouped.

Although in the West they already practice renting solar panels. There are no advance payments. Homeowners pay a monthly rent to use the panels, and the rental company owns and maintains them.

6. Disposal

The service life of solar panels is 40-50 years, the controller and inverter are 15-20 years, and the batteries, depending on the type and nature of use, are 4-10 years.
Although the issue of recycling solar panels remains open, only 30% of all manufacturers accept them back for recycling.
But nevertheless, the demand for used solar panels is growing every year. Since the extraction of rare metals is becoming more and more expensive, panels will lead to their reuse.

In addition: there is a secondary market for photo- and wind-electric installations, where already used equipment can find further use.
In countries with economies in transition, previously used solar modules can be used. Thanks to more intense solar radiation, these modules can generate more electricity.
An example of trading is SecondSol, an online platform where used modules are bought and sold.