Non-disclosure of spacecraft solar panels. Ecowatt: Batteries and Solar Panels in Space. Modern projects of NPP Kvant in the field of space photovoltaics

Solar array on the ISS

Solar battery - several combined photoelectric converters (photocells) - semiconductor devices that directly convert solar energy into direct electric current, in contrast to solar collectors that heat the heat-transfer material.

Various devices that allow converting solar radiation into thermal and electrical energy are the object of research in solar energy (from the Greek helios Ήλιος, Helios -). The production of photovoltaic cells and solar collectors is developing in different directions. Solar panels come in a variety of sizes, from those built into calculators to occupying the roofs of cars and buildings.

Story

The first prototypes of solar cells were created by the Italian photochemist of Armenian origin Giacomo Luigi Chamichan.

On April 25, 1954, Bell Laboratories announced the creation of the first silicon-based solar cells to generate electric current. This discovery was made by three company employees - Calvin Souther Fuller, Daryl Chapin and Gerald Pearson. Already 4 years later, on March 17, 1958, the first with solar panels, Vanguard 1, was launched in the USA. Just a couple of months later, on May 15, 1958, Sputnik-3 was launched in the USSR, also using solar panels.

Use in space

Solar panels are one of the main ways to generate electrical energy for: they work for a long time without consuming any materials, and at the same time they are environmentally friendly, unlike nuclear and.

However, when flying at a great distance from the Sun (beyond orbit), their use becomes problematic, since the flow of solar energy is inversely proportional to the square of the distance from the Sun. When flying to and , on the contrary, the power of solar batteries increases significantly (in the region of Venus by 2 times, in the region of Mercury by 6 times).

Efficiency of photocells and modules

The power of the solar radiation flux at the atmospheric entry (AM0) is about 1366 watts per square meter (see also AM1, AM1.5, AM1.5G, AM1.5D). At the same time, the specific power of solar radiation in Europe in very cloudy weather, even during the day, can be less than 100 W/m². With the help of common commercially produced solar panels, it is possible to convert this energy into electricity with an efficiency of 9-24%. In this case, the price of the battery will be about 1-3 US dollars per watt of rated power. With the industrial generation of electricity using photovoltaic cells, the price per kWh will be 0.25 USD. According to the European Photovoltaic Association (EPIA), by 2020 the cost of electricity generated by "solar" systems will decrease to less than 0.10 € per kWh. h for industrial installations and less than 0.15 € per kWh for installations in residential buildings.

In 2009 Spectrolab (a subsidiary of Boeing) demonstrated a solar cell with an efficiency of 41.6%. In January 2011, this company was expected to enter the solar cell market with an efficiency of 39%. In 2011, California-based Solar Junction achieved an efficiency of 43.5% for a 5.5x5.5mm photocell, up 1.2% from the previous record.

In 2012, Morgan Solar created the Sun Simba system from polymethyl methacrylate (Plexiglas), germanium and gallium arsenide, combining a concentrator with a panel on which a photocell is mounted. The efficiency of the system at a fixed position of the panel was 26-30% (depending on the season and the angle at which the Sun is located), twice the practical efficiency of solar cells based on crystalline silicon.

In 2013, Sharp created a three-layer 4x4 mm indium-gallium-arsenide photocell with an efficiency of 44.4%, and a group of specialists from the Fraunhofer Institute for Solar Energy Systems, Soitec, CEA-Leti and the Helmholtz Center Berlin created a photocell, using Fresnel lenses with an efficiency of 44.7%, surpassing his own achievement of 43.6%. In 2014, the Fraunhofer Institute for Solar Energy Systems created solar cells, in which, due to the focusing of light on a very small photocell, the efficiency was 46%.

In 2014, Spanish scientists developed a silicon photovoltaic cell capable of converting infrared radiation from the Sun into electricity.

A promising direction is the creation of photocells based on nanoantennas operating on the direct rectification of currents induced in a small antenna (of the order of 200–300 nm) by light (i.e., electromagnetic radiation with a frequency of about 500 THz). Nanoantennas do not require expensive raw materials for production and have a potential efficiency of up to 85%.

Factors affecting the efficiency of solar cells

Features of the structure of photocells cause a decrease in the performance of the panels with increasing temperature.

From the performance curve of a photovoltaic panel, it can be seen that in order to achieve the greatest efficiency, the correct selection of load resistance is required. To do this, the photovoltaic panels are not connected directly to the load, but use a photovoltaic system management controller that ensures the optimal operation of the panels.

Production

Very often, single photocells do not produce enough power. Therefore, a certain number of photovoltaic cells are combined into so-called photovoltaic solar modules and a reinforcement is mounted between the glass plates. This assembly can be fully automated.

These semiconductor devices convert solar energy into direct electrical current. Simply put, these are the main elements of the device that we call "solar panels". With the help of such batteries, artificial satellites of the Earth operate in space orbits. Such batteries are made here in Krasnodar - at the Saturn plant. Let's go there for a tour.

Photos and text by Rustem Adagamov

The enterprise in Krasnodar is part of the structure of the Federal Space Agency, but Saturn is owned by the Ochakovo company, which literally saved this production in the 90s. The owners of Ochakovo bought out a controlling stake, which almost went to the Americans.

A lot of money was invested here and modern equipment was purchased, and now Saturn is one of the two leaders in the Russian market for the production of solar and storage batteries for the needs of the space industry - civil and military. All the profit that Saturn receives remains here in Krasnodar and goes to the development of the production base.

So, it all starts here - on the site of the so-called. gas phase epitaxy. There is a gas reactor in this room, in which a crystalline layer is grown on a germanium substrate for 3 hours, which will serve as the basis for a future photocell. The cost of such an installation is about 3 million euros:

After that, the substrate still has a long way to go: electrical contacts will be applied to both sides of the photocell (moreover, on the working side, the contact will have a “comb pattern”, the dimensions of which are carefully calculated to ensure the maximum passage of sunlight), an anti-reflective coating will appear on the substrate and etc. - in total more than two dozen technological operations at various installations before the photocell becomes the basis of a solar battery.

For example, photolithography installation. Here, on the photocells, “patterns” of electrical contacts are formed. The machine performs all operations automatically, according to a given program. Here, the light is appropriate, which does not harm the light-sensitive layer of the photocell - as before, in the era of analog photography, we used "red" lamps ^

In the vacuum of the sputtering installation, electrical contacts and dielectrics are deposited using an electron beam, as well as antireflection coatings are applied (they increase the current generated by the photocell by 30%):

Well, the photocell is ready and you can start assembling the solar battery. Tires are soldered to the surface of the photocell in order to then connect them to each other, and a protective glass is glued on them, without which in space, under radiation conditions, the photocell may not withstand loads. And, although the thickness of the glass is only 0.12 mm, a battery with such photocells will work for a long time in orbit (more than 15 years in high orbits).

The electrical connection of the photocells to each other is carried out by silver contacts (they are called shank) with a thickness of only 0.02 mm.

To obtain the desired voltage in the network, produced by the solar battery, the photocells are connected in series. This is what a section of series-connected photocells looks like (photovoltaic converters - that's right):

Finally, the solar panel is assembled. Only part of the battery is shown here - the panel in layout format. There can be up to eight such panels on the satellite, depending on how much power is needed. On modern communication satellites, it reaches 10 kW. The panels will be mounted on a satellite, they will open in space like wings and with their help we will watch satellite TV, use satellite Internet, navigation systems (GLONASS satellites use Krasnodar solar panels):

When the spacecraft is illuminated by the Sun, the electricity generated by the solar battery feeds the systems of the apparatus, and the excess energy is stored in the battery. When the spacecraft is in the shadow of the Earth, the spacecraft uses the electricity stored in the battery. Nickel hydrogen battery, having a high energy intensity (60 Wh/kg) and an almost inexhaustible resource, is widely used on spacecraft. The production of such batteries is another part of the work of the Saturn plant.

In this picture, the assembly of a nickel-hydrogen battery is being carried out by Anatoly Dmitrievich Panin, holder of the medal of the Order of Merit for the Fatherland, II degree:

Assembly site for nickel-hydrogen batteries. The filling of the battery is being prepared for placement in the case. The filling is positive and negative electrodes separated by separator paper - in them the transformation and accumulation of energy takes place:

Installation for electron beam welding in a vacuum with which the battery case is made of thin metal:

A section of the workshop where cases and parts of accumulators are tested for the effect of increased pressure. Due to the fact that the accumulation of energy in the battery is accompanied by the formation of hydrogen, and the pressure inside the battery rises, leak tests are an integral part of the battery manufacturing process:

The body of a nickel-hydrogen battery is a very important part of the entire device operating in space. The case is designed for a pressure of 60 kg s / cm 2, during tests the rupture occurred at a pressure of 148 kg s / cm 2:

Batteries tested for strength are filled with electrolyte and hydrogen, after which they are ready for use:

The body of a nickel-hydrogen battery is made of a special alloy of metals and must be mechanically strong, light and have high thermal conductivity. Batteries are installed in cells and do not touch each other:

Accumulators and the batteries assembled from them are subjected to electrical tests at our own production facilities. In space, it will be impossible to fix or replace anything, so every product is carefully tested here.

All space technology is subjected to mechanical impact tests using vibration stands that simulate the loads during the launch of a spacecraft into orbit.

In general, the Saturn plant made the most favorable impression. The production is well organized, the workshops are clean and bright, the people are qualified, it is a pleasure and very interesting to communicate with such specialists for a person who is at least to some extent interested in our space. I left the Saturn in a great mood - it's always nice to see a place where they don't engage in empty chatter and don't shift papers, but do real, serious business, successfully compete with the same manufacturers in other countries. There would be more of this in Russia.

In contact with

These are photovoltaic converters - semiconductor devices that convert solar energy into direct electric current. Simply put, these are the main elements of the device that we call "solar panels". With the help of such batteries, artificial satellites of the Earth operate in space orbits. Such batteries are made here in Krasnodar - at the Saturn plant. The plant management invited the author of this blog to look at the production process and write about it in his diary.

1. The enterprise in Krasnodar is part of the structure of the Federal Space Agency, but Saturn is owned by the Ochakovo company, which literally saved this production in the 90s. The owners of Ochakovo bought out a controlling stake, which almost went to the Americans. Ochakovo has invested heavily here, purchased modern equipment, managed to retain specialists, and now Saturn is one of the two leaders in the Russian market for the production of solar and storage batteries for the needs of the space industry - civil and military. All the profit that Saturn receives remains here in Krasnodar and goes to the development of the production base.

2. So, it all starts here - on the site of the so-called. gas phase epitaxy. There is a gas reactor in this room, in which a crystalline layer is grown on a germanium substrate for three hours, which will serve as the basis for a future photocell. The cost of such an installation is about three million euros.

3. After that, the substrate still has a long way to go: electrical contacts will be applied to both sides of the photocell (moreover, on the working side, the contact will have a “comb pattern”, the dimensions of which are carefully calculated to ensure maximum passage of sunlight), an anti-reflective coating will appear on the substrate coating, etc. - in total more than two dozen technological operations at various installations before the photocell becomes the basis of a solar battery.

4. Here, for example, is the installation of photolithography. Here, on the photocells, “patterns” of electrical contacts are formed. The machine performs all operations automatically, according to a given program. Here, the light is appropriate, which does not harm the photosensitive layer of the photocell - as before, in the era of analog photography, we used "red" lamps.

5. In the vacuum of the sputtering installation, electrical contacts and dielectrics are applied using an electron beam, as well as antireflection coatings are applied (they increase the current generated by the photocell by 30%).

6. Well, the photocell is ready and you can start assembling the solar battery. Tires are soldered to the surface of the photocell in order to then connect them to each other, and a protective glass is glued on them, without which in space, under radiation conditions, the photocell may not withstand loads. And, although the thickness of the glass is only 0.12 mm, a battery with such photocells will work for a long time in orbit (more than fifteen years in high orbits).

6a

6b

7. The electrical connection of the photocells with each other is carried out by silver contacts (they are called shank) with a thickness of only 0.02 mm.

8. To obtain the desired voltage in the network, produced by the solar battery, the photocells are connected in series. This is how a section of series-connected photocells looks like (photoelectric converters - that's right).

9. Finally, the solar panel is assembled. Only part of the battery is shown here - the panel in layout format. There can be up to eight such panels on the satellite, depending on how much power is needed. On modern communication satellites, it reaches 10 kW. Such panels will be mounted on a satellite, in space they will open up like wings and with their help we will watch satellite TV, use satellite Internet, navigation systems (Glonass satellites use Krasnodar solar panels).

9a

10. When the spacecraft is illuminated by the Sun, the electricity generated by the solar battery feeds the systems of the apparatus, and the excess energy is stored in the battery. When the spacecraft is in the shadow of the Earth, the spacecraft uses the electricity stored in the battery. The nickel-hydrogen battery, having a high energy capacity (60 Wh/kg) and an almost inexhaustible resource, is widely used in spacecraft. The production of such batteries is another part of the work of the Saturn plant.

In this picture, Anatoly Dmitrievich Panin, holder of the medal of the Order of Merit for the Fatherland, II degree, is assembling a nickel-hydrogen battery.

10a

11. Assembly site for nickel-hydrogen batteries. The filling of the battery is being prepared for placement in the case. The filling is positive and negative electrodes separated by separator paper - in them the transformation and accumulation of energy takes place.

12. Installation for electron-beam welding in vacuum, with which the battery case is made of thin metal.

13. A section of the workshop where the cases and parts of the batteries are tested for the effects of high pressure.
Due to the fact that the accumulation of energy in the battery is accompanied by the formation of hydrogen, and the pressure inside the battery rises, leak testing is an integral part of the battery manufacturing process.

14. The case of a nickel-hydrogen battery is a very important part of the entire device operating in space. The body is designed for a pressure of 60 kg·s/cm 2 , during testing the rupture occurred at a pressure of 148 kg·s/cm 2 .

15. Batteries tested for strength are filled with electrolyte and hydrogen, after which they are ready for use.

16. The body of the nickel-hydrogen battery is made of a special alloy of metals and must be mechanically strong, light and have high thermal conductivity. Batteries are installed in cells and do not touch each other.

17. Accumulators and batteries assembled from them are subjected to electrical tests at our own production facilities. In space, it will be impossible to fix or replace anything, so every product is carefully tested here.

17a

17b

18. All space technology is subjected to tests for mechanical effects using vibration stands that simulate the load during the launch of the spacecraft into orbit.

18a

19. In general, the Saturn plant made the most favorable impression. The production is well organized, the workshops are clean and bright, the people are qualified, it is a pleasure and very interesting to communicate with such specialists for a person who is at least to some extent interested in our space. I left the Saturn in a great mood - it's always nice to see a place where they don't engage in empty chatter and don't shift papers, but do real, serious business, successfully compete with the same manufacturers in other countries. There would be more of this in Russia.

Photos: © drugoi

P.S. Blog of the Vice President for Marketing of the Ochakovo company

Batteries and solar panels, solar panels, alternative energy, solar energy

On the first satellites of the Earth, the equipment consumed relatively small current powers and its operation time was very short. Therefore, as the first space energy sources, ordinary accumulators.

As you know, on an airplane or car, the battery is an auxiliary current source and works in conjunction with an electric machine generator, from which it is periodically recharged.

The main advantages of batteries are their high reliability and excellent performance. A significant disadvantage of rechargeable batteries is their high weight with low energy consumption. For example, a silver-zinc battery with a capacity of 300 Ah weighs about 100 kg. This means that with a current power of 260 watts (normal consumption on a manned satellite "Mercury"), such a battery will work for less than two days. The specific weight of the battery, which characterizes the weight perfection of the current source, will be about 450 kg / kW.

Therefore, the battery as an autonomous current source has been used in space until now only at low power consumption (up to 100 W) with a service life of several tens of hours.

Large automatic satellites of the Earth, saturated with a variety of equipment, required more powerful and lighter current sources with a very long duration - up to several weeks and even months.

Such current sources were purely space generators - semiconductor photovoltaic cells operating on the principle of converting the light energy of solar radiation directly into electricity. These generators are called solar panels .

We have already talked about the power of the thermal radiation of the Sun. Recall that outside the earth's atmosphere, the intensity of solar radiation is quite significant: the flux of energy incident on the surface perpendicular to the sun's rays is 1340 watts per 1 mg. This energy, or rather, the ability of solar radiation to create photoelectric effects, is used in solar batteries. The principle of operation of a silicon solar battery is shown in fig. thirty.

The thin wafer consists of two layers of silicon with different physical properties. The inner layer is pure monocrystalline silicon. Outside, it is covered with a very thin layer of "contaminated" silicon, for example, with an admixture of phosphorus. After irradiating such a “wafer” with sunlight, an electron flow occurs between the layers and a potential difference is formed, and an electric current appears in the external circuit connecting the layers.

The thickness of the silicon layer is required to be negligible, but due to the imperfection of the technology, it usually ranges from 0.5 to 1 mm, although only about 2% of the thickness of this layer takes part in the creation of the current. For technological reasons, the surface of one solar battery element turns out to be very small, which requires a large number of elements to be connected in series in a circuit.

A silicon solar battery gives current only when the sun's rays fall on its surface, and the maximum current removal will be when the battery plane is perpendicular to the sun's rays. This means that during the movement of a spacecraft or a spacecraft in orbit, a constant orientation of the batteries to the Sun is necessary. Batteries will not provide current in the shade, so they must be used in conjunction with another source of current, such as a battery. The latter will serve not only as a storage device, but also as a damper for possible fluctuations in the amount of energy required.

efficiency solar panels is small, it does not exceed 11-13% so far. This means that from 1 m 2 of modern solar batteries, the power is about 100-130 watts. True, there are opportunities to increase efficiency. solar batteries (theoretically up to 25%) by improving their design and improving the quality of the semiconductor layer. It is proposed, for example, to superimpose two or more batteries one on top of the other so that the lower surface uses that part of the solar energy spectrum that the upper layer passes without absorbing.

efficiency battery depends on the surface temperature of the semiconductor layer. The maximum efficiency is achieved at 25°C, and with an increase in temperature to 300C, the efficiency increases. is almost halved. Solar panels are advantageous to use, as well as batteries, for small current consumption due to their large surface area and high specific gravity. To obtain, for example, a power of 3 kW, a battery is required, consisting of 100,000 cells with a total weight of about 300 kg, i.e. with a specific weight of 100 kg/kW. Such batteries will occupy an area of ​​​​more than 30 m 2.

Nevertheless, solar batteries have proven themselves in space as a fairly reliable and stable source of energy that can work for a very long time.

The main danger to solar cells in space is cosmic radiation and meteor dust, which cause surface erosion of silicon cells and limit battery life.

For small inhabited stations, this current source will apparently remain the only acceptable and sufficiently efficient one, but large OCS will require other energy sources, more powerful and with a lower specific gravity. At the same time, it is necessary to take into account the difficulties of obtaining alternating current with the help of solar batteries, which will be required for large scientific space laboratories.

In 2016 (a key division of IPPT - ) designed an ultra-lightweight composite mesh solar panel for spacecraft. The lightweight support structure, developed within the concept of IPPT SPbPU, is designed to replace three-layer panels with honeycomb core. The product is manufactured at the enterprise of IPPT's partner - Baltico (Germany).

The development was repeatedly demonstrated at industrial exhibitions, including at the forum, where, in particular, it attracted the attention of the First Deputy Minister of Industry and Trade of Russia G.S. Nikitin and other government officials, as well as the heads of a number of leading industrial enterprises.

Innoprom-2016. Scientific adviser of IPPT SPbPU, head of the Engineering Center of SPbPU A.I. Borovkov (right) demonstrates a composite panel for space solar arrays, developed by IPPT SPbPU and Baltico GmbH, to First Deputy Minister of Industry and Trade of Russia G.S. Nikitin (in the center) and Director of the Department of Machine Tool Building and Investment Machine Building of the Ministry of Industry and Trade of Russia M.I. Ivanov

The composite panel was also demonstrated to the Minister of Industry and Trade D.V. Manturov, who visited Peter the Great St. Petersburg Polytechnic University on November 7, 2016.

A.I. Borovkov tells the head of the Ministry of Industry and Trade D.V. Manturov about the
Ultralight Composite Solar Panel

Material: composite - carbon fiber / epoxy matrix

Technology: Digital additive manufacturing. Robotic placement of continuous fibers on the frame.

Production cycle: 15 minutes

Serial production cost: from 6000 rubles / sq. m.

Technology advantages:

• maximum use of the characteristics of a unidirectional composite material along the reinforcing fibers;
• direct process, use of primary materials (roving and binder);
• compatibility with metal structures;
• low material consumption and cost of structures;
• non-waste production;
• the possibility of manufacturing complex geometric shapes, modularity;
• reducing the weight of load-bearing structures by 20-30 times;
• fully automated technology;
• manufacturing accuracy 0.1-1.0 mm;
• use of domestic materials.