Misplaced Pages

#50949

120-746: The name Queqiao ( ch'wuh-ch'yow , "Magpie Bridge") was inspired by and came from the Chinese tale The Cowherd and the Weaver Girl . The initial phase of the International Lunar Research Station (ILRS), consisting of the Chang'e 7 and Chang'e 8 probes, was scheduled to be built in 2026 and 2028 on the southern edge of the South Pole–Aitken basin located on the far side of the Moon . While

240-422: A PV system or solar power system , is an electric power system designed to supply usable solar power by means of photovoltaics . It consists of an arrangement of several components, including solar panels to absorb and convert sunlight into electricity, a solar inverter to convert the output from direct to alternating current , as well as mounting , cabling , and other electrical accessories to set up

360-456: A band is used to transmit payload data to the ground stations of the Chinese Academy of Sciences , both from the surface probes on the Moon and from the satellite itself. With quadrature phase shift keying, encryption with low-density parity check code and a traveling wave tube amplifier with 55 W output power, the data transfer rate is on average 100 Mbit/s. The antenna used

480-521: A band signals are subject to strong attenuation by the water droplets in the Earth's atmosphere during the hot and wet season , the payload data can also be transmitted via the S-band, but only with a data transfer rate of a maximum of 6 Mbit/s. Similar to a satellite navigation system, the time of arrival , i.e., a transit time measurement of the signals between the partners involved in communication,

600-444: A parabolic antenna with a diameter of 4.2 m and an antenna gain of 44 dBi is permanently mounted on the top of the bus- the alignment is carried out via the satellite's attitude control - and is used for radio communication with the lunar surface. In order to be able to accommodate the satellite in the payload fairing of the launch vehicle , the segments of the reflector are folded together during launch. After separating from

720-404: A small orbit correction maneuver approximately every 9 days. Therefore, a frozen elliptic orbit around the Moon itself was chosen for Queqiao 2 due to its more stable nature. The frozen elliptic orbit can provide visual contact with the Moon for eight hours, i.e., two-thirds of its 12-hour orbit, since the point of its periselene lies above the side of the southern polar region facing away from

840-414: A "sea" of unpowered lines, as the solar array continues to deliver DC power during the power outage. Islanding is a hazard to utility workers, who may not realize that an AC circuit is still powered, and it may prevent automatic re-connection of devices. Anti-Islanding feature is not required for complete Off-Grid Systems. Although still expensive, PV systems increasingly use rechargeable batteries to store

960-425: A PV cell is defined as the fraction of incident solar irradiance that is absorbed by the cell. When the sun is at the zenith on a cloudless day, the power of the sun is about 1 kW /m , on the Earth's surface, to a plane that is perpendicular to the sun's rays. As such, PV arrays can track the sun through each day to greatly enhance energy collection. However, tracking devices add cost, and require maintenance, so it

1080-403: A PV solar installation varies greatly and is typically less useful than a calculation of return on investment . While it is typically calculated to be between 10 and 20 years, the financial payback period can be far shorter with incentives . The temperature effect on photovoltaic modules is usually quantified by means of some coefficients relating the variations of the open‐circuit voltage, of

1200-443: A balance of system may include any or all of the following: renewable energy credit revenue-grade meter, maximum power point tracker (MPPT), battery system and charger , GNSS solar tracker , energy management software , solar irradiance sensors, anemometer , or task-specific accessories designed to meet specialized requirements for a system owner. In addition, a CPV system requires optical lenses or mirrors and sometimes

1320-427: A cell that can reach 44.7% efficiency using the equivalent of "297 suns". Photovoltaic cell electrical output is extremely sensitive to shading (the so-called "Christmas light effect"). When even a small portion of a cell or of a module or array of cells in parallel is shaded, with the remainder in sunlight, the output falls dramatically due to internal 'short-circuiting' (the electrons reversing course through

SECTION 10

#1732855950051

1440-407: A cooling system. The terms "solar array" and "PV system" are often incorrectly used interchangeably, despite the fact that the solar array does not encompass the entire system. Moreover, "solar panel" is often used as a synonym for "solar module", although a panel consists of a string of several modules. The term "solar system" is also an often used misnomer for a PV system. The building blocks of

1560-631: A large elliptical orbit around the Moon (Both were attached to each other and separated in lunar orbit on 3 April 2024). Both are equipped with a communications payload and first one has a laser passive retroreflector and an in-space router, with another has navigational devices. In a large elliptical orbit around the moon, satellite-to-ground laser ranging are inter-satellite microwave ranging are to be carried out by these satellites via high-precision lunar orbit determination technology. On 12 April 2024, CNSA announced that Queqiao-2 had successfully completed in-orbit communication tests with Chang'e 4 on

1680-405: A large portion of sunlight directly. In diffuse light (i.e. under cloud or fog), tracking has little or no value. Because most concentrated photovoltaics systems are very sensitive to the sunlight's angle, tracking systems allow them to produce useful power for more than a brief period each day. Tracking systems improve performance for two main reasons. First, when a solar panel is perpendicular to

1800-420: A large rack is mounted on the ground, and the modules mounted on the rack. For buildings, many different racks have been devised for pitched roofs. For flat roofs, racks, bins and building integrated solutions are used. Solar panel racks mounted on top of poles can be stationary or moving, see Trackers below. Side-of-pole mounts are suitable for situations where a pole has something else mounted at its top, such as

1920-607: A large temperature range. Specific performance requirements for material used for wiring a solar panel installation are given in national and local electrical codes which regulate electrical installations in an area. General features required for solar cables are resistance to ultraviolet light, weather, temperature extremes of the area and insulation suitable for the voltage class of the equipment. Different jurisdictions will have specific rules regarding grounding (earthing) of solar power installations for electric shock protection and lightning protection. A solar tracking system tilts

2040-445: A light fixture or an antenna. Pole mounting raises what would otherwise be a ground mounted array above weed shadows and livestock, and may satisfy electrical code requirements regarding inaccessibility of exposed wiring. Pole mounted panels are open to more cooling air on their underside, which increases performance. A multiplicity of pole top racks can be formed into a parking carport or other shade structure. A rack which does not follow

2160-565: A local scale - such as those from snow or the effects of surface coatings (e.g. hydrophobic or hydrophilic ) on soiling or snow losses. (Although in heavy snow environments with severe ground interference can result in annual losses from snow of 30%. ) Access to the Internet has allowed a further improvement in energy monitoring and communication. Dedicated systems are available from a number of vendors. For solar PV systems that use microinverters (panel-level DC to AC conversion), module power data

2280-593: A modified version of the conventional lead–acid battery  – nickel–cadmium and lithium-ion batteries. Compared to the other types, lead-acid batteries have a shorter lifetime and lower energy density. However, due to their high reliability, low self discharge as well as low investment and maintenance costs, they are currently (as of 2014) the predominant technology used in small-scale, residential PV systems, as lithium-ion batteries are still being developed and about 3.5 times as expensive as lead-acid batteries. Furthermore, as storage devices for PV systems are stationary,

2400-464: A period of 10 years, the assumed lifespan of the satellite. However, it did not enter that orbit and instead entered a 119.25° 1992 × 18679 km retrograde orbit. Queqiao 2 relay satellite and radio observatory is based on the CAST 2000 bus from DFH Satellite , a subsidiary of the Chinese Academy of Space Technology . It carries a total of 488 kg (1,076 lb) of hydrazine and oxidizer in tanks with

2520-552: A photovoltaic system are solar cells. A solar cell is the electrical device that can directly convert photons energy into electricity. There are three technological generations of solar cells: the first generation (1G) of crystalline silicon cells (c-Si), the second generation (2G) of thin-film cells (such as CdTe , CIGS , Amorphous Silicon , and GaAs ), and the third generation (3G) of organic , dye-sensitized , Perovskite and multijunction cells . Conventional c-Si solar cells , normally wired in series, are encapsulated in

SECTION 20

#1732855950051

2640-447: A rechargeable lithium-ion battery with the aim to revolutionize energy consumption. PV systems with an integrated battery solution also need a charge controller , as the varying voltage and current from the solar array requires constant adjustment to prevent damage from overcharging. Basic charge controllers may simply turn the PV panels on and off, or may meter out pulses of energy as needed,

2760-477: A result of grid constraints preventing feedback of unused electricity into the grid as well as increased electricity costs resulting in improved economics. A typical residential solar array is rack-mounted on the roof, rather than integrated into the roof or facade of the building, which is significantly more expensive. Utility-scale solar power stations are ground-mounted, with fixed tilted solar panels rather than using expensive tracking devices. Crystalline silicon

2880-616: A shaded cell may drop 8 volts, instead of adding 0.5 volts, at a high current level, thereby absorbing the power produced by 16 other cells. It is thus important that a PV installation not be shaded by trees or other obstructions. There are techniques to mitigate the losses with diodes, but these techniques also entail losses. Several methods have been developed to determine shading losses from trees to PV systems over both large regions using LiDAR , but also at an individual system level using 3D modeling software . Most modules have bypass diodes between each cell or string of cells that minimize

3000-578: A significant role in output depending on the surface around the photovoltaic system and the type of solar cell material. A photovoltaic installation in the northern latitudes of Europe or the United States may expect to produce 1 kWh/m /day. A typical 1 kW photovoltaic installation in Australia or the southern latitudes of Europe or United States, may produce 3.5–5 kWh per day, dependent on location, orientation, tilt, insolation and other factors. In

3120-496: A single home, or an isolated device in the form of AC or DC electric. Military and civilian Earth observation satellites , street lights , construction and traffic signs, electric cars , solar-powered tents, and electric aircraft may contain integrated photovoltaic systems to provide a primary or auxiliary power source in the form of AC or DC power, depending on the design and power demands. In 2013, rooftop systems accounted for 60 percent of worldwide installations. However, there

3240-447: A small portion of the market. Operating silently and without any moving parts or air pollution , PV systems have evolved from niche market applications into a mature technology used for mainstream electricity generation. Due to the growth of photovoltaics , prices for PV systems have rapidly declined since their introduction; however, they vary by market and the size of the system. Nowadays, solar PV modules account for less than half of

3360-468: A solar module to protect them from the weather. The module consists of a tempered glass as cover, a soft and flexible encapsulant , a rear backsheet made of a weathering and fire-resistant material and an aluminium frame around the outer edge. Electrically connected and mounted on a supporting structure, solar modules build a string of modules, often called solar panel. A solar array consists of one or many such panels. A photovoltaic array, or solar array,

3480-504: A solar panel throughout the day. Depending on the type of tracking system, the panel is either aimed directly at the Sun or the brightest area of a partly clouded sky. Trackers greatly enhance early morning and late afternoon performance, increasing the total amount of power produced by a system by about 20–25% for a single axis tracker and about 30% or more for a dual axis tracker, depending on latitude. Trackers are effective in regions that receive

3600-546: A strategy called PWM or pulse-width modulation . More advanced charge controllers will incorporate MPPT logic into their battery charging algorithms. Charge controllers may also divert energy to some purpose other than battery charging. Rather than simply shut off the free PV energy when not needed, a user may choose to heat air or water once the battery is full. The metering must be able to accumulate energy units in both directions, or two meters must be used. Many meters accumulate bidirectionally, some systems use two meters, but

3720-407: A surplus to be later used at night. Batteries used for grid-storage also stabilize the electrical grid by leveling out peak loads , and play an important role in a smart grid , as they can charge during periods of low demand and feed their stored energy into the grid when demand is high. Common battery technologies used in today's PV systems include the valve regulated lead-acid battery  –

Queqiao-2 - Misplaced Pages Continue

3840-448: A total capacity of 606 L (133 imp gal; 160 US gal), giving it a take-off weight of around 1,200 kg (2,600 lb). The three-axis stabilized satellite has eight engines with a thrust of 20 N each for orbit correction maneuvers as well as eight engines with a thrust of 5 N each and four engines with a thrust of 1 N each for attitude control; it can be aligned with an accuracy of 0.03° (three times as good as

3960-533: A unidirectional meter (with detent) will not accumulate energy from any resultant feed into the grid. In some countries, for installations over 30  kW p a frequency and a voltage monitor with disconnection of all phases is required. This is done where more solar power is being generated than can be accommodated by the utility, and the excess can not either be exported or stored . Grid operators historically have needed to provide transmission lines and generation capacity. Now they need to also provide storage. This

4080-452: A voltage range that can charge 12-volt batteries directly, so addition of a PV system requires only panels, a charge controller, and wiring. Solar systems on recreation vehicles are usually constrained in wattage by the physical size of the RV's roof space. In urban and suburban areas, photovoltaic arrays are often used on rooftops to supplement power use; often the building will have a connection to

4200-405: A working system. Many utility-scale PV systems use tracking systems that follow the sun's daily path across the sky to generate more electricity than fixed-mounted systems. PV systems convert light directly into electricity and are not to be confused with other solar technologies, such as concentrated solar power or solar thermal , used for heating and cooling. A solar array only encompasses

4320-481: Is cost-effective . In 2018, the estimated soiling-induced revenue loss was estimated to between 5 and 7 billion euros. The long‐term reliability of photovoltaic modules is crucial to ensure the technical and economic viability of PV as a successful energy source. The analysis of degradation mechanisms of PV modules is key to ensure current lifetimes exceeding 25 years. Solar insolation is made up of direct, diffuse, and reflected radiation . The absorption factor of

4440-473: Is a linked collection of solar modules. The power that one module can produce is seldom enough to meet requirements of a home or a business, so the modules are linked together to form an array. Most PV arrays use an inverter to convert the DC power produced by the modules into alternating current that can power lights , motors, and other loads. The modules in a PV array are usually first connected in series to obtain

4560-531: Is a notable trend towards utility-scale systems, as the focus on new installations is shifting away from Europe to sunnier regions, such as the Sunbelt in the U.S., which are less opposed to ground-mounted solar farms and cost-effectiveness is more emphasized by investors. Driven by advances in technology and increases in manufacturing scale and sophistication, the cost of photovoltaics is declining continuously. There are several million PV systems distributed all over

4680-468: Is a small parabolic antenna with a diameter of 0.6 m in a gimbal suspension, which is mounted on the nadir side of the satellite bus on a fold-out arm that allows it to protrude above the large parabolic antenna. Telemetry and control of the satellite is usually carried out on the S-band , for which there is an S-band omnidirectional antenna at the focal point of the small parabolic antenna in addition to

4800-707: Is a trend away from rooftop and towards utility-scale PV systems, as the focus of new PV installations is also shifting from Europe to countries in the sunbelt region of the planet where opposition to ground-mounted solar farms is less accentuated. Portable and mobile PV systems provide electrical power independent of utility connections, for "off the grid" operation. Such systems are so commonly used on recreational vehicles and boats that there are retailers specializing in these applications and products specifically targeted to them. Since recreational vehicles (RV) normally carry batteries and operate lighting and other systems on nominally 12-volt DC power, RV systems normally operate in

4920-451: Is about a square meter in size. Such a module may be expected to produce 0.75 kilowatt-hour (kWh) every day, on average, after taking into account the weather and the latitude, for an insolation of 5 sun hours/day. Module output degrades faster at increased temperature. Allowing ambient air to flow over, and if possible behind, PV modules reduces this problem, as the airflow tend to reduce the operating temperature and, as consequence, increase

Queqiao-2 - Misplaced Pages Continue

5040-424: Is around 10 kilowatts and mounted on a sloped roof, while commercial systems may reach a megawatt-scale and are generally installed on low-slope or even flat roofs. Although rooftop mounted systems are small and have a higher cost per watt than large utility-scale installations, they account for the largest share in the market. There is, however, a growing trend towards bigger utility-scale power plants, especially in

5160-466: Is assembled into a protective weatherproof enclosure, thus making a photovoltaic module or solar panel . Modules may then be strung together into a photovoltaic array. In 2012, solar panels available for consumers had an efficiency of up to about 17%, while commercially available panels can go as far as 27%. By concentrating the sunlight it is possible to achieve higher efficiencies. A group from The Fraunhofer Institute for Solar Energy Systems has created

5280-426: Is automatically provided. Some systems allow setting performance alerts that trigger phone/email/text warnings when limits are reached. These solutions provide data for the system owner and the installer. Installers are able to remotely monitor multiple installations, and see at-a-glance the status of their entire installed base. A photovoltaic system for residential, commercial, or industrial energy supply consists of

5400-573: Is bright; slanting is the Weaving Lady, during one day she is seven times removed. Although she is seven times removed, she does not achieve any interwoven pattern; brilliant is the Draught Ox, But one does not yoke into any carriage. … The Cowherd and the Weaver Girl originated from people’s worship of natural celestial phenomena, and later developed into the Qiqiao or Qixi Festival since

5520-564: Is critical for revenue and O&M efficiency. Monitoring of array performance may be part of contractual agreements between the array owner, the builder, and the utility purchasing the energy produced. A method to create "synthetic days" using readily available weather data and verification using the Open Solar Outdoors Test Field make it possible to predict photovoltaic systems performance with high degrees of accuracy. This method can be used to then determine loss mechanisms on

5640-501: Is directed to the place where supernatural women bathe by a cow or a deer; the women may be Swan Maidens, a celestial weaver, one of the Pleiades , one of the "9 Celestial Maidens", or a fairy; he steals the garments of one of them and makes her his wife; she finds the garments and flies back to Heaven; the youth goes after her, and meets her in the Heavenly realm; the Heavenly king decrees that

5760-425: Is expected to operate for 8–10 years and by using a elliptical frozen orbit of 200 km × 16,000 km with an inclination of 62.4°, instead of the L 2 halo orbit . The initial mission of Queqiao-2 is to provide relay communication support for Chang'e 6. After Chang'e 6 completed its mission, it adjusted its orbit to provide services for Chang'e-7, Chang'e-8 and subsequent lunar exploration missions. In

5880-420: Is more common for PV arrays to have fixed mounts that tilt the array and face due south in the northern hemisphere or due north in the southern hemisphere. The tilt angle from horizontal can be varied for season, but if fixed, should be set to give optimal array output during the peak electrical demand portion of a typical year for a stand-alone system. This optimal module tilt angle is not necessarily identical to

6000-429: Is needed. If both of those fail, installations over 30kWp can automatically shut down, although in practice all inverters maintain voltage regulation and stop supplying power if the load is inadequate. Grid operators have the option of curtailing excess generation from large systems, although this is more commonly done with wind power than solar power, and results in a substantial loss of revenue. Three-phase inverters have

6120-407: Is normally hydro-storage, but other means of storage are used. Initially storage was used so that baseload generators could operate at full output. With variable renewable energy , storage is needed to allow power generation whenever it is available, and consumption whenever needed. The two variables a grid operator has are storing electricity for when it is needed, or transmitting it to where it

SECTION 50

#1732855950051

6240-547: Is referenced in various literary and popular cultural sources. The tale has been alluded to in many literary works. One of the most famous was the poem by Qin Guan (秦观; 1049–1100) during the Song dynasty : 鵲橋仙 纖雲弄巧， 飛星傳恨， 銀漢迢迢暗渡。 金風玉露一相逢， 便勝卻人間無數。 柔情似水， 佳期如夢， 忍顧鵲橋歸路。 兩情若是久長時， 又豈在朝朝暮暮。 Meeting across the Milky way Through the varying shapes of the delicate clouds,

6360-479: Is required. A solar inverter may connect to a string of solar panels. In some installations a solar micro-inverter is connected at each solar panel. For safety reasons a circuit breaker is provided both on the AC and DC side to enable maintenance. AC output may be connected through an electricity meter into the public grid. The number of modules in the system determines the total DC watts capable of being generated by

6480-430: Is stored or used directly by island/standalone plant. PV systems are generally designed in order to ensure the highest energy yield for a given investment. Some large photovoltaic power stations such as Solar Star , Waldpolenz Solar Park and Topaz Solar Farm cover tens or hundreds of hectares and have power outputs up to hundreds of megawatts . A small PV system is capable of providing enough AC electricity to power

6600-456: Is the predominant material used in 90 percent of worldwide produced solar modules, while its rival thin-film has lost market-share. About 70 percent of all solar cells and modules are produced in China and Taiwan, only 5 percent by European and US- manufacturers . The installed capacity for both small rooftop systems and large solar power stations is growing rapidly and in equal parts, although there

6720-548: Is used to determine their position in orbit or on the surface of the Moon with high accuracy. There are three scientific payloads on the spacecraft: Queqiao-2 was launched on 20 March 2024 at 00:31 UTC by a Long March 8 rocket from the Wenchang Space Launch Site , supporting China's Chang'e 6 in 2024 and future 7 and 8 lunar missions scheduled for 2026 and 2028 respectively. The upgraded Queqiao-2 entered lunar orbit on 24 March 2024 at 16:46 UTC , where it

6840-512: Is used, the so-called energy payback time decreases to one year or less. Net metering and financial incentives, such as preferential feed-in tariffs for solar-generated electricity, have also greatly supported installations of PV systems in many countries. The levelised cost of electricity from large-scale PV systems has become competitive with conventional electricity sources in an expanding list of geographic regions, and grid parity has been achieved in about 30 countries. As of 2015,

6960-502: The Doppler shift of the carrier wave for the telemetry signals , and long-base interferometry , where connected radio telescopes are using the Chinese VLBI network to determine the exact angular position . The systems are alternately redundant. In the event of a failure of the S-band system, the telemetry and control signals can also be transmitted via the K a band, and if the K

7080-655: The Han Dynasty . It has also been celebrated as the Tanabata festival in Japan and the Chilseok festival in Korea. In ancient times, women would make wishes to the stars of Vega and Altair in the sky during the festival, hoping to have a wise mind, a dexterous hand (in embroidery and other household tasks), and a good marriage. The story was selected as one of China's Four Great Folktales by

7200-669: The Queqiao so far only had to connect with two probes on the far side of the Moon ( Chang'e 4 lander and Yutu-2 rover), future mission would include more workload, with up to ten robots being active on the moon for the ILRS project, which requires a complex and sophisticated communication network. The Queqiao relay satellite was inserted in a halo orbit around the Earth-Moon L 2 since 2018. China planned another relay satellite, called Queqiao 2 , to support and supplement Queqiao-1. Originally,

7320-606: The Sahara desert, with less cloud cover and a better solar angle, one could ideally obtain closer to 8.3 kWh/m /day provided the nearly ever present wind would not blow sand onto the units. The area of the Sahara desert is over 9 million km . 90,600 km , or about 1%, could generate as much electricity as all of the world's power plants combined. Modules are assembled into arrays on some kind of mounting system, which may be classified as ground mount, roof mount or pole mount. For solar parks

SECTION 60

#1732855950051

7440-442: The direct current (DC) from the solar modules to AC. Grid connected inverters must supply AC electricity in sinusoidal form, synchronized to the grid frequency, limit feed in voltage to no higher than the grid voltage and disconnect from the grid if the grid voltage is turned off. Islanding inverters need only produce regulated voltages and frequencies in a sinusoidal waveshape as no synchronisation or co-ordination with grid supplies

7560-463: The electrical grid , while off-grid systems are somewhat more common in Australia and South Korea. PV systems rarely use battery storage. This may change, as government incentives for distributed energy storage are implemented and investments in storage solutions gradually become economically viable for small systems. In the UK, the number of commercial systems using battery storage is gradually increasing as

7680-602: The fast-growing global PV market is rapidly approaching the 200 GW mark – about 40 times the installed capacity in 2006. These systems currently contribute about 1 percent to worldwide electricity generation. Top installers of PV systems in terms of capacity are currently China, Japan and the United States, while half of the world's capacity is installed in Europe, with Germany and Italy supplying 7% to 8% of their respective domestic electricity consumption with solar PV. The International Energy Agency expects solar power to become

7800-445: The power grid , in which case the energy produced by the PV array can be sold back to the utility in some sort of net metering agreement. Some utilities use the rooftops of commercial customers and telephone poles to support their use of PV panels. Solar trees are arrays that, as the name implies, mimic the look of trees, provide shade, and at night can function as street lights . Uncertainties in revenue over time relate mostly to

7920-470: The upper stage of the rocket and unfolding the solar modules, the antenna is also unfolded at the beginning of the transfer orbit to the Moon. Communication with the lunar surface is accomplished in the X band , using a high-gain 4.2 metres (14 ft) deployable parabolic antenna, the largest antenna used for a deep space exploration satellite. The large parabolic antenna provides 10 simultaneously usable X-band channels for radio traffic down to

8040-453: The weaver girl, symbolized by the star Vega ) and Niulang ( 牛郎 ; the cowherd , symbolized by the star Altair ). Despite their love for each other, their romance was forbidden, and thus they were banished to opposite sides of the heavenly river (symbolizing the Milky Way ). Once a year, on the seventh day of the seventh lunar month , a flock of magpies would form a bridge to reunite

8160-687: The "Folklore Movement" in the 1920s—the others being the Legend of the White Snake , Lady Meng Jiang , and Liang Shanbo and Zhu Yingtai —but Idema (2012) also notes that this term neglects the variations and therefore diversity of the tales, as only a single version was taken as the true version. The story of The Cowherd and the Weaver Girl and its two main characters are popular in various parts of Asia and elsewhere, with different places adopting different variations. Some historical and cross cultural similarities to other stories have also been observed. The story

8280-463: The "sunbelt" region of the planet. Large utility-scale solar parks or farms are power stations and capable of providing an energy supply to large numbers of consumers. Generated electricity is fed into the transmission grid powered by central generation plants (grid-connected or grid-tied plant), or combined with one, or many, domestic electricity generators to feed into a small electrical grid (hybrid plant). In rare cases generated electricity

8400-576: The British Standard BS 7671 , incorporating regulations relating to microgeneration and photovoltaic systems, and the US UL4703 standard, in subject 4703 "Photovoltaic Wire". A solar cable is the interconnection cable used in photovoltaic power generation. Solar cables interconnect solar panels and other electrical components of a photovoltaic system. Solar cables are designed to be UV resistant and weather resistant. They can be used within

8520-428: The Earth. When Queqiao-2 reaches a position about 200 km from the lunar surface, it will perform capture braking and enter a lunar parking orbit of 200 × 100,000 km with a period of about 10 days. Eventually, Queqiao-2 will enter a large elliptical frozen orbit of 200 × 16,000 km with a period of 24 hours, which is inclined at 62.4° to the equator. No further orbit correction maneuvers are necessary for

8640-421: The K a band transceiver . The data transmission rate for commands from the Earth to the satellite is 2000 bit/s, the telemetry data is transmitted from the satellite to the Earth at a speed of 4096 bit/s. This is twice as fast as the first Queqiao. The position is determined using a combination of the so-called Unified S-Band Technology (USB), where the distance and speed of the satellite are calculated from

8760-416: The Moon and 10 channels for traffic up to the satellite, as well as the possibility of communicating in the decimeter wave range. In the opposite direction, telemetry and payload data from the robots can be transmitted upwards at a speed of 50 kbit/s when using an omnidirectional antenna, and at 5 Mbit/s when using a parabolic antenna. The signals are then demodulated and decoded in the satellite. The K

8880-634: The Weaver Girl under the Aarne–Thompson–Uther Index ATU 400, "The Quest for the Lost Wife". The tale also holds similarities with widespread tales of the swan maiden (bird maiden or bird princess). Similar to the Chang'e space program being named after the Chinese goddess of the moon , the Queqiao and Queqiao-2 relay satellite is named after the "bridge of magpies" from the Chinese tale of

9000-530: The World Wide Web, such as OSOTF . Knowing the annual energy consumption in Kwh E d {\displaystyle E_{d}} of an institution or a family, for example of 2300Kwh, legible in its electricity bill, it is possible to calculate the number of photovoltaic panels necessary to satisfy its energy needs. By connecting to the site https://re.jrc.ec.europa.eu/pvg_tools/en/ , after selecting

9120-464: The couple shall meet only once a year. Based on some of the variants available then, Eberhard dated the story to the 5th century, although the tale seems much older, with references to it in the Huainanzi (2nd century BC). Eberhard also supposed that the fairy tale preceded the astral myth. Chinese folklorist and scholar Ting Nai-tung  [ zh ] classified the versions of The Cowherd and

9240-566: The cowherd and weaver girl. The Chang'e 4 landing site is known as Statio Tianhe , which refers to the heavenly river in the tale. The nearby far-side lunar craters Zhinyu and Hegu are named after Chinese constellations associated with the weaver girl and the cowherd. In Japan, the Engineering Test Satellite VII mission was an automated rendezvous and docking test of two satellites nicknamed "Orihime" and "Hikoboshi." Solar array A photovoltaic system , also called

9360-506: The data from the inverter or retrieve all of the data from the communicating equipment (probes, meters, etc.). Monitoring tools can be dedicated to supervision only or offer additional functions. Individual inverters and battery charge controllers may include monitoring using manufacturer specific protocols and software. Energy metering of an inverter may be of limited accuracy and not suitable for revenue metering purposes. A third-party data acquisition system can monitor multiple inverters, using

9480-446: The desired voltage ; the individual strings are then connected in parallel to allow the system to produce more current . Solar panels are typically measured under STC (standard test conditions) or PTC (PVUSA test conditions), in watts . Typical panel ratings range from less than 100 watts to over 400 watts. The array rating consists of a summation of the panel ratings, in watts, kilowatts, or megawatts. A typical 150 watt PV module

9600-438: The effects of shading and only lose the power that the shaded portion of the array would have supplied, as well as the power dissipated in the diodes. The main job of the bypass diode is to eliminate hot spots that form on cells that can cause further damage to the array, and cause fires. Sunlight can be absorbed by dust, snow, or other impurities at the surface of the module (collectively referred to as soiling ). Soiling reduces

9720-532: The energy gained by using tracking systems can outweigh the added complexity. For very large systems , the added maintenance of tracking is a substantial detriment. Tracking is not required for flat panel and low-concentration photovoltaic systems . For high-concentration photovoltaic systems, dual axis tracking is a necessity. Pricing trends affect the balance between adding more stationary solar panels versus having fewer panels that track. As pricing, reliability and performance of single-axis trackers have improved,

9840-473: The evaluation of the solar resource and to the performance of the system itself. In the best of cases, uncertainties are typically 4% for year-to-year climate variability, 5% for solar resource estimation (in a horizontal plane), 3% for estimation of irradiation in the plane of the array, 3% for power rating of modules, 2% for losses due to dirt and soiling , 1.5% for losses due to snow, and 5% for other sources of error. Identifying and reacting to manageable losses

9960-414: The fact that most of the world is not on the equator, and that the sun sets in the evening, the correct measure of solar power is insolation – the average number of kilowatt-hours per square meter per day. For the weather and latitudes of the United States and Europe, typical insolation ranges from 2.26 kWh/m /day in northern climes to 5.61 kWh/m /day in the sunniest regions. For large systems,

10080-497: The far side of the moon and the Chang'e 6 probe while still on the ground. The satellite entered its targeted elliptical orbit on 2 April after a correction midway, near-moon braking and orbital manoeuvre around the moon. It facilitates communication between Earth and lunar probes signaling China's commitment to space exploration and international cooperation. On 23 September 2024, it was discovered by independent astronomer Scott Tilley that

10200-529: The future, Queqiao-2 will also work with Chang'e 7 and Chang'e 8 to build the International Lunar Research Station . Queqiao-2 also carries two smaller Deep Space Exploration Laboratory communication satellites, Tiandu-1 and Tiandu-2 , to verify the technicality of the lunar communication and navigation constellation based on the Queqiao technology. After launch, the two satellites underwent lunar orbit insertion on 24 March 2024 at 17:43 UTC and entered

10320-404: The grid requires the transformation of DC into AC by a special, synchronizing grid-tie inverter . In kilowatt-sized installations the DC side system voltage is as high as permitted (typically 1000 V except US residential 600 V) to limit ohmic losses. Most modules (60 or 72 crystalline silicon cells) generate 160 W to 300 W at 36 volts. It is sometimes necessary or desirable to connect

10440-509: The idea was to design the relay satellite as an improved version of the Queqiao and launch it together with the Chang'e 7 probe. After a project revision, the Center for Lunar Exploration and Space Projects at the CNSA decided to launch it separately. This allowed the building of a larger variant of the relay satellite that could be launched earlier and used in the Chang'e 6 sample return mission that

10560-399: The inverter manufacturer's protocols, and also acquire weather-related information. Independent smart meters may measure the total energy production of a PV array system. Separate measures such as satellite image analysis or a solar radiation meter (a pyranometer ) can be used to estimate total insolation for comparison. Data collected from a monitoring system can be displayed remotely over

10680-423: The junction. This breakdown voltage in common cells is between 10 and 30 volts. Instead of adding to the power produced by the panel, the shaded cell absorbs power, turning it into heat. Since the reverse voltage of a shaded cell is much greater than the forward voltage of an illuminated cell, one shaded cell can absorb the power of many other cells in the string, disproportionately affecting panel output. For example,

10800-406: The large commercial and utility-scale market. Market-share for central and string inverters are about 44 percent and 52 percent, respectively, with less than 1 percent for micro-inverters. Maximum power point tracking (MPPT) is a technique that grid connected inverters use to get the maximum possible power from the photovoltaic array. In order to do so, the inverter's MPPT system digitally samples

10920-400: The life of the PV system. In one study performed in a snow-rich area ( Ontario ), cleaning flat mounted solar panels after 15 months increased their output by almost 100%. However, 5° tilted arrays were adequately cleaned by rainwater. In many cases, especially in arid regions, or in locations in close proximity to deserts, roads, industry, or agriculture, regular cleaning of the solar panels

11040-424: The light that strikes the cells, which in turn reduces the power output of the PV system. Soiling losses aggregate over time, and can become large without adequate cleaning. In 2018, the global annual energy loss due to soiling was estimated to at least 3–4%. However, soiling losses vary significantly from region to region, and within regions. Maintaining a clean module surface will increase output performance over

11160-457: The location in which to install the panels or clicking on the map or typing the name of the location, you must select "Grid connected" and "Visualize results" obtaining the following table for example relating to the city of Palermo: Using the wxMaxima program, the number of panels required for an annual consumption of 2300 kWh and for a crystalline silicon technology with a slope angle of 35°, an azimut angle of 0° and total losses equal to 21.88%

11280-417: The long run it can be clear through the long night. Full of stars, it stirs by paired palace gates, moon’s companion, it sinks by a frontier fort. Oxherd and Weaver cross it every year, and when have storms ever arisen thereon? The story of the cowherd and weaver girl spread across Asia, with different variations appearing in various languages and regions over the course of time. In Southeast Asia,

11400-505: The lovers for a single day. Though there are many variations of the story, the earliest-known reference to this famous myth dates back to a poem from the Classic of Poetry from over 2600 years ago: 詩經·小雅·大東 … 維天有漢， 監亦有光。 跂彼織女， 終日七襄。 雖則七襄， 不成報章。 睆彼牽牛， 不以服箱。 … Classic of Poetry, Lesser Court Hymns, Poem 203 … In Heavens there is the Milky Way, It looks down and

11520-452: The lower energy and power density and therefore higher weight of lead-acid batteries are not as critical as, for example, in electric transportation Other rechargeable batteries considered for distributed PV systems include sodium–sulfur and vanadium redox batteries, two prominent types of a molten salt and a flow battery, respectively. In 2015, Tesla Motors launched the Powerwall ,

11640-471: The module efficiency. However, it was recently demonstrated that, in the real-world operation, considering a larger scale photovoltaic generator, increase in wind speed can increase the energy losses, following the fluid mechanics theory, as the wind interaction with the PV generator induces air flux variations that modify the heat transfer from the modules to the air. Effective module lives are typically 25 years or more. The payback period for an investment in

11760-460: The modules partially in parallel rather than all in series. An individual set of modules connected in series is known as a 'string'. A set of series-connected "strings" is known as an "array." Photovoltaic systems are generally categorized into three distinct market segments: residential rooftop, commercial rooftop, and ground-mount utility-scale systems. Their capacities range from a few kilowatts to hundreds of megawatts. A typical residential system

11880-416: The revenue measurement point, depending on whether the credited energy production is calculated independently of the customer's energy consumption ( feed-in tariff ) or only on the difference of energy ( net metering ). These systems vary in size from residential (2–10 kW p ) to solar power stations (up to tens of MW p ). This is a form of decentralized electricity generation . Feeding electricity into

12000-479: The sad message of the shooting stars, a silent journey across the Milky Way. One meeting of the Cowherd and Weaver amidst the golden autumn wind and jade-glistening dew, eclipses the countless meetings in the mundane world. The feelings soft as water, the ecstatic moment unreal as a dream, how can one have the heart to go back on the bridge made of magpies? If the two hearts are united forever, why do

12120-469: The satellite was instead in a 119.25° 1992 × 18679 km retrograde orbit. Here is a comparison of some of the key differences of the two lunar relay satellites: The Cowherd and the Weaver Girl The Cowherd and the Weaver Girl are characters found in Chinese mythology and appear eponymously in a romantic Chinese folk tale . The story tells of the romance between Zhinü ( 織女 ;

12240-428: The shaded portion). When connected in series, the current drawn from a string of cells is no greater than the normally small current that can flow through the shaded cell, so the current (and therefore power) developed by the string is limited. If the external load is of low enough impedance, there may be enough voltage available from the other cells in a string to force more current through the shaded cell by breaking down

12360-404: The short‐circuit current, and of the maximum power to temperature changes. In this paper, comprehensive experimental guidelines to estimate the temperature coefficients. Due to the low voltage of an individual solar cell (typically ca. 0.5V), several cells are wired (see Copper in renewable energy#Solar photovoltaic power generation ) in series in the manufacture of a "laminate". The laminate

12480-470: The solar array and a number of components often summarized as the balance of system (BOS). This term is synonymous with " Balance of plant " q.v. BOS-components include power-conditioning equipment and structures for mounting, typically one or more DC to AC power converters, also known as inverters , an energy storage device, a racking system that supports the solar array, electrical wiring and interconnections, and mounting for other components. Optionally,

12600-439: The solar array's ever changing power output and applies the proper impedance to find the optimal maximum power point . Anti-islanding is a protection mechanism to immediately shut down the inverter, preventing it from generating AC power when the connection to the load no longer exists. This happens, for example, in the case of a blackout. Without this protection, the supply line would become an "island" with power surrounded by

12720-521: The solar array; however, the inverter ultimately governs the amount of AC watts that can be distributed for consumption. For example, a PV system comprising 11 kilowatts DC (kW DC ) worth of PV modules, paired with one 10-kilowatt AC (kW AC ) inverter, will be limited to the inverter's output of 10 kW. As of 2019, conversion efficiency for state-of-the-art converters reached more than 98 percent. While string inverters are used in residential to medium-sized commercial PV systems, central inverters cover

12840-415: The solar panels, the visible part of the PV system, and does not include all the other hardware, often summarized as the balance of system (BOS). PV systems range from small, rooftop-mounted or building-integrated systems with capacities ranging from a few to several tens of kilowatts to large, utility-scale power stations of hundreds of megawatts. Nowadays, off-grid or stand-alone systems account for

12960-408: The standard version of the satellite bus ). Two rotatable solar cell wings, each with two solar arrays , deliver a total output of 1350 W, the operating voltage is 30.5 V. During blackoutor eclipse period, it has accumulators with a charge storage capacity of 135 Ah . The manufacturing company assumes that Queqiao 2 will work properly for at least 8 to 10 years. Adopted from the first Queqiao,

13080-469: The story has been conflated into a Jataka tale detailing the story of Manohara , the youngest of seven daughters of the Kinnara King, who lives on Mount Kailash and falls in love with Prince Sudhana. In Korea, the story focuses on Jicknyeo, a weaver girl who falls in love with Gyeonwoo, a herder. In Japan, the story revolves around the romance between the deities, Orihime and Hikoboshi . In Vietnam,

13200-466: The story is known as Ngưu Lang Chức Nữ and revolves around the story of Chức Nữ, the weaver, and Ngưu Lang, the herder of buffalos. The Vietnamese version is also titled The Weaver Fairy and the Buffalo Boy . In the first catalogue of Chinese folktales (devised in 1937), Wolfram Eberhard abstracted a Chinese folktype indexed as number 34, Schwanenjungfrau ("The Swan Maiden"): a poor human youth

13320-588: The sun from left to right may allow seasonal adjustment up or down. Due to their outdoor usage, solar cables are designed to be resistant against UV radiation and extremely high temperature fluctuations and are generally unaffected by the weather. Standards specifying the usage of electrical wiring in PV systems include the IEC 60364 by the International Electrotechnical Commission , in section 712 "Solar photovoltaic (PV) power supply systems",

13440-508: The sunlight, it receives more light on its surface than if it were angled. Second, direct light is used more efficiently than angled light. Special anti-reflective coatings can improve solar panel efficiency for direct and angled light, somewhat reducing the benefit of tracking. Trackers and sensors to optimise the performance are often seen as optional, but they can increase viable output by up to 45%. Arrays that approach or exceed one megawatt often use solar trackers. Considering clouds, and

13560-1001: The system's overall cost, leaving the rest to the remaining BOS components and to soft costs, which include customer acquisition, permitting, inspection and interconnection, installation labor, and financing costs. A photovoltaic system converts the Sun's radiation , in the form of light, into usable electricity . It comprises the solar array and the balance of system components. PV systems can be categorized by various aspects, such as, grid-connected vs. stand alone systems, building-integrated vs. rack-mounted systems, residential vs. utility systems, distributed vs. centralized systems, rooftop vs. ground-mounted systems, tracking vs. fixed-tilt systems, and new constructed vs. retrofitted systems. Other distinctions may include, systems with microinverters vs. central inverter, systems using crystalline silicon vs. thin-film technology , and systems with modules. About 99 percent of all European and 90 percent of all U.S. solar power systems are connected to

13680-467: The systems have been installed in an increasing percentage of utility-scale projects. According to data from WoodMackenzie/GTM Research, global solar tracker shipments hit a record 14.5 gigawatts in 2017. This represents growth of 32 percent year-over-year, with similar or greater growth projected as large-scale solar deployment accelerates. Systems designed to deliver alternating current (AC), such as grid-connected applications need an inverter to convert

13800-411: The tilt angle for maximum annual array energy output. The optimization of the photovoltaic system for a specific environment can be complicated as issues of solar flux, soiling, and snow losses should be taken into effect. In addition, later work has shown that spectral effects can play a role in optimal photovoltaic material selection. For example, the spectrum of the albedo of the surroundings can play

13920-462: The two persons need to stay together—day after day, night after night? Du Fu (杜甫) (712–770) of the Tang dynasty wrote a poem about the heavenly river: 天河 常時任顯晦， 秋至輒分明。 縱被微雲掩， 終能永夜清。 含星動雙闕， 伴月落邊城。 牛女年年渡， 何曾風浪生。 The Heavenly River Most of the time it may be hidden or fully visible, but when autumn comes, it gets immediately bright. Even if covered over by faint clouds, in

14040-400: The unique option of supplying reactive power which can be advantageous in matching load requirements. Photovoltaic systems need to be monitored to detect breakdown and optimize operation. There are several photovoltaic monitoring strategies depending on the output of the installation and its nature. Monitoring can be performed on site or remotely. It can measure production only, retrieve all

14160-401: The world's largest source of electricity by 2050, with solar photovoltaics and concentrated solar thermal contributing 16% and 11% to the global demand, respectively. A grid connected system is connected to a larger independent grid (typically the public electricity grid) and feeds energy directly into the grid. This energy may be shared by a residential or commercial building before or after

14280-456: The world, mostly in Europe, with 1.4 million systems in Germany alone – as well as North America with 440,000 systems in the United States. The energy conversion efficiency of a conventional solar module increased from 15 to 20 percent since 2004 and a PV system recoups the energy needed for its manufacture in about 2 years. In exceptionally irradiated locations, or when thin-film technology

14400-461: Was also launched in 2024 to the Apollo crater on the far side of the Moon . Although the first Queqiao can provide the unique function of relaying constant communications to and from the far side of the Moon, aided by Chinese Deep Space Network , its halo orbits around the Earth-Moon L 1 and L 2 were inherently unstable and requires the satellite to consumes 80 g (2.8 oz) of fuel for

#50949