Photovoltaic system

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The photovoltaic system, also PV systems or solar systems , is a power system designed to supply solar power that can be used using photovoltaics. It consists of arranging several components, including solar panels to absorb and convert sunlight into electricity, solar inverters to convert electric current from DC to AC, as well as installation, cabling, and other electrical accessories to regulate the working system. It can also use a solar tracking system to improve the overall performance of the system and include an integrated battery solution, as the prices for storage devices are expected to decrease. In fact, a solar array only includes the solar panel ensemble, the visible part of the PV system, and excludes all other hardware, often summarized as system balance (BOS). In addition, PV systems convert light directly into electricity and should not be confused with other technologies, such as concentrated solar power or solar heat, used for heating and cooling.

PV systems range from small, integrated roof or building systems with capacities ranging from several to several tens of kilowatts, to utility-scale power plants of hundreds of megawatts. Currently, most PV systems are connected to the network, while off-grid systems or stand-alone systems cover only a small fraction of the market.

Operating quietly and without moving parts or environmental emissions, PV systems have evolved from being niche market applications into adult technologies used for mainstream power generation. The roof system recovers the energy invested for its manufacture and installation within 0.7 to 2 years and generates about 95 percent clean renewable energy for 30 years service life.

Due to exponential photovoltaic growth, prices for PV systems have declined rapidly in recent years. However, they vary by market and system size. By 2014, the price for a 5 kilowatt residential system in the United States is about $ 3.29 per watt, while in the highly penetrated German market, the price for roof systems up to 100 kW decreases to EUR1,24 per watt. Currently, solar PV modules contribute less than half the overall cost of the system, leaving the rest to the remaining BOS components and soft costs, which include customer acquisition, licensing, inspection and interconnection, installation labor and financing costs.

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The photovoltaic system converts solar radiation into usable electricity. It consists of a solar array and a balance of system components. PV systems can be categorized based on various aspects, such as, vs. stand-alone networking systems, systems integrated with building versus shelf, vs. housing systems. utilities, distributed systems vs. centered, roof vs. land-mounted systems, vs. tracking fixed-tilt systems, and new vs. built systems. retrofit. Other differences may include, systems with microinverters vs. central inverters, systems that use crystalline silicon vs. thin-film technology, and systems with modules from Chinese vs. manufacturers. Europe and the US.

About 99 percent of all Europe and 90 percent of all US solar systems are connected to the power grid, while the off-grid system is somewhat more common in Australia and South Korea. PV systems rarely use battery storage. This may change immediately, as government incentives for distributed energy storage are being implemented and investment in storage solutions gradually becomes economical for small systems. The solar array of typical residential PV systems is rack-mounted on the roof, rather than integrated into the roof or facade of buildings, as these are significantly more expensive. Utility-scale solar power plants are installed on the ground, with fixed-tilt solar panels instead of using expensive tracking devices. Silicon crystals are the main ingredients used in 90 percent of solar modules produced worldwide, while rival thin films have lost market share in recent years. About 70 percent of all solar cells and modules are manufactured in China and Taiwan, leaving just 5 percent for European and US producers. The installed capacity for both, small roof systems and large solar power plants is growing rapidly and in the same section, although there is an important trend towards utility-scale systems, as the focus on new installations shifts from Europe to brighter areas, such as Sunbelt in the US , which is less at odds with solar farms installed on the ground and the cost effectiveness is more emphasized by the investors.

Driven by technological advances and an increase in manufacturing scale and sophistication, the cost of photovoltaics continues to decline. There are several million PV systems distributed worldwide, especially 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 conventional solar modules increases from 15 to 20 percent over 10 years and the PV system regains the energy needed for its manufacture in about 2 years. In a highly irradiated location, or when thin film technology is used, the so-called energy return time decreases to a year or less. Net metering and financial incentives, such as preferential feed-in rates for electricity generated by the sun, also strongly support the installation of PV systems in many countries. The flattened power costs of large-scale PV systems have become competitive with conventional electricity sources in the geographic list of expansion areas, and grid parity has been achieved in about 30 different countries.

By 2015, the fast-growing global PV market is approaching 200 GW - about 40 times the installed capacity of 2006. The current photovoltaic system contributes about 1 percent to power plants worldwide. Top installers of PV systems in terms of current capacity are 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 domestic electricity consumption with solar PV. The International Energy Agency expects solar power to become the world's largest power source by 2050, with solar photovoltaic and concentrated solar heat contributing 16% and 11% respectively to global demand.

Network connection

Network-connected systems connect to larger independent networks (usually public power grids) and channel energy directly to the grid. This energy can be divided by residential or commercial buildings before or after the revenue measurement point. The difference is whether the credited energy production is calculated independently of the customer's energy consumption (feed-in tariff) or only on the energy difference (net measurement). Grid-connected systems vary in size from housing (2-10 kW _p ) to solar power generation (up to 10 million MW _p ). This is a decentralized power generation. Power supply to the network requires DC transformation to AC by a synchronous special grid-tie inverter. In kilowatt-sized installations, DC side system voltages are as high as permitted (usually 1000V except for US 600V housings) to limit ohmic losses. Most modules (60 or 72 crystalline silicon cells) produce 160 W to 300 W at 36 volts. Sometimes it is necessary or desirable to connect partial modules in parallel rather than all in series. A set of connected modules in series is known as 'string'.

System Scale

Photovoltaic systems are generally categorized into three distinct market segments: residential rooftops, commercial rooftops, and utility-scale systems on land. Their capacities range from several kilowatts to hundreds of megawatts. Typical residential systems are about 10 kilowatts and are mounted on sloping roofs, while commercial systems can reach megawatts and are generally mounted on low slopes or even flat roofs. Although the roof-mounted system is small and displays higher cost per watt than large utility-scale installations, they take into account the largest share in the market. However, there is a growing trend toward larger utility-scale power plants, especially in the "sunbelt" region of the planet.

Utility-scale

Large scale utility-scale solar or garden gardens are power plants and capable of providing energy supplies to a large number of consumers. The electricity generated is fed into a transmission network powered by central (network-connected or network-connected) power plants, or combined with one or more domestic power stations to be inserted into a small power grid (hybrid plant). In rare cases the generated electricity is stored or used directly by islands/stand-alone plants. PV systems are generally designed to ensure the highest energy yield for a particular investment. Some major photovoltaic power plants such as the Sun Star, Waldpolenz Solar Park and Topaz Solar Farm cover tens or hundreds of hectares and have power output of up to hundreds of megawatts.

Roof, mobile, and portable

Small PV systems are capable of providing enough AC power to power a single home, or even an isolated device in the form of AC or DC power. For example, military and civilian observation satellites, streetlights, construction and traffic signs, electric cars, solar powered tents, and electric planes may contain integrated photovoltaic systems to provide a primary or additional power source in the form of AC or DC power, depending on design demand and strength. By 2013, roof systems account for 60 percent of installations worldwide. However, there is a tendency away from the roof and towards a utility-scale PV system, as the focus of new PV installations also shifts from Europe to countries in the region where solar shelter is on the planet where opposition to solar farms installed on the ground is less emphasized.

Portable and cellular PV systems provide power apart from utility connections, for off the grid operation. Such systems are very commonly used in recreational vehicles and existing boat retailers specializing in these applications and products that are specifically targeted to them. Since recreational vehicles typically carry batteries and operate lighting and other systems at nominal 12-volt DC power, PV RV systems typically operate within the selected voltage range to directly charge 12-volt batteries, and the addition of a PV system requires only a panel , charge controllers, and cables.

Building-integrated

In urban and suburban areas, photovoltaic arrangements are usually used on roofs to supplement power usage; often the building will have a connection to the power grid, in which case the energy generated by the PV array can be resold to the utility in a kind of net measurement agreement. Some utilities, such as Solvay Electric in Solvay, NY, use commercial rooftop customers and telephone poles to support the use of PV panels. The solar tree is an array that, as the name implies, mimics the look of the tree, gives shade, and at night can serve as a streetlight.

Performance

Uncertainty of income over time is largely related to the evaluation of solar resources and the performance of the system itself. In the best case, uncertainty is usually 4% for year-to-year climate variability, 5% for solar resource estimation (in horizontal plane), 3% for irradiation estimation in array field, 3% for module rating power, 2% for dirt loss and defilements, 1.5% for losses due to snow, and 5% for other sources of error. Identifying and reacting to manageable losses is critical to O & M revenue and efficiency. Monitoring of array performance can be part of contractual agreements between line owners, builders, and utilities that purchase the energy generated. More recently, the method for making "synthetic days" using available weather data and verification using the Solar Field Open Fields allows to predict the performance of photovoltaic systems with high accuracy. This method can be used to then determine the mechanism of loss on a local scale - such as from snow or surface coating effects (eg hydrophobic or hydrophilic) to dirt or loss of snow. (Although in heavy snow environments with severe soil disturbance can cause annual losses from snow by 30%.) Access to the Internet has enabled a further increase in energy and communications monitoring. Custom systems are available from a number of vendors. For solar PV systems that use microinverters (DC panel level to AC conversion), module power data is automatically provided. Some systems allow setting performance settings that trigger phone/email/text alert when the limit is reached. This solution provides data for system owners and installers. The installer can monitor multiple installations remotely, and glimpse status from all installed bases.

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Components

The photovoltaic system for residential, commercial, or industrial energy supply consists of a solar panel arrangement and a number of components that are often summarized as system balances (BOS). This term is identical with "Balance of plant" q.v. BOS components include equipment and power conditioning structures for installation, usually one or more DC power converters to the AC, also known as inverters, energy storage devices, rack systems that support the solar array, power lines and interconnects, and mounting for other components.

Optionally, the balance of the system may include any or all of the following: a source of renewable energy credit income, a maximum power point tracker (MPPT), battery and charging system, GPS solar tracker, energy management software, solar radiation sensor, anemometer, or accessory-specific tasks designed to meet the system owner's specific requirements. In addition, the CPV system requires optical lenses or mirrors and sometimes cooling systems.

The terms "solar array" and "PV systems" are often wrongly used interchangeably, despite the fact that solar arrays do not cover the entire system. In addition, "solar panels" are often used as synonyms for "solar modules" , even though the panel consists of a series of several modules. The term "solar system" is also a common misnomer for PV systems.

Solar array

Conventional c-Si solar cells, usually connected in series, are encapsulated in solar modules to protect them from the weather. This module consists of tempered glass as a cover, soft and flexible encapsulant, rear backsheet made of weathering material and fire retardant and aluminum frame around the outer edge. Electricity is connected and mounted on a support structure, the solar module builds a series of modules, often called solar panels. The solar array consists of one or many such panels. A photovoltaic array, or a solar array, is a collection of connected solar modules. The power that a single module can generate is rarely enough to meet the requirements of a home or business, so modules are linked together to form an array. Most PV arrays use inverters to convert DC power generated by the module into alternating current that can turn on lights, motors, and other loads. Modules in a PV array are usually first connected in series to obtain the desired voltage; individual strings are then connected in parallel to allow the system to produce more current. Solar panels are usually measured under STC (standard test conditions) or PTC (PVUSA test conditions), in watts. General panel ratings range from less than 100 watts to over 400 watts. The array ranking consists of the sum of the panel ratings, in watts, kilowatts, or megawatts.

Module and efficiency

The "150 watts" PV module measures about one square meter. Such modules are expected to produce 0.75 kilowatt-hour (kWh) daily, on average, after calculating weather and latitude, for insolation 5 hours of sun/day. In the last 10 years, the average efficiency of wafer-based crystalline silicon modules increased from about 12% to 16% and CdTe module efficiency increased from 9% to 13% over the same period. Output modules and life are degraded by rising temperatures. Allow ambient air to flow overhead, and if possible behind, PV modules reduce this problem. Effective module life is usually 25 years or more. The payback period for investments in PV solar installations varies considerably and is usually less useful than the calculation of return on investment. Although usually counted between 10 and 20 years, the period of financial return can be much shorter with incentives.

Due to the low voltage of individual solar cells (usually around 0.5 V), some cable cells (also see copper used in PV systems) in series in the manufacture of "laminate". Laminates are assembled into weather-resistant protective cages, thus creating photovoltaic modules or solar panels. The modules can then be assembled into photovoltaic arrays. In 2012, solar panels available to consumers can have an efficiency of up to about 17%, while commercially available panels can reach up to 27%. It has been noted that groups from the Fraunhofer Institute for Solar Energy Systems have created cells that can achieve 44.7% efficiency, which makes scientists' expectations to reach a 50% efficiency threshold are far more feasible.

Shading and dirt

The electrical output of photovoltaic cells is very sensitive to shadows. The effects of this shadow are well known. When even a small cell, module, or arrangement is shaded, while the output is in the sun, the output falls dramatically because of the internal 'short circuit' (electrons reversing direction through the shaded part of the p-n connection). If the current taken from the cell string circuit is no larger than the current that the shaded cell can generate, the current (and also power) developed by the string is limited. If sufficient voltage is available from the rest of the cells in the string, the current will be forced through the cell by splitting the intersections in the shaded part. The voltage of this damage in the common cells is between 10 and 30 volts. Instead of adding the power generated by the panel, the shaded cell absorbs power, turning it to heat. Since the shaded turns of the cell are much larger than the forward voltage of the illuminated cell, a shaded cell can absorb the power of many other cells in the string, disproportionately affecting the output panel. For example, a shaded cell can fall 8 volts instead of adding 0.5 volts, at a certain current rate, thus absorbing the power generated by the other 16 cells. Therefore, it is important that the PV installation is not shaded by trees or other obstructions.

Several methods have been developed to determine shading losses from trees to PV systems in both large areas using LiDAR, but also at the level of individual systems using sketchup. Most modules have a diode bypass between each cell or cell string that minimizes the shadow effect and only loses the strength of the shaded part of the shading. The main task of the bypass diode is to remove the hot spots formed on cells that can cause further damage to the array, and cause a fire. Sunlight can be absorbed by dust, snow, or other dirt on the surface of the module. This can reduce the light that attacks the cell. In general, the losses accumulated during the year are small even for Canadian locations. Maintaining a clean module surface improves output performance over the life of the module. Google found that cleaning the solar panels that were installed flat after 15 months increased their output by almost 100%, but 5% of the array was tilted quite cleaned by rainwater.

Insolation and energy

Solar insulation consists of direct, spreading, and reflected radiation. The absorption factor of PV cells is defined as the fraction of incident solar radiation absorbed by the cell. At noon on a cloudless day at the equator, the power of the sun is about 1 kW/mÃ,², on the Earth's surface, to planes perpendicular to sunlight. Thus, PV arrays can track the sun through each day to increase energy gathering. However, the tracking device adds cost, and requires maintenance, making it more common for PV arrays to have a fixed mount that tilts the array and faces the afternoon sun (roughly southward in the northern or northern hemisphere in the southern hemisphere). Tilt angles, from horizontal, may vary for the season, but if fixed, should be set to provide optimal array output during peak electrical demand sections of the year typical for stand-alone systems. The slope angle of this optimum module is not always identical to the slope angle for maximum annual array energy output. Optimization of photovoltaic systems for a particular environment can be complicated because of the problem of solar flux, dirtiness, and snow loss should be put into effect. In addition, recent work shows that spectral effects can play a role in the selection of optimal photovoltaic materials. For example, spectral albedo can play an important role in the output depending on the surface around the photovoltaic system and the type of solar cell material. For weather and latitudes of the United States and Europe, the typical insolation ranges from 4 kWh/mÃ,²/day in northern climates to 6.5 â € <â € Mounting

The modules are assembled into several types of mounting systems, which can be classified as ground mount, roof mount or pole mount. For solar parks, large shelves are installed on the ground, and modules are mounted on the shelves. For buildings, many different shelves have been designed for sloping roofs. For flat roofs, shelves, bins and building integrated solutions are used. Shelves of solar panels mounted on poles can be still or move, see Trackers below. The pole side pole is suitable for situations where the pole has something else mounted on it, such as a lamp or antenna. Pole mounting raises what should be a ground mount extension over shadows and livestock, and can meet the electrical code requirements regarding inaccessibility of exposed wires. The panel mounted on the pole is open for more cooling air at the bottom, which improves performance. Various top shelf poles can be shaped into carport parking or other shade structures. A rack that does not follow the sun from left to right allows seasonal adjustments to rise or fall.

Cable

Due to their outdoor use, the solar cables are specifically designed to withstand UV radiation and extremely high temperature fluctuations and are generally unaffected by the weather. A number of standards determine the use of electrical cables in PV systems, such as IEC 60364 by the International Electrotechnical Commission, in section 712 "photovoltaic solar power supply system (PV)" , British Standard BS 7671, incorporating rules relating to systems microgeneration and photovoltaic, and US UL4703 standard, in the 4703 subject "Photovoltaic Wire" .

Tracker

The solar tracking system tilts the solar panels throughout the day. Depending on the type of tracking system, this panel is directed directly to the sun or the brightest area of ​​the sky that is partially covered by clouds. Trackers greatly improve morning and afternoon performance, increasing the total amount of power generated by the system by about 20-25% for single axis trackers and about 30% or more for double axis trackers, depending on latitude. Trackers are effective in areas that receive most of the sun directly. In diffuse light (ie under cloud or fog), the tracking has little or no value. Since most concentrated photovoltaic systems are highly sensitive to sunlight angles, the tracking system allows them to produce useful power for more than one brief period each day. Tracking systems improve performance for two main reasons. First, when the solar panel is perpendicular to the sunlight, it receives more light on its surface than if it is tilted. Second, direct light is used more efficiently than angled light. Special anti-reflective coatings can increase the efficiency of solar panels for direct and angular light, somewhat reducing tracking benefits.

Trackers and sensors for optimizing performance are often seen as optional, but tracking systems can increase viable output by up to 45%. PV arrays that are close to or exceeding one megawatt often use a solar tracker. Accounting for the cloud, and the fact that most of the world is not on the equator, and that the sun sets at night, the exact size of solar power is insolation - the average number of kilowatt-hours per square meter per day. For weather and latitudes of the United States and Europe, the typical insolation ranges from 2.26 kWh/mÃ,²/day in northern climates to 5.61 kWh/mÃ,²/day in the brightest region.

For large systems, the energy obtained by using a tracking system can exceed the additional complexity (trackers can increase efficiency by up to 30% or more). For very large systems, additional maintenance tracking is a big disadvantage. Tracking is not required for flat panels and low-concentration photovoltaic systems. For high-concentration photovoltaic systems, double axis tracking is a must. Price trends affect the balance between adding more stationary solar panels compared to fewer tracked panels. When the price of solar panels drops, the tracker becomes a less attractive option.

Inverter

Systems designed to deliver alternating current (AC), such as network-connected applications require an inverter to convert the direct current (DC) from a solar module into an AC. The network-connected inverter must provide AC power in the form of a sinusoidal, synchronized to the grid frequency, limiting the feed in voltage to no higher than the grid voltage and disconnecting from the grid if the grid voltage is turned off. Islanding inverters only need to generate a voltage and frequency set in a sinusoidal wave because there is no need for synchronization or coordination with the network supply.

A solar inverter can connect to a series of solar panels. In some installations, solar micro-inverters are connected to each solar panel. For safety reasons, circuit breakers are provided both on the AC and DC sides to allow maintenance. The AC output can be connected through the power meter to the public network. The number of modules in the system determines the total DC wattage that can be generated by the solar array; however, the inverter ultimately sets the amount of AC watts that can be distributed for consumption. For example, a PV system consisting of 11 kilowatts of DC (kW _DC ) worth of PV modules, paired with a 10-kilowatt AC (kW _AC ) inverter, will be limited to output 10 kW inverter. By 2014, conversion efficiency for advanced converters has reached more than 98 percent. While string inverters are used in housing for medium-sized commercial PV systems, central inverters include commercial markets and large utility scales. The market share for central and string inverters is about 50 percent and 48 percent, respectively, leaving less than 2 percent to micro-inverters.

Tracking of maximum power point (MPPT) is a technique used inverter connected grid to get the maximum possible power from photovoltaic arrays. To do so, the MPPT system inverters digitally takes a sample of the constantly changing solar array power output and implements the proper resistance to find the maximum power point .

Anti-islanding is a protection mechanism that immediately turns off the inverter that prevents it from generating AC power when the connection to the load ceases to exist. This happens, for example, in case of a power outage. Without this protection, the supply lines would be "islands" with forces surrounded by a "sea" of unpowered paths, as the array of solar panels continues to transmit DC power during power outages. Islanding is a hazard to utility workers, who may not be aware that the AC circuit is still powered, and can prevent automatic reset of the device.

Battery

Although still expensive, more and more PV systems use rechargeable batteries to store surplus for later use at night. The batteries used for grid storage also stabilize the power grid by leveling the peak load, and play an important role in the smart grid, as they can fill during low demand periods and feed energy stored into the grid when demand is high.

Common battery technologies used in current PV systems include acid-lead battery valves - modified versions of conventional lead-acid batteries, nickel-cadmium and lithium-ion batteries. Compared to other types, lead-acid batteries have a shorter life span and lower energy density. However, due to its high reliability, low self-discharge and low investment and maintenance costs, they are currently the main technology used in small residential PV systems, since lithium-ion batteries are still being developed and about 3.5 times as expensive lead-acid batteries. Furthermore, as storage devices for stationary PV systems, lower energy and power density and therefore higher weights of lead-acid batteries are not as important as, for example, in electrical transport. Other rechargeable batteries being considered for distributed PV systems include sodium. red-sulfur and vanadium batteries, the two main types of molten salt and flow batteries, respectively. By 2015, the Tesla motor launches Powerwall, a rechargeable lithium-ion battery with the aim of revolutionizing energy consumption.

PV systems with integrated battery solutions also require charge controllers, since the range of voltages and currents from the solar array require constant adjustments to prevent excessive filling damage. Basic charge controllers can only turn on and off PV panels, or can measure the required energy pulses, a strategy called PWM or pulse-width modulation. More advanced cost controllers will combine MPPT logic into their battery charging algorithms. The charge controller can also divert energy to several destinations other than charging the battery. Instead of just turning off the free PV energy when not required, the user can choose to heat air or water after the battery is full.

Monitoring and measurement

Measurements should be able to collect energy units in either direction or two meters should be used. Many meters accumulate bidirectional, some systems use two meters, but a direct meter (with a detent) will not collect energy from the resulting feed into the grid. In some countries, for the installation of more than 30 kW _p frequency and the voltage monitor with the termination of all phases is required. This is done where more solar power is generated than the utility can accommodate, and the excess can not be exported or stored. Network operators must historically provide transmission lines and generating capacity. Now they should also provide storage. This is usually hydro-storage, but other storage means are used. Initially storage is used so that baseload generators can operate at full output. With variable renewable energy, storage is needed to enable power generation whenever it is available, and consumption whenever it is needed.

The two variables a network operator has is storing power for when is required, or sending it to where is required. If both fail, installation of more than 30kWp can automatically die, although in practice all inverters maintain voltage regulation and stop supplying power if the load is inadequate. Network operators have the option to limit the excess generation of large systems, although this is more often done with wind power than solar power, and generates substantial revenue losses. The three phase inverter has a unique option to supply reactive power that can be advantageous in meeting load requirements.

Photovoltaic systems need to be monitored to detect damage and optimize their operations. There are several photovoltaic monitoring strategies depending on the output of the installation and its nature. Monitoring can be done on the site or remotely. It can measure production only, retrieve all data from inverter or retrieve all data from communications equipment (probe, meter, etc.). Monitoring tools can be dedicated to supervision only or offer additional functionality. Individual inverters and battery charge controllers may include monitoring using manufacturer-specific protocols and software. The energy measurements of the inverters may have limited accuracy and are not suitable for the purpose of measurement of income. Third party data acquisition systems can monitor multiple inverters, use inverter factory protocols, and also obtain weather related information. The independent intelligent meter can measure the total energy production of the PV array system. Separate steps such as satellite image analysis or solar radiation meter (pyrometer) can be used to estimate total insolation as a comparison. Data collected from monitoring systems can be displayed remotely via the World Wide Web, such as OSOTF.

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Other systems

This section includes highly specialized and unusual or still new technologies emerging with limited significance. However, the standalone or off-grid system takes a special place. They were the most common type of system during the 1980s and 1990s, when PV technology was still very expensive and a pure niche market of small-scale applications. Only in places where there is no power grid available, they are economically viable. Although stand-alone new systems are still in use around the world, their contribution to overall installed photovoltaic capacity is declining. In Europe, off-grid systems account for 1 percent of installed capacity. In the United States, they account for about 10 percent. Off-grid systems are still common in Australia and South Korea, and in many developing countries.

CPV

Photovoltaic concentrators (CPV) and high concentrator photovoltaic (HCPV) systems use optical lenses or curved mirrors to concentrate sunlight into small but highly efficient solar cells. In addition to optical concentrates, CPV systems sometimes use solar and cooling system trackers and are more expensive.

Especially the HCPV system is best suited in locations with high solar radiation, sunlight concentrating up to 400 times or more, with an efficiency of 24-28 percent, over the regular system. Various designs of CPV and HCPV systems are commercially available but not very common. However, ongoing research and development is ongoing.

CPV is often confused with CSP (concentrated solar power) that does not use photovoltaics. Both technologies support locations that receive a lot of sunlight and directly compete with each other.

Hybrid

The hybrid system combines PV with another generation form, usually a diesel generator. Biogas is also used. Another form of generation may be the type that can modulate the power output as a demand function. However, more than one form of renewable energy can be used for example wind. Photovoltaic power generation works to reduce the consumption of non-renewable fuels. Hybrid systems are most commonly found on the islands. Pellworm Island in Germany and Kythnos Island in Greece are well known examples (both combined with wind). The Kythnos plant has reduced diesel consumption by 11.2%.

By 2015, a case study conducted in seven countries concludes that in all cases, generating costs can be reduced by mini-network hybridization and isolated grids. However, the cost of financing for such hybrids is very important and highly dependent on the ownership structure of power plants. While cost reductions for state-owned utilities can be significant, the study also identifies the economic benefits of being insignificant or even negative for non-public utilities, such as independent power producers.

There is also a recent work showing that the penetration limit of PV can be increased by spreading the distributed network of PV CHP hybrid systems in the US Temporal distribution of solar flux, electrical and heating requirements for representative US single family residence is analyzed and the results clearly show that the hybridization of CHP with PV could enable deployment of additional PV above what is possible with a conventional centralized power generation system. This theory is confirmed by numerical simulation using per second solar flux data to determine that the battery reserves required to provide such a hybrid system are possible with relatively small and inexpensive battery systems. In addition, large CHP PV systems are possible for institutional buildings, which again provide intermittent PV backup and reduce CHP runtime.

• PVP systems (hybrid PV/T), also known as photovoltaic thermal hybrid solar collector convert solar radiation into thermal and electrical energy. Such a system incorporates a solar module (PV) with a complementary solar thermal collector.
• CPVT system . The concentrated thermal photovoltaic hybrid system (CPVT) is similar to the PVT system. It uses concentrated photovoltaic (CPV) instead of conventional PV technology, and combines it with a solar thermal collector.
• CPV/CSP System . The new CPV/CSP solar hybrid system has been proposed recently, incorporating a photovoltaic consorter with a concentrated non-PV solar power technology (CSP), or also known as concentrated solar thermal.
• PV diesel system . It combines photovoltaic systems with diesel generators. Combinations with other renewable energies are possible and include wind turbines.

Floating solar array

Floating solar arrays are PV systems floating on the surface of drinking water reservoirs, quarry lakes, irrigation or remediation channels and tailings pools. This system is called "floatovoltaics" when used only for electricity production or "aquavoltaics" when the system is used to improve fisheries synergistically. A small number of such systems exist in France, India, Japan, South Korea, the United Kingdom, Singapore, and the United States.

The system is said to have advantages over photovoltaics on land. Land costs are more expensive, and there are fewer rules and regulations for structures built on bodies of water not used for recreation. Unlike most ground-based solar generators, floating arrays can be unobtrusive because they are hidden from public view. They achieve higher efficiency than PV panels on land, because water cools the panels. The panel has a special coating to prevent rust or corrosion.

In May 2008, Far Niente Winery in Oakville, California, spearheaded the world's first floatovoltaic system by installing 994 solar PV modules with a total capacity of 477 kW to 130 pontoons and floating them in a winemaking irrigation pool. The main benefit of such a system is that it avoids the need to sacrifice valuable land that can be used for other purposes. In the case of Far Niente Distillery, it saved three quarters of an acre that should be required for land-based systems. Another benefit of the floatovoltaic system is that the panels are kept at colder temperatures than on land, leading to higher solar conversion efficiency. Floating PV arrays also reduce the amount of water lost through evaporation and inhibit algal growth.

A floating PV farm utility scale began to be built. Kyocera multinational electronics and ceramics producers will develop the world's largest livestock, 13.4 mW in reservoirs above Yamakura Dam in Chiba Prefecture using 50,000 solar panels. Salt-resistant floating brackets are also considered for marine use, with experiments in Thailand. By far the largest floatovoltaic project announced is a 350 MW power plant in the Brazilian Amazon region.

Direct current grid

DC gratings are found in electric powered transportation: tram rail and trolleybuses. Several pilot mills for such applications have been built, such as the tram depot at Hannover Leinhausen, using photovoltaic and Geneva contributor (Bachet de Pesay). 150 150 kW _p The Geneva site distributes 600V DC directly to the tram/trolleybus power grid while previously providing about 15% of electricity at its opening in 1999.

Standalone

Stand-alone systems or outside the network are not connected to the power grid. Standalone systems vary greatly in size and application from watches or calculators to remote buildings or spacecraft. If the load must be supplied independently of the solar insolation, the resulting power is stored and supported by the battery. In non-portable applications where weight is not a problem, as in buildings, lead acid batteries are most commonly used because of their low cost and tolerance for abuse.

The charge controller can be incorporated into the system to avoid battery damage by overcharging or discharging. It can also help optimize the production of solar arrays using the maximum power point tracking technique (MPPT). However, in simple PV systems where the PV module voltage is matched with battery voltage, the MPPT electronic usage is generally considered unnecessary, since the battery voltage is stable enough to provide near-maximum power collection of the PV module. In small devices (eg calculators, parking meters) only direct current (DC) is consumed. In larger systems (eg buildings, long-distance water pumps), air conditioning is usually required. To convert DC from module or battery to AC, an inverter is used.

The cost of producing photovotaic cells has come down due to economies of scale in production and technological advances in manufacturing. For large-scale installations, a price below $ 1.00 per watt is common in 2012. A 50% price drop has been achieved in Europe from 2006 to 2011 and there is the potential to lower generating costs by 50% by 2020. Crystal silicon solar cells has been largely superseded by cheaper multicrystalline silicon solar cells, and thin film silicon solar cells have also been developed recently with lower production costs. Although they reduce the energy conversion efficiency of single crystal "siwafers", they are also easier to produce at lower cost.

The table below shows the total cost in US cents per kWh of electricity generated by the photovoltaic system. The title line on the left shows the total cost, per kilowatt peak (kW _p ), photovoltaic installation. The cost of photovoltaic systems has decreased and in Germany, for example, is reported to have fallen to USD 1389/kW _p by the end of 2014. The column headings at the top refer to the annual energy output at the expected kWh of each kW installed < sub> p . This varies by geographical area because the average insulation depends on the average turbidity and the thickness of the atmosphere through which the sun travels. It also depends on the path of the sun relative to the panel and the horizon. Panels are usually mounted at an angle based on latitude, and often they are seasonally adjusted to meet changes in the sun's declination. Solar tracking can also be used to access more perpendicular sunlight, thereby increasing the total energy output.

The value calculated in the table reflects the total cost in the cents per kWh generated. They assume a total capital cost of 10% (eg 4% interest rate, 1% operational and maintenance costs, and a 20-year capital expenditure depreciation). Typically, photovoltaic modules have a 25 year warranty.

System cost 2013

In the 2014 edition of the "Road Map Technology: Solar Photovoltaics Energy" report, the International Energy Agency (IEA) published prices in US $ per watt for residential, commercial and utility PV systems for eight major markets by 2013.

Learning curve

The photovoltaic system shows a learning curve in terms of Levelized Cost of Electricity (LCOE), reducing the cost per kWh by 32.6% for every doubling of capacity. From LCOE data and the cumulative installed capacity of the International Renewable Energy Agency (IRENA) from 2010 to 2017, the learning curve equations for photovoltaic systems are given as

${\ displaystyle LCOE_ {photovoltaic} = 151.46 \, Kapasitas ^ {- 0,57}}  ÂÂ$

• LCOE: menaikkan biaya listrik (dalam USD/kWh)
• Kapasitas: kapasitas terpasang kumulatif dari sistem fotovoltaik (dalam MW)

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Peraturan

Standardisasi

Increasing the use of photovoltaic systems and photovoltaic power integration into existing supply and distribution structures and techniques enhance the value of common standards and definitions for photovoltaic components and systems. This standard is developed at the International Electrotechnical Commission (IEC) and applies to the efficiency, durability and safety of cells, modules, simulation programs, plugs and plug cables, mounting systems, overall inverter efficiency etc.

Planning and allowing

While article 690 of the National Electrical Code provides general guidelines for the installation of photovoltaic systems, these guidelines may be replaced by local laws and regulations. Often permits are required which require the submission of plans and structural calculations before work can commence. In addition, many locals require work to be done under the guidance of a licensed electrician. Check with local City/County AHJ (Jurisdictional Authority) to ensure compliance with applicable laws or regulations.

In the United States, the Authority Having Jurisdiction (AHJ) will review the design and issue permits, before construction can commence legally. Electrical installation practices must comply with the standards set out in the National Electrical Code (NEC) and be checked by AHJ to ensure compliance with building codes, electrical codes, and fire safety codes. Jurisdiction may require that equipment has been tested, certified, registered, and labeled by at least one of the National Recognized Testing Laboratories (NRTL). Although the installation process is complicated, a list of the latest solar contractors shows the majority of installation companies established since 2000.

National rules

United Kingdom

In the UK, PV installations are generally regarded as permissible development and do not require planning permission. If the property is registered or in a designated place (National Park, Extraordinary Natural Beauty Area, Special Scientific Interest Site or Norfolk Broads) then planning permission is required.

United States

In the US, many areas require permission to install photovoltaic systems. The grid-bound system usually requires a licensed electrician to make connections between the system and the cable network connected to the building. Qualified installers are located in almost every state. The State of California bans homeowners association limiting solar devices.

Spanish

Although Spain generates about 40% of its electricity through photovoltaic and other renewable sources of energy, and cities like Huelva and Seville boast nearly 3,000 hours of sunshine per year, Spain has been levying the solar tax to account for the debts created by investments made by the Spanish government. Those who are not connected to the network can face a fine of 30 million euros ($ 40 million USD).

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Limitations

• Pollution and Energy in PV Production

PV has become a well-known method for generating clean emission-free electricity. PV systems are often fabricated PV modules and inverters (converting DC to AC). The PV modules are mainly made of PV cells, which have no fundamental difference in the material for making computer chips. The process of producing PV cells (computer chips) is energy intensive and involves highly toxic and environmental toxic chemicals. There are several PV factories around the world that produce PV modules with energy produced from PV. This measure greatly reduces the carbon footprint during the manufacturing process. Managing chemicals used in the manufacturing process is subject to local factory laws and regulations.

• Impact on Electrical Network

With the increasing levels of roof photovoltaic systems, the flow of energy becomes 2 directions. When there are more local generations than consumption, electricity is exported to the grid. However, the power grid is traditionally not designed to handle two-way energy transfers. Therefore, some technical problems may occur. For example, in Queensland Australia, there are more than 30% of households with roofing PV by the end of 2017. The very popular California duck curve appears very often for many communities from 2015 onwards. The problem of excess voltage can come out because electricity is flowing from this PV household back to the network. There are solutions to manage more voltage problems, such as setting the power factor of PV inverter, new voltage and energy control equipment at power distributor level, re-conductor power cable, demand side management, etc. There are often limitations and costs associated with this solution.

• Implications for Electricity Billing and Energy Investment

There is no silver bullet in electricity or energy demand and bill management, because the customer (site) has a different specific situation, eg. different comfort/convenience requirements, different electricity rates, or different usage patterns. Electricity rates may have several elements, such as daily access and meter costs, energy costs (based on kWh, MWh) or peak demand costs (eg prices for the highest 30min energy consumption in a month). PV is a promising choice to reduce energy costs when electricity prices are high and continue to rise, as in Australia and Germany. However, for sites with peak demand costs in place, PV may be less attractive if peak demands mostly occur in the afternoon until late afternoon, for example housing communities. Overall, energy investment is largely an economical and better decision to make investment decisions based on systematic evaluation of options in operational improvement, energy efficiency, onsite generation and energy storage.

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See also

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References

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External links

• Solar Power/Photovoltaics
• Factsheet Energy Photovoltaics by the University of Michigan Sustainable Center System for
• House Power Magazine http://www.homepower.com/
• Solar project management
• Engineering Photovoltaics Systems
• Best Practices for the Determination of Solar Photovoltaics at Municipal Solid Waste Disposal: A Prepared Study in Partnership with the Environmental Protection Agency to Reactivate Land Initiatives in America: Propose Renewable Energy in Areas of Soil and Contaminated Mines Energy National Renewable Energy Laboratory

Source of the article : Wikipedia