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Photovoltaic inverter: operation and types

Photovoltaic inverter: operation and types


Photovoltaic inverter, the "beating" heart of each photovoltaic system, but pulsane with direct current or alternating current? A dilemma given that thephotovoltaic inverter it is precisely that contraption that transforms the direct current produced by photovoltaic modules into the alternating current that is needed, also to be fed into the public grid.

Photovoltaic inverter: operation

The transformation from CC to AC is by no means the only thing that thephotovoltaic inverter, does much more and its reputation as the "heart of the plant" is fully deserved. While it "reverses" in fact, this device simultaneously controls and monitors the entire system by acting on various levels.

First, it guarantees that i photovoltaic modules always work at their maximum performance, depending on the irradiation and temperature, and it is no joke considering that photovoltaics depend a lot on the radiation it receives, and of constant, in nature, there is very little. Still in the area of ​​monitoring, thephotovoltaic inverter keeps an eye on the public network and ensures that the entire plant works in safe conditions.

Optimizing the power of the system is the task of thephotovoltaic inverter: the "fame" of everything, therefore, is in his hands, he must be able to "get out" from solar modules the greatest power in any situation. In case of anomalies in the power supply network to which it is connected it is always ours photovoltaic inverter who has the responsibility to realize it, first of all, and to intervene. It can immediately disconnect the system if the public network "goes crazy" or collapses, or contribute to support, temporarily and partially compensate for it. It depends on each plant.

It is always through the'Photovoltaic inverter that, through special communication interfaces, it is possible to control parameters, operating data and yields. With all these important tasks, it is necessary that this "heart" be protected. The temperature of the envelope that surrounds it must be checked: it also affects the degree of performance and if it is too high thephotovoltaic inverter risks being reduced in power.

In order not to run this risk, it is necessary to evaluate the place where the system is located, while also ensuring the presence of an efficient and reliable cooling device for the casing. While we're at it, the casing should also be resistant to bad weather, so is ours photovoltaic inverter it is really safe.

Photovoltaic inverter: types

To orient us among the countless types of photovoltaic inverter, let's classify them according to three important characteristics: the power, the dimensioning on the DC side and the topology. In a range of available powers ranging from 2 kilowatts to "different" megawatts, it is necessary to understand what is right for us. For residential installations installed on the roof, the typical values ​​are around 5 kW, if we switch to commercial systems the kW range from 10 to 20 as in the case of sheds or barn roofs. If we then talk about photovoltaic inverter for real power plants, the power must be greater than 500 kW, between 500 and 800.

For dimensioning on the DC side in a photovoltaic inverter the type of connection of the photovoltaic modules with it should be looked at: we can find a string, multi-string and middle. In the first case there is a series of photovoltaic modules connected in series, in the second there is a photovoltaic inverter with two or two or more string entries, ideal for photovoltaic generators composed of numerous partial or partially shaded surfaces. For large systems with a homogeneous generator, central devices with high power are recommended.

Regarding the topology, a photovoltaic inverter it can be single-phase, excellent for small systems, or three-phase, for larger systems, as an alternative to groups of more single-phase assembled. Another distinction is the presence of the transformer that allows the galvanic separation, necessary in some countries, and allows the grounding of the photovoltaic modules, necessary for some types of modules.

L'photovoltaic inverter without transformer it is preferable because it is smaller and lighter. Without a transformer, there is also a higher degree of efficiency: it is the most important parameter for evaluating the device and is represented by the percentage of energy "introduced" in the form of direct current that is re-emitted in the form of alternating current. A photovoltaic inverter modern achieves a 98% efficiency.

Photovoltaic inverter with storage

There is a way to solve one of the main problems of photovoltaics, namely the discontinuity of energy production. This way is to have a photovoltaic inverter with accumulation. Thus the device allows you to "retain" the energy produced by the photovoltaic system and not consumed immediately, and then be able to reuse it when the system does not produce it. For example, at night.

Thanks to'photovoltaic inveter with storage, photovoltaics can be proposed as a self-sufficient system from an energy point of view. The beauty is that even for existing systems there is a way to obtain this result, thanks to inverter with storage units designed to be perfectly integrated even when already installed.

In practice there is nothing magical, it is a trivially precious process: this photovoltaic inverter special accumulates in special batteries the energy produced but not consumed immediately. When the system does not produce electricity - evening and night hours - the accumulator feeds the previously accumulated electricity into the domestic network. It gets to cover on average 75% of a family's self-consumption.

Stand alone photovoltaic inverter

Stand alone photovoltaic systems, also called grid-off or stand-alone, are those that work independently from the grid. They too have thephotovoltaic inverter, it is usually on the market with a number of other devices in a kind of stand alone system kit.

Both thephotovoltaic inverter, and the other elements, are special because they have been designed to be installed quickly and easily. Usually the kit includes various ad hoc devices for stand alone as an interface and connections of various modules, data loggers for managing your system, intelligent current sensors and devices for connection and remote control of the inverter.

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