The Solar panel inverters are an essential component in the operation of solar photovoltaic systems, without these devices would be impossible to use the energy produced by the solar panels at home.
Solar panel inverters
Before talking about solar panel inverters and how they are part of a photovoltaic system we are going to mention the components of the solar system
Components for a photovoltaic installation.
The main components for a photovoltaic installation for a house serve to meet the needs of own consumption of electricity. These are the components for a photovoltaic installation:
• Panels or solar modules . What are they for? They are the elements that we need to capture solar radiation and transform it into electricity generating direct current. How many panels will you need for an installation? The number of solar panels will depend on the power that needs to be supplied. Its arrangement and form of connection (in series or in parallel), will be a function of the nominal supply voltage and the current intensity that you want to generate.
• Regulator or charge controller . It serves to control the charge of the batteries from the modules or generators panels, as well as their discharge to the interior power supply circuit of the house, also avoiding excessive charges or discharges of the battery set.
• Accumulators or batteries . They serve for the storage of energy. This energy is produced during the day with solar radiation and is used at night, in prolonged periods of bad weather or with little solar radiation. In addition, the use of batteries allows to inject a higher intensity of current than the solar panels themselves can deliver, if the interior installation of the house requires it.
• Inverter or DC / AC converter , a device that allows the conversion of the direct current (DC) generated in the photovoltaic panels into alternating current (AC) so that it can be used by the receivers and household appliances used in the home.
What is a solar inverter?
The solar inverter converts the energy collected by the solar panels (direct current) into electricity that you and I can use (alternating current). There are 3 types of technology and we will help you so you can choose which is the best for your solar installation.
To convert the direct current (DC) from the photovoltaic generators into alternating current (AC) for its consumption in the house we need a DC / AC current converter device called an inverter.
To guarantee the quality of the energy discharged in the electrical installation of the house, it is necessary to synchronize the frequency of the injected current with that of the network, adapting it to the required conditions according to the type of load and this synchronization is carried out by the inverter.
When we talk about installations with solar panels , the panels themselves are not the only element to be taken into account. Equally important are other components, such as the solar inverter, as it is responsible for converting the solar energy collected by the solar panels into electricity that you and I can use to turn on the lights or use our appliances.
What is the main characteristic of an investor?
The inverters are mainly characterized by the input voltage from the batteries, the maximum power it can provide and its efficiency or power output.
The latter is defined as the relationship between the electric power that the inverter delivers for its use (power output) and the electrical power it extracts from the battery system or from the photovoltaic generators (input power).
What requirements must investors comply with in photovoltaic installations?
• The efficiency should be as high as possible to minimize losses.
• The inverters must be protected against short circuits and overloads.
• The inverters must contain elements that include the automatic reset and disconnection of the inverter.
• Inverters to cope with the starting peaks produced by many appliances must be able to accept instantaneous power demands greater than 150% of their maximum or rated power.
• Investors must offer low harmonic distortion and low self-consumption.
• The inverters must have galvanic isolation.
• Investors must have a measurement and monitoring system.
• The inverters will incorporate manual controls that allow the general switching on and off of the inverter, and its connection and disconnection to the AC interface of the installation.
The protections that the current inverters must incorporate in their functions are:
• Protection against overloads and short circuits, which will allow detecting possible failures produced in the input or output terminals of the inverter.
• Protection against excessive heating, which will allow to disconnect the inverter if the temperature of the inverter exceeds a certain threshold value, and stay disconnected until the equipment does not reach a pre-set lower temperature.
• Island mode operation protection, which will disconnect the inverter if the voltage and frequency of the network are outside the threshold values that allow correct operation.
• Isolation protection, which detects possible insulation faults in the inverter.
• Protection against polarity reversal, which allows the inverter to be protected against possible polarity changes from the photovoltaic panels.
• Finally, the enclosure or housing that protects the inverter device will offer a class 1 basic insulation degree and a minimum degree of protection IP20 for those inverters installed inside buildings and are inaccessible places of IP30 for inverters located in the interior of accessible buildings and places, and with a minimum degree of protection of IP 65 for inverters installed in the open.
Selection of inverter voltage. Inverter to 12, 24 or 48 V
Another issue to take into account is the battery system we have, if it is 12, 24 or 48V, since the inverters only operate at a single input voltage. In addition, the more power we need available, the recommendation is that the battery system work at higher voltage, so that less consumption amps are needed and the losses in the cables and the system as a whole are lower.
Although there are increasingly more powerful inverters for all available voltages, as a general rule in 12V inverters of up to 2,000-3,000W are recommended, for 24V up to 5,000-6,000W and for 48V you can find all kinds of solutions up to very high powers.
How does a solar inverter work?
The solar panels are made up of different photovoltaic cells that, when receiving solar energy, react by moving the electrons. That reaction produces electricity from direct current, which is picked up by the circuits that are inside those solar cells.
It is at this point where the solar inverter operates, since the vast majority of houses use alternating current, so that the direct current produced by the solar panels will not serve to illuminate our home.
Therefore, the energy collected by the solar panels in the form of direct current is converted into alternating current electricity when it passes through the inverter , which is responsible for carrying out this «transformation». And at that moment, we can use that energy, pour it into the grid or store it in batteries , if we have them
What types of investor are there?
All solar inverters on the market convert direct current into alternating current, however, we can distinguish different technologies that, in addition to that, have other functions:
Inverter String (chain)
This is without a doubt the standard investor. It is known as the centralized or «chain» inverter, where each solar panel is connected in series and the energy is sent to a single inverter.
In favor : they are the cheapest and most standardized option , so it has a simple maintenance and are easy to find and recognize.
Take into account : having a single inverter placed in a chain, which does not distinguish between the different plates, it will produce as much useful electricity as the solar panel that produces less; Not recommended if you have different hours of shade per day. However, it is perfect for homes with roofs that receive sun throughout the day.
Unlike the previous one, the microinverter is considered the «distributed» inverter because one is placed on each solar panel.
In favor : they are more efficient than String because they produce energy even if one of the panels does not work.
Keep in mind : they are more expensive than String, and since they are installed on the deck, they can be more difficult to repair. Of course, if your solar installation is on a cover «with obstacles» (chimneys, complicated shapes …), has solar panels with different orientations, or simply want to maximize your production, microinverters are the best option for you.
The power optimizer is a complement to the classic String inverter; a middle term between the classic and the microinverter. Like a microinverter, the optimizer is installed on the roof individually in each solar panel, with the difference that it sends energy to a centralized inverter (String).
In favor : an installation with a power optimizer will always be more efficient than just with a chain inverter, in addition to being cheaper than microinverters . They allow to control each solar panel.
Keep in mind : Adding an optimizer makes the cost of your chain installation more expensive, so they are the option for those who want to increase the efficiency of their installation but not acquire microinverters. They can be added later.
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