Protection elements of the photovoltaic installation
Like all electrical installations, photovoltaic solar panel systems must be equipped with the necessary automation to preserve the health of people and the integrity of the whole. are the different photovoltaic installation protection elements those in charge of carrying out this mission and their knowledge must be mandatory for the professional who is dedicated to its handling and construction.
Why should the protection elements of the photovoltaic installation be used?
Although electricity has become totally necessary nowadays, we must not forget that may carry certain risks capable of seriously harming people. Solar panel installations are not exempt from these risks, since we cannot forget that they are systems that convert energy from the sun into electricity and, for this, the use of protection automation is essential.
In this context, the current regulations indicate that in solar energy generating systems, as they are electrical circuits, they must have the photovoltaic installation protection elements necessary to preserve the health of people and the installation itself.
Of a general nature, it establishes certain classifications based on the risks of the installation. In summary, there are the following protection specifications:
- Those installations that have higher voltages above 48 V must have a grounding to which at least the structure for solar panels and the profiles in charge of supporting the generator.
- The photovoltaic installation protection elements They will be designed to protect people against all types of contact, both direct and indirect. In the event that there was a previous installation, its security conditions will not be altered.
- In addition, all installation must be protected against overloads, short circuits and overvoltages. The batteries, if any, must be specially protected by electromagnetic circuit breakers, fuses or any element capable of fulfilling this type of function.
Types of protections in photovoltaic installations
The different photovoltaic installation protection elements existing can be classified in three ways:
- Depending on the type of current: for continuous, those used to protect the solar panels and their wiring are used. Disconnectors, lightning protections are usually installed and if there are several strings in parallel, fuses are added., also ground connections in the supporting structure of the modules. For the alternating current part, the most used elements are circuit breakers, differentials and surge protection.
- Depending on the type of installation: they are subdivided into monophasic and triphasic. The protections are the same as the previous classification, the only thing that changes is the connection mode.
- Depending on the type of contactThey can be direct or indirect. The former protect people against the risks arising from contact with the parts of the installation that are live. They are usually defined in the UNE 20.460-4-41 standard. The second are those produced when elements that have been accidentally energized are touched. They are regulated by the ITC-BT-08 and by the UNE 20.572-1.
Most of the different protections are usually located to protect the line that connects the solar panels with the DC/AC inverter. These elements must be designed to protect against overvoltages, overloads and short circuits in the installation. Your configuration will depend on the size and type of each system and, in addition, you must take into account the following factors:
- The rated circulating current in the strings (photovoltaic solar panels connected in series).
- The total voltage generated in the photovoltaic installation.
In this way, the different protection elements of solar installations They must be selected according to their ability to withstand the maximum voltage of the system and they must be designed to open or close the circuits when the maximum voltage allowed is exceeded.
According to all this, we will have the different photovoltaic installation protection elements described below.
Types of protections in photovoltaic installations
The different photovoltaic installation protection elements existing can be classified in three ways:
- Depending on the type of current: for continuous, those used to protect the solar panels and their wiring are used. Disconnectors, lightning protections are usually installed and if there are several strings in parallel, fuses are added., also ground connections in the supporting structure of the modules. For the alternating current part, the most used elements are circuit breakers, differentials and surge protection.
- Depending on the type of installation: they are subdivided into monophasic and triphasic. The protections are the same as the previous classification, the only thing that changes is the connection mode.
- Depending on the type of contactThey can be direct or indirect. The former protect people against the risks arising from contact with the parts of the installation that are live. They are usually defined in the UNE 20.460-4-41 standard. The second are those produced when elements that have been accidentally energized are touched. They are regulated by the ITC-BT-08 and by the UNE 20.572-1.
Most of the different protections are usually located to protect the line that connects the solar panels with the DC/AC inverter. These elements must be designed to protect against overvoltages, overloads and short circuits in the installation. Your configuration will depend on the size and type of each system and, in addition, you must take into account the following factors:
- The rated circulating current in the strings (photovoltaic solar panels connected in series).
- The total voltage generated in the photovoltaic installation.
In this way, the different protection elements of solar installations They must be selected according to their ability to withstand the maximum voltage of the system and they must be designed to open or close the circuits when the maximum voltage allowed is exceeded.
According to all this, we will have the different photovoltaic installation protection elements described below.
Circuit breakers
This elements offer protection against short circuits and overcurrents quite reliably. Its design is designed to withstand DC voltages of 1000 V. This value is imposed by the number of existing panels, so that if each of them supports 250 V, a 4-module switch will be designed to withstand a maximum voltage of 1000V
fuses
Like the previous ones, the fuses protect against overcurrents that may occur. They must be chosen according to the type of current and the system voltage. In installations where there are no stings in parallel, it is not necessary to install fuses, since a current greater than its short-circuit current can never reach the solar panel.
Break disconnectors
Disconnectors that close the circuit when overcurrents occur.
The disconnectors allow us to open the DC circuit when we need it, for safe handling. It is very important that they are specific for DC and they do not need to be automatic, since the panel will never receive an intensity greater than its short-circuit current. In this way, a high degree of reliability and safety is produced in the installation. These additional elements will have to be designed according to the current and the installation of the system.
surge arrester
Dischargers are elements that earth overvoltages derived from atmospheric phenomenasuch as lightning strikes. They are devices in charge of protecting both the solar panels and the inverter, and their use is highly recommended, since they prevent them from breaking down.
They are connected in parallel to the electrical installation to guarantee that the discharges are derived to ground. They will be selected taking into account the maximum voltage foreseen in the system is less than the working voltage of the arrester. These must be placed both in AC and DC and one for each polarity and string.
The photovoltaic installation protection elements They are necessary to provide people with the necessary safety from the risks arising from exposure to electricity. They are mandatory according to current regulations and must be designed according to the specific characteristics of the system.
