We are making nature increasingly uninhabitable, and renewable energy sources are a great opportunity for us to correct this mistake, and among these sources, solar energy comes to the fore today. Photovoltaic systems are the most common method used to generate electricity from the sun. These systems consist of many components. Although almost everyone thinks of photovoltaic systems as consisting of solar panels, basic components such as batteries, inverters and charge controllers are also very important for this system.
What is Photovoltaic System?
photovoltaic ; literally means the production of electricity from photon. This production is provided by photovoltaic panels (PV). Today, it is the most common system used to generate electricity from the sun.
Photovoltaic systems are divided into 3 according to the use of the electricity produced. These are systems with storage, that is, off-grid systems , on-grid systems that operate submersible and centrifugal pumps, which are connected to the network and used for land irrigation. Before introducing these systems to you, I would like to introduce the basic system elements used in solar systems.
Photovoltaic (PV) System Basic Elements
Solar panels, which are the most basic part of photovoltaic systems, are the part where electricity is produced from the sun. The solar panel converts solar energy into electrical energy by means of solar cells made of semiconductor silicon material . Solar panels of different capacities are available. These vary according to the area and arrangement of solar cells. Widely used solar panels in the market; They are solar panels with a capacity of 5W, 10W, 60W, 100W, 150W, 260W and 275W. There are monocrystalline, polycrystalline, thinfilm and many more types of solar panels. I will cover these in a separate article.
Solar Panel for Photovoltaic Systems
The charge controller regulates and stabilizes the dc energy coming from the solar panel and creates a stable dc electrical energy for the charging of the batteries. In order to charge the batteries from a dc source, the charging current and voltage must be regulated and constant. The voltage and current produced by the solar panel are not constant, so a charge controller is needed for efficient charging of the batteries. Charge controllers also prevent reverse current flowing from the battery to the panels. It protects the battery from overcharging. The charge controller cuts off the electricity from the solar panel when the battery is full. There are two varieties. These; PWM and MPPT are charge controllers.
Battery quality is very important for off grid photovoltaic systems with solar storage . The battery should have a high charge-discharge efficiency and a long life. It should be resistant to temperature and adverse environmental conditions. We will cover the technical details of these in another article. Batteries commonly used in solar systems; gel batteries, special opzs type aqueous batteries and some deep cycle lead acid batteries.
Inverters are electronic devices that convert DC electrical energy into AC electrical energy. There are three types for Off-Grid photovoltaic systems : square wave, modified sine and full sine. Modified sine and full sine models are frequently used in solar systems. I will specify the details and technical specifications of all of them in a separate article.
If the inverters are full sine models, there are two types as MPPT and PWM . The new generation inverters used in solar systems are smart inverters that also contain a charge controller. This type of inverter shows the user the production information of the solar panel, battery voltage values, electricity usage. These inverters contain a convector (AC-DC converter) so that the batteries can be charged with the support of the mains or generator.
On-Grid that is connected to the network used in photovoltaic inverters are different. These inverters are specially produced for grid connections. It has features such as being able to work in coordination with the network, and providing electricity transfer from the network to the load as a result of power reduction in the panels. They are available in single-phase and three-phase variants. In these systems, the inverter power should be parallel to the panel power, unlike off-grid systems. On-Grid inverters have a remote monitoring feature. The user can remotely monitor parameters such as the production of the panels during the day, daily electricity consumption and total electricity generation. The user can follow the production and consumption wherever he is in the world.
Photovoltaic ( PV) Systems
Off-Grid Photovoltaic Systems (Storage Systems)
Off-grid photovoltaic systems are systems that are installed separately from the electricity grid, store the electricity produced by solar panels via batteries and convert it into electrical energy that we use at home with inverters. Off-Grid systems basically consist of 4 main parts. These; solar panel , battery pack, charge controller and inverters.
The system working principle is; The electrical energy produced from the solar panel is regulated by the charge controller and stored in the batteries. This stored energy is converted into electrical energy that we use at home with inverters. In a way, this is similar to the principle of charging the car battery of the alternator in vehicles. Battery quality is very important for off grid photovoltaic systems . Accumulators with high charge-discharge efficiency, resistant to high temperatures and long life should be preferred.
On-Grid Photovoltaic Systems (Grid Connected Systems)
These systems are actually a switchboard system, whether small or large. Because the electrical energy produced from the panels is sold to the grid using single-phase or three-phase inverters. Photovoltaic On-Grid systems ; It consists of 4 basic elements: solar panels, inverter, bidirectional counters and datalogger.
System working principle; The electrical energy produced from the solar panels is arranged by coming to the grid-connected inverters and converted into a form that can be transferred to the power line. The electricity produced from the solar panel is used directly to the load, and the excess is transferred to the grid. When the air is closed or the production is low, the electricity need is met by transferring electricity from the grid to the load. If there is a problem caused by the mains, the inverter turns itself off. In other words, if there is a power outage in the network, your home will also be cut off.
As can be seen, photovoltaic systems are a technology that includes many different disciplines. Therefore, while designing the systems, the capacity calculation and quality of these basic components should be determined very well.