Outside the Earth’s atmosphere, the intensity of solar radiation remains almost constant at 1370 W/m2, however, it ranges between 0 and 1100 W/m2. Even a small percentage of the energy entering the globe is many orders of magnitude more than humanity’s present energy use.
Particularly since the 1970s, research into solar energy has accelerated. The cost of installing solar energy systems has reduced as technology has advanced. Solar energy has established itself as an ecologically friendly energy source.
Solar energy is one of the most widely used renewable energy sources for producing electricity because of the availability of resources, low operational costs, and ecological mindset. It may be used in buildings, lands, enterprises, and factories.
Solar energy systems come in a variety of forms. These;
Grid-connected photovoltaic systems, often known as grid-tied or on-grid systems:
Grid-connected PV systems transmit the energy generated by solar panels to the grid. These systems are utilized in homes, offices, and manufacturing plants. Excess energy is sent back into the grid and can be used to calculate net energy usage. The most significant advantage of grid-connected solar energy systems is that they significantly reduce energy usage and even provide additional cash for the system owner with excess energy produced.
Off-Grid Photovoltaic Systems:
Off-grid PV systems are utilized in areas that require their energy supply. These areas either lack access to the grid or have unstable grid electricity. The system uses the energy generated by the solar panels that are stored in batteries to generate electricity. In farms, chalets, and isolated locations, off-grid systems are employed increasingly frequently.
Hybrid Photovoltaic Systems:
In hybrid photovoltaic systems, a storage option is also provided for grid-connected systems. The ability to produce constant energy production, reduce the requirement for the consumption point to connect to the grid, and provide energy demand even during extreme energy outages are the major advantages of having storage in these systems. In this approach, hybrid photovoltaic systems can offer uninterruptible energy and energy independence.
Tracking Systems:
Tracking systems may be used to steer photovoltaic panels to the optimal angle of sunlight. Solar panels are moved in accordance with the position of the sun using single- or dual-axis tracking systems, allowing for the utilization of sunlight at angles that are more effective. When compared to fixed-angle systems of the same capacity, this method produces significantly more energy.
Solar Energy Systems’ Fundamental Components
The components of a system to be built to generate electricity from solar energy vary depending on the application. There are panels, inverters, and auxiliary electrical circuits in general. When there is no sunlight (cloudy weather, winter season, rainy days, etc.), the battery group is incorporated into the system to ensure that energy is not lost. To protect the battery from overcharging and discharge, a battery charge controller can be employed. The design of a solar energy system is determined by the amount of energy required and the location.
Photovoltaic (Solar) Panels
Photovoltaic panels convert solar energy into electrical energy. Their effectiveness varies depending on the kind of panel, however, it ranges between 20 and 25%. Laboratory research is ongoing, to increase efficiency values. In Türkiye circumstances, sunlight lasts 6-8 hours in winter, 10-12 hours in summer. Sunlight hours in the Balkans average 5-7 hours in winter and 9-11 hours in summer.
If the climatic circumstances are favorable, panels can output their nominal power. The panel efficiency will drop if the panel glass is filthy, the angle of incidence of the sun’s rays is not steep, or the weather is excessively hot or cold. As a result, 10-30% greater panel power is chosen in system designs.
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Battery System
Batteries are the components necessary in solar energy systems to store energy once it has been collected from solar panels and to deliver energy when in use. Knowing the system’s energy use regime is the most essential component in estimating battery capacity. The energy utilized during periods when energy generation is not possible should not exceed the stored energy. This is one of the most essential considerations when selecting battery capacity. Solar energy systems employ a wide range of battery types. The most popular are as follows:
Lithium-Ion Batteries:
Lithium-ion batteries are becoming more popular in solar energy systems. They have a higher energy density, can charge and discharge quicker, and have a longer lifespan. Because of their great efficiency and minimal maintenance needs, lithium-ion batteries are favored in solar energy systems. The most popular variety in solar energy systems is lithium-ferrophosphate (LiFePO4).
Lead-Acid Batteries:
Traditionally, lead-acid batteries have been utilized for solar energy storage. Because of their low cost, they are desirable in various applications. However, lead acid batteries have limits in terms of energy density, longevity, and charge/discharge capacity when compared to lithium-ion batteries. When lead acid batteries are deeply discharged, they have a shorter lifespan and may require maintenance regularly.
Gel Batteries:
Gel batteries, which include a gel electrolyte, are a form of lead acid battery. These batteries are leak-proof and offer improved deep-discharge capabilities. They are favored over lead-acid batteries in solar energy systems.
Flooded Batteries:
The typical form of lead acid battery is a flooded battery. It is recommended because of its inexpensive cost, but keep in mind that fluid electrolyte levels must be monitored and maintained regularly.
Battery Charge Controller
It prevents the battery from being fully charged or completely discharged by adjusting the current coming from the solar panel. Depending on the current value required for the consumer, the type that can work compatible with the system must be selected. In addition, the battery charge controller must be compatible with the battery voltage. Direct current output can be obtained directly from the charge controller. Most regulators have a screen that shows numerical information about the charge status. Many regulator manufacturers have determined the regulator that should be selected according to the panel power and put it in their catalogs in tables.
Inverter
Inverters are converters of direct current to alternating current energy. In general, there are two sorts of inverters: those that produce a pure sine wave or modified sine wave. In systems with sensitive loads, inverters with pure sine output are required. The inverter power is calculated by adding the power values of all the loads that can function in the system at the same time.
Direct current (DC) power generated by solar panels is converted into usable electrical energy via solar inverters. When exposed to sunlight, solar panels generate direct current (DC) power, while houses and businesses frequently utilize alternating current power(AC).
Types of inverters:
Central Inverters: These inverters are frequently used to link several solar panels in arrays. A single inverter converts the entire system. They are most commonly seen in MW and larger-scale facilities.
String Inverter: Energy is converted by connecting strings made by merging many solar panels into smaller-power inverters. They are more compact versions of central inverters. There are devices ranging in power from 1kW to 250kW.
Micro Inverters: Micro inverters are devices that are created specifically for each solar panel. This enables each panel to be optimized and monitored separately. Micro inverters enable higher energy efficiency and panel-level monitoring. Because of their high cost, they are typically used in home installations.
Optimization Units: These systems monitor and optimize the performance of each panel without the necessity of a separate inverter to convert DC power to AC. They are frequently used in conjunction with string inverters. Optimizers attempt to reduce system losses by converting the variable voltage arriving from the panel to a constant value.
Solar inverters play an important role in boosting the efficiency of solar energy systems and transforming solar energy into useful power. The type of inverter will depend on the size of the installation, the cost, and the performance goals.
Other Equipment
Constructions, cables, and electrical protection devices (MCBs, surge protections, etc.) should also be included in the system. The system may also be monitored using a variety of electrical circuits. For the system to operate effectively, fuse and cable choices are crucial. When choosing cables, voltage drop should also be taken into account.