Solar photovoltaic systems – AUTONOMOUS PHOTOVOLTAIC SYSTEMS

5.5.2 Autonomous photovoltaic systems

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION. The autonomous photovoltaic systems are designed to operate independently of the power grid and are generally designed and sized to supply certain DC and/or AC electrical loads. These types of systems may be powered by a PV array alone or use wind power, a motor generator, or utility power as an auxiliary power source in what is called a PV-hybrid system. The simplest type of stand-alone PV system is a direct connection system, where the DC output of a PV module or array is directly connected to a DC load ( Fig. 5.5). Since there are no electrical storage systems (batteries) in direct-connected systems, the load only operates during sunshine hours, making these designs suitable for common applications such as ventilation fans, water pumps and small circulation pumps for solar heating systems water heater. Matching the impedance of the electrical load to the maximum output power of the PV array is a critical part of designing a well-performing direct connection system. For some loads such as positive displacement water pumps. a type of electronic DC-DC converter, called a maximum power tracker (MPPT), is used between the panel and the load to make better use of the panel's available maximum output power.

AUTONOMOUS PHOTOVOLTAIC SYSTEMS FOR HOLIDAY HOME

 

Photovoltaic 2kwh with installation for small cottage or caravan- PHOTOVOLTAICS-AUTONOMOUS AUTONOMOUS

Figure 5.5 . Simpler type of autonomous photovoltaic system

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION: In many autonomous photovoltaic systems , batteries are used to store energy. Figure 5.6 shows a diagram of a typical autonomous photovoltaic system that supplies DC and AC loads. Figure 5.7 shows how a typical photovoltaic hybrid system can be configured.

Autonomous photovoltaic for cottage 4,5kWh for washing machine

Figure 5.6 . Diagram of an autonomous photovoltaic system with DC and AC charge battery power supply

Figure 5.7 . Diagram of the photovoltaic hybrid system

Conversion of photovoltaic system

3.6.2 Autonomous photovoltaic systems

STAND-ALONE PV SYSTEMS INFORMATION stand-alone photovoltaic systems are usually utility power inverters. They generally include solar charging units, photovoltaic storage batteries and controls or regulators as shown in figure 3.15. STAND-ALONE PV SYSTEMS INFORMATION installed on the ground or on the roof will require a mounting structure, and if AC power is desired, an inverter is also required. In many autonomous photovoltaic systems batteries are used for energy storage, as they can represent up to 40% of the total cost of the stand-alone PV system throughout its lifetime [ 33 ].

Figure 3.15 . Diagram of autonomous photovoltaic system with battery storage power DC and AC loads [8].

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION: These batteries cause losses in the PV system due to limited availability of time and energy to recharge the battery in addition to inadequate battery maintenance. Therefore, a charge controller is used to control the system and prevent overcharging and overcharging the battery. Overcharging reduces battery life and may cause gassing, while overcharging can lead to sulphurization and stratification, which results in reduced battery efficiency and lifetime [ 34–37 ].

Batteries are often used in stand-alone PV systems to store energy produced by the PV generator during the day and supply electrical loads as needed (during night or cloudy weather). Additionally, batteries in monitoring systems are required to operate at MPP in order to supply electrical loads with constant voltages. Almost, most of the batteries used in stand-alone PV systems are deep cycle lead-acid batteries [ 38 ]. These batteries have thicker lead plates that make them tolerate deep discharges. The thicker the lead plates, the longer the battery life. The heavier the battery for a given group size, the thicker the plates and the better the battery will tolerate deep discharges [ 39 ].

All deep-rolled batteries are rated at ampere-hour capacity (AH), the amount of usable energy that can be stored at rated voltage [40]. A good charge rate is about 10% of the total battery capacity per hour. This will reduce electrolyte losses and damage to the plates [38]. A photovoltaic system may need to be large enough to store enough energy in batteries to meet the demand for power during many days of cloudy weather, known as "autonomy days". The Institute of Electrical and Electronic Engineering (IEEE) (IEEE Std 1013-1990) [41], for the selection, charging and testing of autonomous photovoltaic systems (IEEE Std 1361-2003) [42]] and for their installation and maintenance ( IEEE Std 937-2007) [43].

Nickel-cadmium batteries are also used for stand-alone PV systems, but are often expensive and “may have voltage compatibility issues with some inverters and chargers” [ 44 ]. However, their main advantage is that they are not affected by temperature like other types of batteries, so they are mostly recommended for industrial or commercial applications in cold locations. IEEE has also developed some guidelines for installation and maintenance (IEEE Std 1145-1999) [ 45 ].

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION: To extend battery life and make the system work efficiently, a charge controller is required to regulate the flow of electricity from the PV modules to the battery and load. The controller keeps the battery fully charged without overcharging it. Many controllers have the ability to detect excess electricity drawn from the batteries to the load and stop the flow until sufficient charge is restored to the batteries. The latter can significantly extend battery life. However, controllers in a stand-alone PV system are more complex devices that depend on the state of charge of the battery, which in turn depends on many factors and is difficult to measure. The controller must be sized to handle the maximum current generated. Certain features should be considered before selecting a controller, such as adjustable set points such as high and low voltage cut-offs, temperature compensation, low voltage warning and reverse current protection. In addition, the controller should ensure that no current flows from the battery to the array at night.

Introduction of theory and practice in autonomous photovoltaic systems

In Practical Photovoltaic ManualSolar radiation is called the fuel of photovoltaics and its characteristics form the basis of system design, from the construction of arrays to the reliability of the supply of electricity from stand-alone photovoltaic systems. Understanding solar radiation is arguably the oldest part of physical science, but only recently has the statistical nature of solar energy been understood in detail. A number of sophisticated computer models are now available and are described in detail in Part I, which also summarizes therelevant aspects of solar radiation as an energy source and examines the main features and limitations of the available computer tools.

Conversion of photovoltaic system

24.7 Stand-Alone Photovoltaic System

The main advantage of photovoltaic systems is their flexibility to be applied in remote areas where network connection is either impossible or very expensive to perform. Such systems are called stand-alone photovoltaic systems and are described in this section.

Stand-alone photovoltaic systems are usually an alternative to electricity. They generally include solar charging units, storage batteries and controls or regulators as shown in Figure 24.17. Ground or ceiling mounted systems will require a mounting structure and, if AC power is desired, an inverter is also required. In many stand-alone PV systems, batteries are used for energy storage, as they can represent up to 40% of the total cost of the stand-alone PV system over its lifetime.

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION: Figure 24.17 . Diagram of autonomous photovoltaic system with DC battery charge and AC loads.

These batteries cause losses in the PV system due to limited availability of time and energy to recharge the battery in addition to inadequate battery maintenance. Therefore, a charge controller is used to control the system and prevent overcharging and overcharging the battery. Excessive charging shortens its life battery and can cause gassing, while overcharging can lead to sulfation and stratification, which results in reduced battery efficiency and battery life.

Batteries are often used in photovoltaic systems to store the energy produced by the photovoltaic generator during the day and supply electrical loads as needed (during the night or cloudy weather). Additionally, batteries in monitoring systems are required to operate at MPP in order to supply electrical loads with constant voltages. Almost, most batteries used in PV systems are deep-cycle lead-acid batteries. These batteries have thicker lead plates that make them tolerate deep discharges. The larger the lead plates, the longer the battery life. The heavier the battery for a given group size, the thicker the plates and the better the battery will tolerate deep discards.

All deep cycle batteries are rated at NAP capacity, the amount of usable energy that can be stored at rated voltage. A good charge rate is about 10% of the total battery capacity per hour. This will reduce electrolyte losses and damage to the plates. A photovoltaic system may need to be large enough to store enough energy in batteries to meet the demand for power during many days of cloudy weather, known as "autonomy days". The Institute of Electrical and Electronic Engineering (IEEE) (IEEE Std 1013-1990), for the selection, charging and testing of autonomous photovoltaic systems (IEEE Std 1361-2003) and for their installation and maintenance (IEEE Std 937-2007) .

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION: All deep cycle batteries are rated at NAP capacity, the amount of usable energy that can be stored at rated voltage. A good charge rate is about 10% of the total battery capacity per hour. This will reduce electrolyte losses and damage to the plates. A photovoltaic system may need to be large enough to store enough energy in batteries to meet the demand for power during many days of cloudy weather, known as "autonomy days". The Institute of Electrical and Electronic Engineering (IEEE) (IEEE Std 1013-1990), for the selection, charging and testing of autonomous photovoltaic systems (IEEE Std 1361-2003) and for their installation and maintenance (IEEE Std 937-2007) .

Nickel-cadmium batteries are also used for photovoltaic systems, but are often expensive. However, their main advantage is that they are not affected by temperature like other types of batteries, so they are mostly recommended for industrial or commercial applications in cold places. The IEEE has also developed some installation and maintenance instructions (IEEE Std 1145-1999).

To extend battery life and make the system work efficiently, a charge controller is required to regulate the flow of electricity from the PV modules to the battery and load. The controller keeps the battery fully charged without overcharging it. Many controllers have the ability to detect excess electricity drawn from the batteries to the load and stop the flow until sufficient charge is restored to the batteries. The latter can significantly extend battery life. However, the controllers in the stand-alone PV system are more complex devices that depend on the state of charge of the battery, which in turn depends on many factors and is difficult to measure. The controller must be sized to handle the maximum current generated. Certain features should be considered before selecting a controller, such as adjustable set points such as high and low voltage cut-offs, temperature compensation, low voltage warning and reverse current protection. In addition, the controller should ensure that no current flows from the battery to the array at night.

24.7.1 Power converters

There are different power converters for stand-alone systems and they have different modes of operation. They can be summarized as described below:

Power from the main voltage source

The power inverter can supply power directly to the load from the main voltage source, without using the battery. This function in some inverters is not taken into account and the load is simply supplied by the battery pack.

No power is available from the main voltage source

There may be no power due to the weather and then the battery will deliver energy to the load. This can be done through a direct connection or by examining a power converter.

Power provided by the main source and the battery pack

When the photovoltaic system can not provide all the required energy from the load, but there is still energy available, then the system could operate to require energy from both sources: the photovoltaic system and the battery pack. Not all power converters can work in this format.

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION: Charging the battery

Once the battery is empty, the charging function must be considered. The battery is powered by the photovoltaic system via a power converter. This function is displayed if there is energy available from the renewable source.

There is no energy available from any source

There may be no power due to the weather and also when the battery is discharged. then the system is off, until the system has the power to run.

For stand-alone applications, it is possible to test more than one solar panel in addition to the battery pack. Next, the multi-input power converter should be considered. One of the most important issues in these converters is power management, ie determining when each source should be used in order for the system to function optimally.

The role of solar radiation climatology in the design of photovoltaic systems

3.1 Introduction

Designers of PV systems must usually aim to extract the maximum economic return from any investment throughout the lifetime of the installation. One way to do this is to try to increase the incoming energy density by tilting the solar cell panels towards the Sun. However, the optimal slope for increasing daily energy density varies with the time of year. The value of the collected energy to the user also varies over time, particularly for stand-alone PV systems. For example, if electricity is to be used for lighting, the nighttime period when electric lighting is required will vary throughout the year. Thus, choosing the optimal slope and orientation of the collectors requires careful consideration. The design must also address the assessment of the effects of space obstruction on collection efficiency. Partial shading of photovoltaic panels is also undesirable. Thus a proper understanding of the geometry of solar motions is needed. Irradiance on inclined surfaces can only be calculated if the global irradiance can first be separated into beam and diffuse components on an hourly basis. The designer handles a three-dimensional energy input system. The ability to interrelate solar geometry and energy flows is usually important.

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION: The national meteorological services aim to provide generalized data for the areas they cover. Their work has two main elements:

short-range and long-range weather forecasts, and
providing climatic advice and data.

Climate information needs for insolation data have historically been met using ground-based observational records. More recently, satellite data has been increasingly used to generate terrain information. Satellite data are, for example, a critical component of the radiation database material available to users of SoDa-IS 2003. The ESRA 2000 solar radiation maps [1] are based on a combination of satellite and ground-observed data.

The design of photovoltaics depends on the successful exploitation of available climatic information in the detailed design work. The gap between the data that national meteorological services can provide and the system designers need is often quite wide. This section of the chapter reviews some of those available todaymethodologies to provide PV designers with quantitative information needed to tackle various design projects

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION: Performance must be assessed in the context of risk. Supply and demand must be matched with appropriate energy storage strategies. This gives particular value to the availability of time series of solar radiation data preferably linked to temperature data. The daily temperature range is closely related to the daily horizontal radiation received. The daily average temperature is usually dominated by the source of the air passing through the space. Polar air can bring low daily mean temperatures combined with large gains from solar radiation and are therefore associated with large diurnal temperature variations.

Base station installation and resource allocation in sustainable wireless networks

16.2.2 Device design

To alleviate the dynamic characteristic of green energy, photovoltaic (PV) energy system is studied to convert the fluctuating green energy into more stable and reliable electricity. The photovoltaic system consists of several components, including the photovoltaic modules, the battery, the charge controller and the inverter. It has been widely used in communication systems for many decades. To meet the different energy requirements of wireless devices, most PV system studies focus on building more reliable and stable power supplies to prevent power interruption and waste. The problem of sizing photovoltaic systems is one of the most critical issues and has been extensively studied in the literature. In [21] , a simple method for size was proposed of autonomous photovoltaic systems . In their work, load loss probability and load profile were used to represent the desired reliability and traffic demand, respectively. In [22] , three probabilistic methods were proposed to classify PV systems. The first method aims to design the backup and recharge battery to support a constant load within a certain period of time. The second method classified the battery with loss of charge probability with detailed computer simulation. The latter method used the Markov chain to model the state of charge of the battery. In [23], the paper analyzed various scaling tools for a stand-alone PV system and proposed a standardized simulation model for the PV scaling problem. Furthermore, they showed that the accuracy of the PV sizing problem depends on basic statistical laws, which have no obvious relation to the complexity of the models used.

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION: Based on the results of PV system studies, many recharge and discharge models have been proposed in wireless communication networks. The simplest way is to model the battery/energy buffer as charging and discharging processes and use a frame to represent the current state of the battery/energy buffer [19] . Some works [9,24] describe the capability of the PV system using energy harvesting at a fixed time or charging rate to simplify the complexity of the energy charging model. In [6] , the project aimed to create a realistic BSenergy consumption model with specific input parameters. The laboratory grouped BSs into macro-BSs and micro-BSs. For the macro-BS models, the current consumption model consists of only a static discharge power part. For micro-BSs, the discharge model consists of static and dynamic power consumption parts. Based on the existing solar-powered WiMAX and WiFi networks [25,26] , our experiments provided some reports of power models of solar-powered BSs.

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AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION,

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION,

AUTONOMOUS PHOTOVOLTAIC SYSTEMS INFORMATION. technical data for permanent residences houses, yachts, installation

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