Today we will introduce a home solar power system design below 10kW, which is installed on the roof of the house and connected to the grid of 220V or 380V. The maximum installation capacity is 25% of the capacity of the upper-level transformer. First of all, it is required to determine whether the load capacity of the roof can meet the requirements. The loading requirements of the solar power system equipment for the roof are greater than 30kg/m2.
With the constantly advance of industrial and commercial photovoltaics, there are less and less large-scale, flat, facing, unshielded cement or colored steel roofs, and the rest may be multi-angle, multi-oriented, sheltered, multi-structural roofs. How to design solar panel system on the complex roofs? The most concerned issue for designers and investors is to control the cost, ensure the power generation, and be safe and reliable.
The solar PV system is not only environmentally friendly, but also saves money and makes money, becoming a best choice of alternative or backup power source for many families. However, it need proper maintenance, so as to ensure the generating capacity of the system, and guarantee the service life. Do you want a better power generating efficiency and a longer service life of your home solar power system? It should be guaranteed by the sound maintenance.
The solar PV system is constituted by the solar cell, storage battery pack, charge controller, inverter, AC power distribution cabinet, lightning protection system, combiner box, DC power distribution cabinet, environmental monitoring system, monitoring system and other devices. The following is the overview of the main components of a solar PV system.
The light storage system includes solar energy components, controllers, solar inverters, batteries, loads and other equipment. At present, there are many technical routes, but the energy needs to be gathered on a certain point. At present, there are mainly two kinds of topological structures: DC coupling and AC coupling.
Leakage current of the photovoltaic system, which is also known as the square matrix residual current, is essentially a kind of common mode current. The cause is that there is parasitic capacitance between the photovoltaic system and the earth. When the parasitic capacitance-photovoltaic system-grid forms a loop, the common mode voltage will produce the common mode current on the parasitic capacitance. When the photovoltaic system is equipped with a industrial frequency transformer, because of the relatively high parasitic capacitance between the transformer windings in the loop, the common mode current generated by the common mode voltage in the loop can be suppressed to a certain extent. However, in a photovoltaic system with no transformer, the loop impedance is relatively low, and the common mode voltage will form a large common mode current, ie, leakage current, on the parasitic capacitance between the photovoltaic system and the earth.
Most of the PV inverters on the present market are generally in the IP65 protection level, with a certain degree of wind, dust and water resistance. However, in the summer, the ambient temperature is high, and various components in the inverter are prone to high temperatures during operation, resulting in a decrease in power generation efficiency and even affecting the service life of the components. Therefore, the inverter in some photovoltaic systems is installed with a sunshade to reduce the temperature of the equipment. In addition, the installation environment of the inverter should be well shaded and ventilated to ensure the convection of the air and also increase the power generation capacity of the power station
The energy flow path of the solar PV system usually contains a solar panel, a combiner box, a DC power distribution cabinet, a grid-tie inverter, an AC power distribution cabinet, and the connection cables. Based on the energy flow of the PV system, it is necessary to fully consider some important factors affecting the conversion efficiency in the design of the solar power system.
The installation scheme of common ground distributed projects is to install near a string of components at the closest. It adopts the fixed-rack installation or hoop-type installation to directly fix the equipment on the stand column. If this kind of scheme is used, it is required to pay attention to the strength of the rack and column, as well as the height of the solar PV inverter over ground, avoiding being submerged in stormy days because of being placed at a too low height.
The PV module capacity and solar inverter capacity ratio are commonly referred to as capacity ratio. Reasonable capacity ratio design needs to be considered comprehensively in the light of the specific project. The main influencing factors include irradiance, system loss, inverter efficiency, inverter life, inverter voltage range, assembly installation angle and so on. Because the inverter accounts for only about 5% of the system cost, the number or power of the inverter is reduced by the overmatching of the components in the distributed photovoltaic power station system, and the investment income is very small, which also bring other problems, the specific analysis is as follows.
Input overvoltage protection: When the DC-side input voltage is higher than the maximum allowable DC array access voltage of the grid tie inverter, the inverter is not allowed to start or stop within 0.1s (in operation) and a warning signal is released at the same time. After the DC-side voltage is restored to the allowable working range of the inverter, the inverter should be started and operated normally.
The micro-inverter technology directly combines the inverter with a single photovoltaic module to equip every photovoltaic module with an inverter module which is capable of DC-AC conversion and the MPP tracking. The inverter module can directly convert the power generated by the photovoltaic module into the AC for the AC load use or transmit it to the grid.
Charging controller, check the voltage setting of the rectifier and check the voltmeter to have normal indication. If the battery temperature is below 55°F (about 12.778°C), charging to a higher voltage (at least 14.8 volts for a 12 volt system) should be allowed. If your charge controller has the temperature compensation function, it will automatically adjust. If there is an external temperature sensor, please make sure that it has been attached to the battery. If there is no automatic adjustment function, it is required to manually increase the voltage and adjust back in the spring (adjust to 14.3 volts). If the charge controller is not adjustable, try to keep the battery in a warmer environment.
As one of the multiple development and utilization approaches of solar energy, solar photovoltaic power generation has the characteristics of pollution-free, renewable, flexible and storable and so on. The photovoltaic power generation system has been put into practical use in the fields of road lig...
The off-grid solar power system design is different from the grid-tie solar power system. The former needs to take into considerations many factors including the load, daily electricity quantity and local climate conditions and so on, to choose different design plans according to clients’ practical demands. Therefore, the off-grid solar photovoltaic system is comparatively complex. In order to ensure reliability of the off-grid PV system, a thorough survey of customer demands is very necessary. The design of an off-grid solar power system mainly composes of the inverter selection, solar panel capacity, and batteries capacity.
Now we take a design of off-grid solar power system for a small-scale fish farmer near a lake as case study. Due to long-distance power grid construction, not only the cost is high, but also the conductor power loss and voltage loss are huge. Meanwhile, the stability of power use cannot be ensured because of the typhoons, and the accidental power failure happens on a frequent basis, which can affect the power use for production and life. Therefore, the off-grid solar power system is adopted. The sunlight radiation intensity in the daytime is high, and the power generated by solar power system is directly provided to the solar inverter output to support the operation of electric devices. At the same time, the batteries are charged, and provides the power for the devices via the inverter at night.
In fact, there is a close connection between the photovoltaic power generation capacity and the grid voltage. The power generation capacity gap between regions with extremely unstable voltage and regions with stable voltage is around 10% to 20%. This paper mainly discusses the influence of the grid voltage on the system. The grid voltage can be divided into three conditions, namely low voltage, high voltage and dramatic voltage fluctuation. These three conditions will all influence the system’s power generation capacity.
To a solar energy grid-tie system, the time and climate will cause changes of solar radiation, thus resulting in constant changes of the power point voltage. In order to improve the generating capacity, and ensure that the solar panels can output the highest power, either when the sunshine is weak or when the sunshine is strong, the solar inverter usually introduces the boost circuit to expand the voltage of its working point.
The off-grid photovoltaic power generation system for household use consists of the photovoltaic module, supporter, controller, solar inverter, accumulator and power distribution system. The system's electric plan design should take the selection and computing of modules, inverters (controllers), and accumulators into consideration. Before the plan design, necessary preparation should be made, because the off-grid is customized without a unified plan. Therefore, the user load type and power, electricity consumption in the daytime and in the evening, and climate conditions of the installation place should be first learned. The power supply for the off-grid photovoltaic system relies on the weather, which is not 100% reliable.
The solar power system is used to convert the solar energy directly into the electric power via the solar cell module. The solar cell module is a solid device, which makes use of electronic characteristics of semiconductor materials to realize P-V conversion. In many areas without the power grid, the solar photovoltaic system can facilitate the lighting and domestic power supply for users. In some developed areas, it can be connected with the regional power grid to realize complementation. Then, how does the solar PV system work to generate the electricity used in our daily life?