In string solar inverter, there will be a number of solar panels connected to each other in series, usually a number 6-10 solar panel, and generating what we called string. This string positive and negative terminals “DC” will be connected to the string inverter input side. As the panels will be connected in series, the overall string DC voltage will be high (typically 200-850V) and the circulating current will be low (equal to one solar panel rated current).
Solar inverter is the brain of the solar system, although its basic role is to convert DC electricity comes from solar panels to usable AC electricity, now it takes the responsibility to monitor and control the whole solar system and provides important technical info required for solar system operation and maintenance crews to fix system errors, in addition to that it takes responsibility to manage batteries system incase of its presence in the solar system.
Solar inverter is the heart of the solar plant, it represents the main equipment that converts DC output from solar panels to AC electricity required to run all our appliances/machines/equipment. In addition, it takes the responsibility of monitoring and controlling the PV array system.
Usually at the beginning of the day, solar inverter AC output power is low, then it increases gradually with the increasing of the sun light reaching its max at noon time (2-3pm), then it reduces gradually and reaches its lowest value at the end of the day with the sun light absence. So, it’s like a bell curve.
The solar inverter in the practical application of optimization applications, you first need to make sure that people buy an inverter is relatively high quality. Only good quality products in order to be respected by the market and is recognized by consumers. We will introduce about how manufacturers realize quality control of the solar inverter.
For large solar array you can use multiple string inverters and connect all together with one AC output for your loads. By using grid tie string inverters such way, you can make use of different tilt and azimuth angles that can be applied even for each sting, so getting maximum yield. In addition, increasing the solar array reliability as for example the shadow in one string panel will not affect the efficiency of other strings.
Smart solar inverter
It’s the link to the smart grid. The solar inverter should have high advanced communication capability with smart grid in addition to analytic, computing and memory capabilities to provide all information and control features to the smart grid energy management system.
Off grid solar system is more complex in installation than on grid solar system, as it requires more components like charge controller and batteries, so it needs higher technical skills and costs more. Although of this, off grid solar system market grows and most of suppliers / manufacturers try to save the cost and complexity by searching and implements new techniques and services that you should pay attention for as following.
Many people working in solar industry knows about MPPT acronym, but few of them understand correctly, although it is an important feature that helps us increasing solar photovoltaic energy harvest. Simply put, it is DC to DC converter incorporated inside most of all modern solar photovoltaic inverters that enable maximizing DC energy harvest getting from solar panels at any time during the operation cycle.
Off grid solar inverter converts DC electricity comes from solar panels and stored in Batteries to AC electricity to be used to run all of AC loads types existing now like TV, refrigerator, oven, lights, air conditions…etc. What are parameters to check when buying the off-grid inverter?
Today we see many solar plants connected to the power grid, and there will be more and more in near future. All experienced power system engineers, and operators see that it is a must for these solar plants to have sophisticated control system to achieve coordination and integrity between them and other traditional power plants exist in the grid. This smart control system can be done only through solar inverters which represent the brain of the solar power plant.
Today, the new frontier of solar inverters become exist everywhere, it's the smart solar inverter which has the ability to interact with the power grid. It has internal advanced software that enable performing amazing actions. The smart solar inverter is able to connect with the grid even with the presence of disturbances like voltage changes, the inverter automatically switches from operating mode to standby mode, then operating mode or even turn off if the disturbances last for long time.
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.
