How To Build Your Own Photovoltaic System?
1. Solar power generation system capacity design
Kapasiti is the power generation of the photovoltaic power generation system, which is generally designed based on the buildable area of the residents. An area of 1 square meter can currently generate about 300W of electricity. The average resident can build a 5kw-10kw power station, which requires approximately more than 25 square meters of installation space, and so on. The installation space can be a sloped roof or a flat bumbung.
2. Pemilihan of solar cell modules
Battery components are divided into monocrystalline silicon battery components, polycrystalline silicon battery components and amorphous battery components. Monocrystalline has the highest power generation efficiency and can generate more electricity in the same area. For small installation areas, monocrystalline is the most suitable choice, but the unit price will be higher. The efficiency of polycrystalline silicon is second. For those with a relatively large installation area, polycrystalline silicon is more cost-effective and the price is relatively low. Amorphous silicon has the lowest efficiency and is generally not recommended for use. (Tips: Monocrystalline cells generally have rounded corners, while polycrystalline cells generally have right angles)
The five major parameters of battery components are peak power, open circuit voltage, short circuit current, working voltage, and working current. The selection of these parameters is very important.
Battery components are divided into different sizes according to their power. The power of a single component ranges from 300W-700W. The power of a single component is directly proportional to the area, so when selecting the power, you should also choose the battery component of the most appropriate size to meet your installation space requirements.
Panel bawah sunlight (1000w/m2)
①The voltage measured without load is the open circuit voltage.
②The current measured by directly short-circuiting the positive and negative poles of the battery component is the short-circuit current.
③The voltage measured when a load is applied is the working voltage, and the current measured is the working current.
The operating voltage is generally proportional to the open circuit voltage, and the operating current is proportional to the short circuit current. The selection of these four parameters has a great relationship with the inverter to be selected later. Generally speaking, the open circuit voltage of grid-connected battery components is around 45 volts, and the operating voltage is around 35 volts. Operating current and open circuit current vary with component power.
Series and parallel connection of battery components: Multiple battery components can be used in series or parallel, or a mixture of series and parallel can be used. For grid-connected systems, series connection is to obtain a voltage suitable for the operation of the grid-connected inverter, and parallel connection is to increase the output power at the same voltage level.
3. Pemilihan daripada grid-connected solar inverter
As an interface device between photovoltaic cell components and the grid, the grid-connected solar inverter converts the DC power of the photovoltaic cells into AC power and transmits it to the grid. It plays a vital role in the photovoltaic grid-connected power generation system.
There are two types of household grid-connected inverters. One is a centralized grid-connected photovoltaic inverter with a minimum power of 1kw and an input voltage ranging from 150V-550V. The other is micro grid-connected photovoltaic inverter, which is generally used in the AC220V voltage level, with power ranging from 200W to 500W, and the input voltage is 12V ~ 28VDC. The usage of the two grid-connected inverters is very different. Centralized grid-connected inverters are generally larger in size and suitable for wall-mounted installation. Micro grid-connected photovoltaic inverters are compact and are generally installed nearby with battery modules (can be installed on a bracket below the battery module).
The main parameters of the grid-connected inverter are maximum input power, maximum input voltage, rated input voltage, starting voltage, MPPT voltage range, and output grid voltage.
1) The maximum input power is a limit value, and the peak power of the photovoltaic cell module should be about 90% of this value;
2) The maximum input voltage corresponds to the open circuit voltage of the battery module. The open circuit voltage of the module array connected in series must be smaller than this value;
3) The rated input voltage corresponds to the working voltage of the photovoltaic cell module and can have a certain range of deviation;
4) The starting voltage refers to the voltage point at which the grid-connected inverter starts to work. The grid-connected inverter will not work when the sunlight is too weak;
5) MPPT voltan range is a function of the grid-connected inverter set accord to the characteristics of the battery panel. It will automatically adjust the input voltage and current of the inverter so that the product of voltage and current, that is the power, reaches the maximum value. This The voltage range is very wide, and inverter panels with this function can be used more efficiently;
The output grid voltage refers to the voltage of the grid to be integrated, usually in China: single-phase 220V/three-phase 380V.
The choice of grid-connected inverter mainly depends on the rated power and input and output voltage levels. Then users can easily determine the input voltage range of the grid-connected inverter based on the voltage level and series-parallel connection method of the selected battery components. They can choose single-phase or three-phase according to the power consumption at home. output. Untuk contoh: the peak power of the battery panel is 200W, the open circuit voltage is 45V, and the working voltage is 35V. To form a 2KW system, 10 battery cells need to be connected in series, then the maximum input voltage of the grid-connected inverter must be greater than 45V/chip*10 Chip {= 450V, rated voltage is around 350V. The output voltage can be selected from single-phase 220V or three-phase 380V according to the specific power supply situation of the home. As the most important component of the entire system, the grid-connected inverter must choose products that have passed relevant certifications.
4. Pemilihan daripada lain komponen
1) Kabel. You can choose photovoltaic-specific cables, but they are expensive and difficult to purchase in small quantities. For short distances, BV cables are still used, and the safe current of 1 square millimeter is 6A. For example, for a system with a power of 3kw, for the photovoltaic input cable, the rated input voltage of the inverter is DC350V, then the current is 3000W/350V{{8% 7d} ≈ .57A, so choose a BV2.5 cable. For the inverter output cable, the rated output voltage of the inverter is AC220V, then the current is 3000W/220V ≈ 13.63A. In theory, you can juga choose a BV2.5 cable, but for safety reasons, it can be upgraded to a higher level. Select the BV4 cable.
2) Lightning protector. Lightning arresters are different from ordinary lightning arresters. You must choose a high-voltage DC lightning arrester dedicated to photovoltaics, because the continuous working voltage of ordinary lightning protectors is AC220V or AC380V, while the continuous operating voltage of photovoltaic-specific lightning protectors can be as high as DC1000V.
3) Mengukur instruments The electric power company will install two electricity meters for users free of charge. One is an electricity meter that measures photovoltaic power generation, and the other is a two-way meter, which is a meter that measures electricity used by the user himself and sold to the grid [2]. In this way, users can see their daily electricity consumption, power generation and power output to the grid dalam sebenar masa.
The above are the things you need to pay attention to when purchasing some related components for home solar systems. If you need more detailed information, please contact Jingsun.