Off-grid photovoltaic power generation systems are suitable for areas where there is no grid connection or grid-connected power instability. Off-grid PV systems usually consist of solar modules, controllers, inverters, battery packs and bracket systems. They generate DC power directly through the day or in the battery pack for powering at night or on cloudy or rainy days. Off-grid PV systems are a stand-alone solution as they can be installed in most locations and are easy to maintain locally. They are an effective, clean and cost effective solution to replace diesel generators. JDSOLAR is born with the mission of "making people clean energy"! The photovoltaic off-grid system developed by JDSOLAR has a wide range of applications, not only to solve ordinary lighting power, but also to household appliances such as air conditioner refrigerator washing machines, etc. It can also solve the demand for field electricity, such as solar pump water supply system.
Conventional off-grid photovoltaic power generation systems include microgrid systems, residential off-grid systems, off-grid communication base station systems, solar street lighting systems, and building integration systems. It can be built in rural areas, pastoral areas, mountainous areas, developing large, medium and small cities or commercial areas to solve the needs of local users.
The JDSOLAR microgrid system is an independent control unit that integrates various types of power generation equipment, energy storage, load and control equipment to generate electricity or heat to the user. It can meet the diverse needs of users, the system capacity from tens of kilowatts to hundreds of kilowatts or even megawatts.
The JDSOLAR residential off-grid system can be installed on the roof or on the ground. According to the IEA survey, 1.456 billion people live in a power-poor environment, 83% of whom live in rural areas, which is why most off-grid systems are used in rural areas. It has the characteristics of low cost, clean, reliable, convenient and easy to install and maintain. The one-time investment can be exchanged for more than 25 years.
The off-grid solar communication base station BTS can be installed lightly without taking up too much land resources and can generate electricity immediately. The off-grid communication base station system has reliable power resources, sufficient energy storage for emergency needs, clean and renewable, easy maintenance, and low-cost investment to obtain 25 years of power supply.
The JDSOLAR Solar Street Light System uses efficient components to provide a source of electricity. During the day, the components charge the battery; at night, the battery provides enough power for the bulb. It has a variety of control modes, such as time control, light control, remote control, etc. You don't need to manipulate it yourself, nor do you need complicated and expensive wire laying. In addition, this solar street light uses a low-voltage DC power supply, which makes it safer and more reliable, and it can be widely used in criss-cross streets, country roads, and so on.
In addition to the function of green power generation, the building integrated photovoltaic system has the advantages of beautiful and moderate light transmission, and is widely used. Green building projects combined with architecture are increasingly becoming a highlight of urban architecture. The transparent solar modules developed by JDSOLAR are used in high-end art buildings, scenic sightseeing corridors, and photovoltaic glass curtain walls, making urban architecture a fusion of technology, architecture and art.
The photovoltaic off-grid power generation system developed by JDSWOLAR first meets the user load usage, and then stores the excess power in the battery for night and rainy days. When the battery is dead, most inverters can also support the mains input ( Or a diesel generator) as a supplemental energy source to power the load.
JDSOLAR photovoltaic off-grid system needs to consider the user's load size, daily electricity consumption, local climatic conditions and other factors, according to the actual needs of customers to choose different design options, the design of photovoltaic off-grid system, need to understand the customer's information mainly includes The following aspects:
1. Where is the solar power system used? What is the radiation situation in the area?
2. What is the load power of the system?
3. What is the output voltage of the system, DC or AC?
4. How many hours does the system need to work every day?
5. How many days does the system need to be powered continuously in the event of rainy weather without sunlight?
6, the load situation, pure resistance, capacitive or inductive, how much starting current?
Selection of main components
Inverter selection: determine inverter power based on user load size and type
The off-grid inverter is one of the core components of the off-grid solar power system, which is responsible for converting direct current to alternating current for AC load. In order to improve the overall performance of the photovoltaic power generation system and ensure the long-term stable operation of the power station, the performance index of the inverter is very important. Inverter selection is based on the characteristics of the load (such as resistive, inductive or capacitive) and load power.
The choice of inverter power size is generally not less than the total load power, but considering the service life of the inverter and subsequent expansion, it is recommended to consider the inverter power to leave a certain margin, generally 1.2~1.5 of the load power. In addition, if the load contains an inductive load with a motor similar to a refrigerator, an air conditioner, a water pump, a range hood, etc. (the starting power of the motor is 3 to 5 times the rated power), it is necessary to take into account the starting power of the load, that is, The starting power of the load is less than the maximum impact power of the inverter. The following is the calculation formula for the power selection of the inverter, which is used for design reference.
two. PV module capacity determination: component capacity is determined based on user daily electricity consumption and light intensity
Part of the electricity generated by the PV modules during the day is supplied to the load, and the rest is used to charge the battery. At night or when the solar radiation is insufficient, the electricity stored in the battery will be discharged to the load. It can be seen that there is no mains or diesel engine. In the case of supplementary energy, all the electricity consumed by the load comes from the electricity generated by the photovoltaic modules during the day. Considering different seasons, the light intensity of different regions will be different. In order to ensure the reliable operation of the system, the capacity design of the photovoltaic panels should be the most in the light. The poor season can also meet the demand. The following is the capacity calculation formula for PV modules:
Third, the battery capacity is determined: according to the night electricity consumption or backup time to determine the battery capacity
The main task of the battery pack is to store energy to ensure that the load is used at night or on a rainy day. The number of series and parallel connections of the battery can be configured according to the requirements of the DC voltage level of the system. When the batteries are connected in series and parallel, the same model specifications, the same manufacturer, the same batch, and the principle of simultaneous installation and use should be followed.
For photovoltaic off-grid systems with significant loads, battery capacity design requires consideration of the longest rainy days in the area. Ordinary photovoltaic off-grid system load power requirements are not high, considering the system cost reasons, you can not consider the number of rainy days, as long as the actual use of light intensity to adjust the use of the load. In addition, most of the photovoltaic off-grid systems use lead-acid batteries, and the lead-acid batteries generally have a discharge depth of 0.5-0.7.
Fourth, solar charge and discharge controller
The solar charge and discharge controller is also called "photovoltaic controller". Its function is to regulate and control the power generated by the solar cell module, to maximize the charging of the battery, and to protect the battery from over-charge protection and over-discharge protection. effect. In places with large temperature differences, PV controllers should have temperature compensation. According to the DC voltage level of the system and the power of the solar cell module, a suitable photovoltaic controller is available. The common photovoltaic controllers have different voltage levels of DC12V, 24V, 48V, 110V, and 220V.
Fives. JDSOLAR10KvA photovoltaic off-grid system design
Project Background: Design a photovoltaic off-grid system for a school in Africa to meet its daily electricity use.
1) Project demand survey
In the early stage of the design plan, the project needs survey needs to be done (the load information must be accurate), as follows:
2) Inverter selection
The customer's load is mainly classroom lighting, classroom fans, public places lighting, wall lighting and broadcasting systems, etc. The total load power is 6.84kw, the inverter power selection is not less than 9.8kVA, and the JDSOLAR reverse control integrated machine can be selected.
The power is 10kVA.
3) Determination of PV module capacity
According to the customer demand questionnaire, the average daily electricity consumption of the school is about 61.5kWh, and the local lighting conditions are good. According to the daily sunshine time of 4.23h, the component configuration is 1.1 times margin, and the design uses 88 270W polycrystalline photovoltaic. The total power of the module is 23.76kW, and the average power generation is 100.5kwh per day. Considering the system efficiency, it is generally 0.8, and the available electricity is 80kwh per day.
4) Battery capacity determination
Most of the school's lighting is used at night. Considering the battery life, the battery capacity should be increased appropriately. The battery backup time required by the customer is 2 days, and the battery discharge depth is 0.7. The project uses 110 AAA/2V. The colloidal battery is connected in series, the total capacity is 220,000VAH, and the available electricity is about 154kwh, which can meet the power demand of 2 days of backup time.
5) System plan