Design and selection of photovoltaic off-grid system
Jul 06, 2022
This article hopes to let everyone know how to successfully build a photovoltaic off-grid power station through simple and plain language. 1. The value of off-grid systems From a long-term summary, the off-grid system is mainly based on the following starting points: (1) Places where there is no way to use mains electricity (grid), such as mountains, boats, cars, and the wild. This is the most typical off-grid system requirement; more than 80% of users want to achieve power supply through off-grid systems because it is inconvenient to use mains electricity. (2) Areas where there is mains electricity, but irregular power outages often occur. When there is a power outage, the photovoltaic off-grid system can continue to supply the load to meet the continuous power demand. (3) There is mains electricity, but it is hoped that the electricity bill can be reduced through the off-grid system. The off-grid system can not only charge the battery through photovoltaic modules, but also charge the battery by setting the utility power when the rate is low, and then supply the load by discharging the battery when the rate is high. 2. Typical off-grid system composition Off-grid system diagram The above figure is the composition diagram of a typical off-grid system. A few things to note: (1) Off-grid system means that the system output does not need to be connected to the mains grid like a grid-connected photovoltaic system. The output of an off-grid system is what supplies the load. (2) The off-grid system provides the V-F source, which is equivalent to the role of a power grid. (3) The main equipment in the off-grid system are: photovoltaic modules, off-grid inverters, battery packs, confluence devices, distribution boxes, and electrical loads. (4) The most streamlined off-grid system can only contain two parts: off-grid inverter and battery pack. /3, Off-grid system design process (1) It is a "tailor-made" process to confirm the demand for an off-grid system, because in most cases the loads that different users need to bring are the same, and the duration of electricity consumption is different. The correct way is to first confirm the requirements: what loads will be brought? How big is the load? How long do you use it in a day? Then figure out how big a system needs to be built. For example, a customer in North China needs to build an off-grid power station, the main load is a 3500W blower, the power consumption is 3 hours a day, and the backup power needs only 1 day. From this information, the power of the load is 3.5KW, and the power consumption per day is 10.5kWh. (2) Off-grid machine selection The early off-grid system control part is performed by MPPT controller + DC/AC converter. With the development of technology, mainstream manufacturers currently advocate the use of control and inverter integrated machines, and one device can be used at the same time. Implement functions such as Growatt's SPF ES series of off-grid inverters. After confirming...
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