When it comes to photovoltaic off-grid systems, photovoltaic off-grid systems are mainly composed of components, solar controllers/inverters, battery packs, loads, etc. Its practical application is very wide, widely used in transportation, military, aerospace and other fields, almost everywhere, the application of photovoltaic off-grid system is small to power bank, street lamp, to aerospace, transportation and so on. Taking our daily life as an example, the solar street light on the roadside is a small off-grid system that generates electricity through photovoltaics during the day, and the battery stores the electricity generated by the photovoltaic panels during the day, and uses the electricity stored by the battery to illuminate at night.
For the batteries in the off-grid system, there are several of them: the most important, the most expensive, and the most easily damaged. Off-grid systems are not connected to the grid, so batteries are needed to store electricity. Naturally, batteries are the most important part of the system. At present, batteries include lead-acid batteries and lithium batteries, which occupy 30%-50% of the cost of the power generation system in off-grid systems. Of course, the service life of batteries has always been criticized, which is also a major technical barrier in the current industry. From the perspective of batteries used in off-grid systems in the market, lead-acid batteries are generally around 3 years, and lithium batteries have a lifespan of 6 or 7 years. With the emergence of high-efficiency battery technology, the lifespan will become longer.
The photovoltaic grid-connected system is composed of components, grid-connected inverters, brackets and other related system accessories. Since the grid-connected system needs to be connected to the grid, it needs to be equipped with a two-way meter. The electricity generated by the grid-connected system is alternating current, which can be directly used in households. load, excess electricity can also be sold into the grid.
It is not difficult to find that whether it is an off-grid system or a grid-connected system, there are core components and inverters. But what is the difference between an off-grid inverter and a grid-tied inverter?
Mainly look at the following points: composition, cost, efficiency.
Looking at the structure first, grid-connected inverters generally have a two-level structure of boost and inverter, while off-grid inverters generally have a four-level structure, including controller, boost, inverter, and isolation.
Looking at the price, the cost of off-grid inverters is about twice that of grid-connected inverters. Off-grid system inverter its high cost. Mainly depends on the overload capacity is a hard indicator. The output of the off-grid inverter is connected to the load, and many loads are inductive loads. The starting power is 3-5 times the rated power, and the overload capacity is strong. This requires higher power and quality of components, and the natural cost is more expensive. . The photovoltaic grid-connected inverter is connected to the components at the front end, and the output at the back end is connected to the grid, which is different.
The third is efficiency. For the same power, the overload capacity of off-grid inverters is more than 30% higher than that of grid-connected inverters.