逆变器并网和离网发挥的作用

离网光伏电站是把太阳能发电储存到蓄电池，然后通过逆变器转换成家用的220V电压。

并网光伏电站是指和市电连接在一起，并网光伏发电站没有电能储存装置，直接通过逆变器转换成国家电网需要的电压要求，并优先供家庭使用，家庭用不完的电可以卖给国家。

目前国家政策支持，正在大力扶持太阳能光伏发电，家庭光伏发电站只要发电，都会有国家补贴。不过并网的话要先跟当地国家电网部门申请。

并网，就是必须连接到公共电网，就是太阳能发电、家庭电网、公共电网联系在一起了，这是必须依赖现有电网才能运行的发电系统。

主要由太阳能电池板和逆变器组成，太阳能电池板发出直接经逆变器转换成220V交流电并给家用电器供电，当太阳能的发电量超过家用电器使用的电量时，多余的电就输送到了公共电网；而当太阳能的发电量不能满足家用电器使用时，就自动从电网中补充。而这整个过程都是智能控制的，不需要人工操作。

由于这种光伏发电系统不需要使用蓄电池，也就大大节省了成本，特别是国家的并网政策已经明确指明，家庭光伏电站可以免费入网，多余的电还可以卖给电力公司。

从投资的长远角度，按家庭光伏电站25年的使用寿命计算，6-10年左右可以回收成本，剩下的十几年就是赚到的。因此，如果想节省电费开支且电力供应方便的话，就选择并网太阳能发电系统，这也是目前主流的方式。

但是，并网也有其缺点，就是当公共电网断电时，光伏发电也不能运行。但是如果把其中的并网逆变器换成智能微网逆变器(并网与离网混合逆变器)，断电时电站仍可以正常运转。

那么，怎么才可以将白天发的电力储存起来晚上用？这需要添加控制器和蓄电池等，白天控制器将光伏所发的电力储存在蓄电池中，晚上控制器将蓄电池所储电力释放出来供照明使用。

离网光伏发电站也被叫做独立光伏发电站，是不依赖电网而独立运行的发电系统，主要太阳能电池板、储能蓄电池、充放电控制器、逆变器等部件组成。太阳能电池板发出的电直接流入蓄电池并储存起来，需要给电器供电时，蓄电池里的直流电流经逆变器并转换成220V的交流电。

这是一个重复循环的充放电过程。这种发电系统由于不受地域的限制，使用很广泛，只要有阳光照射的地方就可以安装使用，因此非常适合于偏远无电网地区、孤岛、渔船、户外养殖基地等，也可以为经常停电地区的应急发电设备。

这种系统由于必须配备蓄电池，且占据了发电系统30-50%的成本。而且蓄电池的使用寿命一般都在3-5年，过后又得更换，这更是增加了使用成本。而经济性来说，很难得到大范围推广使用，因此不适合用电方便的地方使用。

但对于无电网地区或经常停电地区家庭来说，又具有很强的实用性。特别是单纯为了解决停电时的照明问题，可以采用直流节能灯，非常实用。因此，离网发电系统是专门针对无电网地区或经常停电地区场所使用的。

Off-grid photovoltaic power stations store solar power to batteries, and then convert it into 220V voltage at home through inverters.

Grid-connected photovoltaic power station refers to the power station connected with the municipal power. Grid-connected photovoltaic power station has no power storage device, and directly converts to the voltage requirements of the national grid through the inverter. It is given priority to the household use, and the household can sell the electricity that is not used up to the state.

At present, the national policy support is vigorously supporting solar photovoltaic power generation. As long as the household photovoltaic power station generates electricity, there will be state subsidies. But if you want to connect to the grid, you need to apply to the local state grid department first.

The picture

Grid-connection means that it must be connected to the public grid, which means that solar power generation, home power grid and public power grid are all connected together. It is a power generation system that must rely on the existing grid to operate.

It is mainly composed of solar panels and inverters, which directly convert the solar panels into 220V alternating current through the inverters and supply power to household appliances. When the solar power generation exceeds the electricity used by household appliances, the excess electricity is sent to the public grid; And when solar power cannot produce enough electricity for household appliances, it is automatically replenished from the grid. The whole process is intelligently controlled and does not require manual operation.

Since the photovoltaic system does not require the use of batteries, it also saves a lot of costs, especially since the national grid-connection policy has clearly stated that the household photovoltaic power station can be connected to the grid for free, and the surplus electricity can be sold to the power company.

The picture

From the long-term perspective of investment, based on the 25-year service life of the household photovoltaic power station, the cost can be recovered in about 6-10 years, and the remaining ten years is earned. Therefore, if you want to save the cost of electricity and the power supply is convenient, choose the grid connected solar power system, which is also the current mainstream way.

However, grid-connection also has a drawback, which is that when the public grid is cut off, the photovoltaic generation cannot operate. However, if the grid-connected inverter is replaced by intelligent micro-grid inverter (grid-connected and off-grid hybrid inverter), the power station can still operate normally when the power is cut off.

The picture

So how do you store the electricity you generate during the day for use at night? This requires the addition of a controller and storage battery. During the day, the controller will store the electricity generated by the photovoltaic in the battery, and at night, the controller will release the electricity stored in the battery for lighting.

Off-grid photovoltaic power stations, also known as independent photovoltaic power stations, are power generation systems that do not rely on the power grid and operate independently. They are mainly composed of solar panels, storage batteries, charge and discharge controllers, inverters and other components. The electricity produced by the solar panels flows directly into the battery and is stored. When it is needed to power the electrical appliances, the direct current in the battery flows through the inverter and is converted into 220V alternating current.

The picture

This is a repeating cycle of charge and discharge. This kind of power generation system is widely used because it is not limited by the region and can be installed and used wherever the sun shines. Therefore, it is very suitable for remote areas without power grid, isolated islands, fishing boats, outdoor breeding bases, etc., and can also be used as emergency power generation equipment in areas with frequent power outages.

Such systems, because they must be equipped with batteries, account for 30-50% of the cost of the generation system. And the service life of the battery is generally in 3-5 years, after which it has to be replaced, which increases the cost of use. Economically speaking, it is difficult to be widely promoted and used, so it is not suitable for use in places where electricity is convenient.

The picture

However, it has strong practicability for households in areas without power grid or frequent power outage. Especially in order to solve the lighting problem when the power failure, you can use DC energy-saving lamps, very practical. Therefore, off-grid power generation system is specifically for the use of non-grid areas or frequent power outage areas.