光伏发电催生储能行业爆发式增长

光伏储能系统是将光伏发电系统与储能电池系统相结合，主要在电网工作应用中起到“负荷调节、存储电量、配合新能源接入、弥补线损、功率补偿、提高电能质量、孤网运行、削峰填谷”等作用应用。通俗来说，可以将储能电站比喻为一个蓄水池，可以把用电低谷期富余的水储存起来，在用电高峰的时候再拿出来用，这样就减少了电能的浪费；此外储能电站还能减少线损，增加线路和设备使用寿命。

由于电网需要实时保持发电量和用电量的动态平衡，所以电网的调度就显得极为重要。但是光伏发电不同于传统能源，由于只能在白天发电，不能涵盖全天用电高峰，会出现用电量和发电量不平衡的现象。同时，由于光伏发电高峰受阳光影响，中午为高峰，早晚曲线变化大，即使是在白天时段，多云、降雨等天气情况都会产生影响光伏发电，不易为电网调控出力，为促进分布式光伏的规模化发展，分布式光伏配储能是最具潜力的能源模式之一。

1）并网式光伏储能系统

并网储能系统指的是并入电网的发电储能系统，发出的电力可能自用，多余的供应电网中其他用户。整个系统是包括光伏组件阵列、光伏控制器、电池组、电池管理系统（BMS）、逆变器以及相应的储能电站联合控制调度系统等在内的发电系统。

光伏组件阵列利用太阳能电池板的光伏效应将光能转换为电能，然后对锂电池组充电，通过逆变器将直流电转换为交流电对负载进行供电。智能控制器根据日照强度及负载的变化，不断对蓄电池组的工作状态进行切换和调节：一方面把调整后的电能直接送往直流或交流负载。

另一方面把多余的电能送往蓄电池组存储。发电量不能满足负载需要时，控制器把蓄电池的电能送往负载，保证了整个系统工作的连续性和稳定性。并网逆变系统由几台逆变器组成，把蓄电池中的直流电变成标准的380V市电接入用户侧低压电网或经升压变压器送入高压电网。锂电池组在系统中同时起到能量调节和平衡负载两大作用。它将光伏发电系统输出的电能转化为化学能储存起来，以备供电不足时使用。

1. Overview of photovoltaic + energy storage principle  

Photovoltaic energy storage system is a combination of photovoltaic power generation system and energy storage battery system, which mainly plays the role of "load regulation, storage of electricity, cooperation with new energy access, making up for line loss, power compensation, improving power quality, isolated network operation, peak cutting and valley filling" in power grid work and application.   Generally speaking, the energy storage power station can be compared to a reservoir, which can store the surplus water in the low period of electricity consumption and then use it in the peak period of electricity consumption, so as to reduce the waste of electric energy.  In addition, energy storage power stations can reduce line loss and increase the service life of lines and equipment.  

Because the power grid needs to maintain the dynamic balance of power generation and consumption in real time, the dispatching of the power grid is very important.   However, photovoltaic power generation is different from traditional energy sources, because it can only generate electricity during the day and cannot cover the peak electricity consumption throughout the day, there will be an imbalance between electricity consumption and electricity generation.  At the same time, due to the peak of photovoltaic power generation are influenced by the sun, the noon for peak and curve change is big in the morning and evening, even in the daytime, cloudy, rain and other weather conditions can affect the photovoltaic power generation, not easy for the grid control output, to promote the development of the scale of distributed photovoltaic (pv), with distributed photovoltaic energy storage is one of the most potential energy model.  

2. What are the benefits of photovoltaic + energy storage?  

1) grid-connected photovoltaic energy storage system  

Grid-connected energy storage system refers to the power generation energy storage system integrated into the power grid. The generated power may be used for its own use, and the excess power will be supplied to other users in the power grid.   The whole system is a power generation system including photovoltaic module array, photovoltaic controller, battery bank, battery management system (BMS), inverter and corresponding joint control and dispatch system of energy storage power station.  

The photovoltaic module array uses the photovoltaic effect of the solar panel to convert light energy into electric energy, and then charges the lithium battery pack. Through the inverter, the direct current is converted to alternating current to supply power to the load.   The intelligent controller continuously switches and adjusts the working state of the battery group according to the change of sunshine intensity and load: on the one hand, the adjusted electric energy is directly sent to the DC or AC load.  

On the other hand, the excess electric energy is sent to storage battery.  When the power generation cannot meet the load demand, the controller sends the power from the battery to the load, ensuring the continuity and stability of the whole system.  The grid-connected inverter system is composed of several inverters, which turn the DC in the battery into standard 380V mains and connect to the low-voltage grid on the user side or send to the high-voltage grid through the boost transformer.   Lithium battery pack plays two roles in energy regulation and load balancing simultaneously in the system.  It converts the electrical energy output by photovoltaic power generation system into chemical energy and stores it for use when the power supply is insufficient.