光伏儲能系統(tǒng)是將光伏發(fā)電系統(tǒng)與儲能電池系統(tǒng)相結(jié)合，主要在電網(wǎng)工作應用中起到“負荷調(diào)節(jié)、存儲電量、配合新能源接入、彌補線損、功率補償、提高電能質(zhì)量、孤網(wǎng)運行、削峰填谷”等作用應用。通俗來說，可以將儲能電站比喻為一個蓄水池，可以把用電低谷期富余的水儲存起來，在用電高峰的時候再拿出來用，這樣就減少了電能的浪費；此外儲能電站還能減少線損，增加線路和設備使用壽命。

由于電網(wǎng)需要實時保持發(fā)電量和用電量的動態(tài)平衡，所以電網(wǎng)的調(diào)度就顯得極為重要。但是光伏發(fā)電不同于傳統(tǒng)能源，由于只能在白天發(fā)電，不能涵蓋全天用電高峰，會出現(xiàn)用電量和發(fā)電量不平衡的現(xiàn)象。同時，由于光伏發(fā)電高峰受陽光影響，中午為高峰，早晚曲線變化大，即使是在白天時段，多云、降雨等天氣情況都會產(chǎn)生影響光伏發(fā)電，不易為電網(wǎng)調(diào)控出力，為促進分布式光伏的規(guī)?；l(fā)展，分布式光伏配儲能是最具潛力的能源模式之一。

1）并網(wǎng)式光伏儲能系統(tǒng)

并網(wǎng)儲能系統(tǒng)指的是并入電網(wǎng)的發(fā)電儲能系統(tǒng)，發(fā)出的電力可能自用，多余的供應電網(wǎng)中其他用戶。整個系統(tǒng)是包括光伏組件陣列、光伏控制器、電池組、電池管理系統(tǒng)（BMS）、逆變器以及相應的儲能電站聯(lián)合控制調(diào)度系統(tǒng)等在內(nèi)的發(fā)電系統(tǒng)。

光伏組件陣列利用太陽能電池板的光伏效應將光能轉(zhuǎn)換為電能，然后對鋰電池組充電，通過逆變器將直流電轉(zhuǎn)換為交流電對負載進行供電。智能控制器根據(jù)日照強度及負載的變化，不斷對蓄電池組的工作狀態(tài)進行切換和調(diào)節(jié)：一方面把調(diào)整后的電能直接送往直流或交流負載。

另一方面把多余的電能送往蓄電池組存儲。發(fā)電量不能滿足負載需要時，控制器把蓄電池的電能送往負載，保證了整個系統(tǒng)工作的連續(xù)性和穩(wěn)定性。并網(wǎng)逆變系統(tǒng)由幾臺逆變器組成，把蓄電池中的直流電變成標準的380V市電接入用戶側(cè)低壓電網(wǎng)或經(jīng)升壓變壓器送入高壓電網(wǎng)。鋰電池組在系統(tǒng)中同時起到能量調(diào)節(jié)和平衡負載兩大作用。它將光伏發(fā)電系統(tǒng)輸出的電能轉(zhuǎn)化為化學能儲存起來，以備供電不足時使用。

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.