從上圖看出，采用高頻隔離技術(shù)的離網(wǎng)逆變器，峰值功率可以達到額定功率的兩倍；采用工頻隔離技術(shù)的離網(wǎng)逆變器，峰值功率可以達到額定功率的三倍。 那么，一臺3kW的高頻離網(wǎng)逆變器，可以帶動一臺1P的空調(diào)（啟動功率約5.5kVA），一臺12kW的工頻離網(wǎng)逆變器，可以帶動一臺6P的空調(diào)（啟動功率約33kVA）。逆變器給負載提供啟動能量，一部分來自于蓄電池或者光伏組件，超出的部分也是靠逆變器自己（內(nèi)部的儲能元件—電容和電感）來提供。

高頻 

SPF3000-5000TL HVM

工頻 

SPF 4000-12000T HVM

電容和電感都是一種儲能元件 ，不同的是電容是以電場的形式儲存電能，電容的容量越大，儲存的電量越多。 而電感則是以磁場的形式存儲能量，電感器磁芯的磁導率越大，電感量也越大，則能夠儲存的能量也越多。  

電容的原理 從其結(jié)構(gòu)便可以看出，如上圖，兩邊各有一塊金屬板引出兩個電極，中間由絕緣物質(zhì)隔開，在電容兩端未施加外部電場的情況下，兩個極板上所帶的正負電荷處于一種平衡狀態(tài)。 

如上圖，當在電容兩端施加外電場時，一端極板上開始聚集正電荷，另一端極板則聚集負電荷，隨著電容兩端的電壓不斷升高至電源電壓，電容充電停止，此時就算斷開外電路，電容上的能量也不會消失，原因是正負電荷具有“同性相斥，異性相吸”的特性，兩端的電荷相吸引就形成了儲存能量的作用。  

工頻隔離變壓器 ，是指頻率為工頻(50HZ)的變壓器，變壓器初級和次級都有電感，與逆變器里面的濾波電感，都可以儲存一定的電能。而當電感流過電流時，由于電流會存在磁場，當電流的磁場經(jīng)過磁芯時，電流磁場會打破“磁疇”的平衡狀態(tài)，使“磁疇”同時趨向于外部磁場的方向， 進而導致磁芯此時會對外表現(xiàn)出磁場。而這個磁芯磁場從無到有的過程，其實就是電感儲存磁場的過程。

電感 是由漆包線繞制在絕緣骨架或磁芯上形成的元器件。當線圈中有電流通過時，會在周圍產(chǎn)生一定的磁場，而當通過的電流含有交流成分時，產(chǎn)生的磁場會不斷變化，根據(jù)電磁感應原理，變化的磁力線又會在線圈兩端產(chǎn)生感應電動勢，但此電動勢的方向和原來產(chǎn)生的電動勢方向相反，并以此來阻礙電流的變化。  

由此可以看出，電感的主要作用是阻礙電流的變化。電流增加時，它會阻礙電流的增加，同時通過磁場儲存一部分能量； 而當電流減小時，它又會阻礙電路中電流的減小，并釋放出儲存的能量來維持電流。正因為電感有儲存能量的特性，所以才有濾波和延遲等功能。

總結(jié)

光伏離網(wǎng)系統(tǒng)，輸出功率是由負載決定。當有電動機等感性負載啟動時，短時間需要非常大的電流，而這些能量，光伏無法提供，蓄電池也不能提供，鋰電池短時間如果過載輸出，會引起爆炸。但是，逆變器里的電容、電感、變壓器可以儲能電量，還可短時間放大幾倍輸出而不會損壞。

As can be seen from the figure above, the peak power of the off-grid inverter using high-frequency isolation technology can reach twice the rated power; Off-grid inverter with power frequency isolation technology, the peak power can reach three times the rated power. Then, a 3kW high-frequency off-grid inverter can drive a 1P air conditioner (starting power about 5.5kVA), and a 12kW power-frequency off-grid inverter can drive a 6P air conditioner (starting power about 33kVA). The inverter provides starting energy for the load, partly from the battery or photovoltaic modules, and the excess is also provided by the inverter itself (internal energy storage components -- capacitors and inductors).

The picture

High frequency

SPF3000-5000TL HVM

The picture

Power frequency

SPF 4000-12000T HVM

Capacitors and inductors are both energy storage components. The difference is that capacitors store electric energy in the form of electric fields. The larger the capacity of capacitors, the more electricity they store. Inductors store energy in the form of magnetic fields. The larger the permeability of the inductor's magnetic core, the larger the inductance, and the more energy can be stored.

The picture

The principle of the capacitor can be seen from its structure. As shown in the figure above, there is a metal plate on each side leading to two electrodes separated by insulating material. In the case that no external electric field is applied to both ends of the capacitor, the positive and negative charges on the two plates are in a state of equilibrium.

The picture

As shown above, when both ends of an electric field applied in capacitance, end plate began to gather on the positive, the other end of the plate is gathered negative charge, as at the ends of the capacitor voltage rising to power supply voltage, capacitance charging to stop, if disconnect external circuit, capacitance on energy will not disappear, the reason is that with positive and negative charge on the characteristic of "the same, opposites attract", The charges at both ends attract and store energy.

Power frequency isolation transformer, refers to the frequency of power frequency (50HZ) transformer, transformer primary and secondary have inductance, and inverter inside the filter inductance, can store a certain amount of electric energy. When the inductor flows through the current, there will be a magnetic field. When the magnetic field of the current passes through the magnetic core, the current magnetic field will break the equilibrium state of the "magnetic domain" and make the "magnetic domain" tend to the direction of the external magnetic field, resulting in the magnetic field of the core at this time. The process of the core magnetic field from scratch is actually the process of inductive storage of magnetic field.

The picture

Inductance is a component formed by enameled wire wound on an insulating skeleton or magnetic core. When the coil is energized, can produce a magnetic field in the surrounding, when through the current communication ingredients, fields changing, according to the principle of electromagnetic induction, the change of magnetic field lines and can produce inductive electromotive force on both ends of the coil, but the direction of the electromotive force and the original electromotive force in the opposite direction, and to hinder the current changes.

The picture

It can be seen that the main function of inductance is to hinder the change of current. As the current increases, it blocks the increase and stores some of the energy through the magnetic field. When the current is reduced, it blocks the reduction of the current in the circuit and releases the stored energy to maintain the current. Because the inductor has the property of storing energy, it has the function of filtering and delay.

conclusion

The picture

Photovoltaic off-grid system, the output power is determined by the load. When a motor and other inductive load is started, a very large current is needed in a short time, and these energies cannot be provided by photovoltaic and battery. If the overload output of lithium battery is carried out in a short time, it will cause an explosion. However, the capacitor, inductor, transformer in the inverter can store power, but also a short time to magnify several times the output without damage.