并網(wǎng)系統(tǒng)和并離網(wǎng)系統(tǒng)的區(qū)別

光伏并網(wǎng)系統(tǒng)

特點(diǎn)：光伏并網(wǎng)系統(tǒng)，負(fù)載優(yōu)先使用太陽能，當(dāng)負(fù)載用不完后，多余的電送入電網(wǎng)，當(dāng)光伏電量不足時(shí)，電網(wǎng)和光伏可以同時(shí)給負(fù)載供電，光伏發(fā)電依賴于電網(wǎng)和陽光，當(dāng)電網(wǎng)斷電時(shí)，逆變器就會(huì)啟動(dòng)孤島保護(hù)功能，太陽能不能發(fā)電，負(fù)載也不能工作。

光伏并離網(wǎng)系統(tǒng)

光伏并離網(wǎng)系統(tǒng)由太陽能電池板、充電器、電池組、DSP控制器、逆變器等組成。通過充電器將PV直流輸入轉(zhuǎn)換為蓄電池和逆變器所需的電壓；電池組可采用鉛酸或鋰電池,用來儲(chǔ)存太陽能電池所發(fā)出的電能并可實(shí)時(shí)為負(fù)載或電網(wǎng)提供能量；DSP控制器用于MPPT跟蹤處理、BUCK變換器開關(guān)管控制及全橋逆變控制, 實(shí)現(xiàn)系統(tǒng)DC-DC前級(jí)降壓儲(chǔ)能及雙相逆變功能。

相對(duì)于并網(wǎng)發(fā)電系統(tǒng)，光伏并離網(wǎng)系統(tǒng)增加了充放電控制器和蓄電池，系統(tǒng)成本增加了一些，但是應(yīng)用范圍更廣。一是可以設(shè)定在電價(jià)峰值時(shí)以額定功率輸出，減少電費(fèi)開支;二是可以電價(jià)谷段充電，峰段放電，利用峰谷差價(jià)賺錢;三是當(dāng)電網(wǎng)停電時(shí)，光伏系統(tǒng)做為備用電源繼續(xù)工作，逆變器可以切換為離網(wǎng)工作模式，光伏和蓄電池可以通過逆變器給負(fù)載供電

The difference between grid-connected and hybrid systems  

Photovoltaic grid-connected system  

Features: photovoltaic (pv) grid system, load is preferred to use solar energy, when the load to burn, redundant into electricity grid, when the photovoltaic battery is low, power grids and photovoltaic power supply to the load at the same time, photovoltaic power generation depends on the power grid and the sun, when power grid, the inverter will start island protection function, solar can't power, load can't work.  

The picture  

Hybrid system  

Photovoltaic off-grid system consists of solar panel, charger, battery pack, DSP controller, inverter and so on.  The PV DC input is converted into the voltage required by the battery and inverter through the charger;  The battery pack can use lead-acid or lithium batteries to store the energy generated by the solar cells and provide real-time power to the load or grid.  DSP controller is used for MPPT tracking processing, BUCK converter switch control and full-bridge inverter control, realizing dC-DC step-down energy storage and dual-phase inverter functions.  

Compared with the grid-connected power generation system, the photovoltaic off-grid system increases the charge and discharge controller and battery, which increases the system cost, but has a wider application range.   First, it can be set at the peak of the electricity price to the rated power output, reduce the cost of electricity;   Second, the price of electricity valley charge, peak discharge, the use of peak valley difference to make money;  Third, when the power grid fails, the photovoltaic system continues to work as a backup power supply, and the inverter can switch to off-grid working mode. Photovoltaic and battery can supply power to the load through the inverter