PV system using power distribution mode, in order to make the rated power of the normal operation of the load, and the battery in the photovoltaic power distribution system is the role of multiple. For photovoltaic matrices and grid charges, the battery can be regarded as a load cell, and for the load, the battery is the power supply. The battery balances the power in the photovoltaic system and stores the energy. In addition, the battery in limiting the maximum power output of the photovoltaic matrix is also very important to play the effectiveness.
Photovoltaic system used in the battery mostly lead-acid batteries. The traditional technical indicators of such batteries are mainly used to adapt to the application in the electricity system developed. As a common emergency power supply, the key requirements are storage capacity, maintenance performance and float life. As a motor vehicle, a large current discharge and a number of cycles are required. In the photovoltaic power generation system in the application of the battery, in addition to considering the service life and power generation, maintenance and other properties, but also because of the expensive photovoltaic power, the battery performance requirements of efficient charge and discharge. In efficient photovoltaic systems, the efficiency of the battery determines the efficiency of the system. However, almost all of the battery suppliers do not provide product efficiency characteristics.
The efficiency of the battery is not only different characteristics of the battery with a unique fixed parameters, but also a battery in different conditions of use under the dynamic performance of the old and new batteries are not the same efficiency. Different battery efficiency, although the difference is very large, but the same battery in the float and high current discharge can also make the battery in a low state. Therefore, the product does not provide product efficiency performance of the battery products, there is no way to know it in the PV system in the working state, do not understand the important features of this important component, it is impossible to design a reasonable photovoltaic system. The reason why people engaged in photovoltaic systems engineering research people do everything possible to avoid the use of batteries, because they do not understand the battery will give the system what impact. Facts have also proved that their worries are justified, but the use of the battery system, whether it is grid-connected inverter system or the independent system of street lights, the problems, are all caused by the battery. Moreover, obviously the floating life of up to 20 years of battery, in the PV system in a year to scrapped the situation has been common.
Is not written on the packaging of solar energy dedicated battery will be suitable for applications in the photovoltaic system. Good quality of the battery only in the understanding of its characteristics, according to local conditions of the design, rational use, in order to meet the design requirements. Due to the different battery performance, the PV system can not give a unified design method. However, the PV system is stressful to the system, efficient and battery life is also positively related. Battery in the photovoltaic system operating conditions and different in the network, the manufacturers provided by the battery parameters can only be used for reference.
To design an efficient photovoltaic system, first of all to the system used in the characteristics of the battery to do targeted testing and testing to determine the photovoltaic system power distribution program. Sometimes this type of test will put many famous brands of batteries denied. Some of the batteries that are in good use in conventional power systems are almost completely incompatible with the technical specifications used in photovoltaic systems. Even if the selection of some products are basically applicable, but also have to discuss with the manufacturer to further improve the efficiency of the measures. Technical improvements related to the cost increase, which is not only to greatly increase the system cost, it is not the general PV system design and construction units have the ability to complete the work.
To some extent, the success or failure of the design and construction of photovoltaic systems lies in the rational use of batteries. If even the photovoltaic system performance requirements of the battery do not understand, rush to install the photovoltaic system, it will fail. The system designed according to the performance of a particular battery is an organic whole and can not be changed. There are two identical systems installed almost simultaneously, one installed in the Hefei National University Science and Technology Park, during which never changed, so far normal operation; another installed in the Anhui Provincial Exploration and Design Institute, after being replaced by the battery, but also changed the control Device, after the failure of the system has been almost scrapped. This engineering case vividly demonstrates the critical role of the battery in the PV system and the importance of the battery to the operation of the PV system.