The battery capacity is determined according to the user's power consumption or desired standby time.
The task of the battery is to ensure the normal power consumption of the system load when the amount of solar radiation is insufficient. For important loads, to be able to ensure the normal operation of the system within a few days, the number of consecutive cloudy days should be considered.
For general loads such as solar street lights can be selected within 2 to 3 days based on experience or need. Important loads such as communication, navigation, hospital rescue, etc. are selected within 3 to 7 days.
Also consider the installation location of photovoltaic power generation system, if in a remote location, the battery capacity should be designed to be larger, because it takes a long time for maintenance personnel to reach the site.
In practice, some mobile communication base stations due to high mountains and far away, it is very inconvenient to go once, in addition to the configuration of the normal battery pack, but also equipped with a set of backup battery pack, for the general poor families, the main consideration price, then do not have to consider the rainy days, the sun is good when more use.
When the sun is bad less use, no sun is not used. When choosing the load, try to use energy-saving equipment, such as LED lights, inverter air conditioners. The design of battery mainly includes the design calculation of battery capacity and the design of series-parallel combination of battery pack.
In the photovoltaic power generation system, most of the batteries used are lead-acid batteries, taking into account the life of the battery, generally take the depth of discharge is between 0.5-0.7. Battery design capacity = (load average daily power consumption * number of consecutive cloudy days) / battery discharge depth.
Battery charging current is generally 0.1C-0.2C, the maximum does not exceed 0.3C, for example, 1 lead-acid battery 12V200AH, charging current is generally between 20A and 40A, the maximum can not exceed 60A; battery discharge current is generally 0.2C-0.5C, the maximum does not exceed 1C, 1 12V200AH lead-acid battery, the maximum output power does not exceed 2400W, different manufacturers, different models, the specific value is not the same, the design should ask the manufacturer for instructions.
