Off-grid photovoltaic power generation system is usually composed of solar energy components, controllers, inverters, battery groups and support systems. It is suitable for regions where there is no grid connection or unstable grid power. The resulting dc power can be stored directly in a battery pack to provide power at night or on cloudy or rainy days.
When designing off-grid photovoltaic power generation system, it should be handled flexibly. Photovoltaic off grid power generation system can not solve all the power consumption problems, and it can only save electricity when encountering multiple continuous rainy days. Off-grid inverter is no uniform standard, also do not need compulsory certification, so the products on the market are very different. The quality and price of the products are quite different. They should complain or report to the police when they encounter fake or inferior products.
How to solve the common problems of off-grid photovoltaic power generation system design?
1. Components, inverters, batteries should be matched in design, and no one should be too large or too small. When the novice design, the power consumption is often too large, such as 1P air conditioning operation for 12 hours, 10 degrees of electricity, the 300W refrigerator runs 24 hours, calculated as 7.2 degrees of electricity, resulting in excessive capacity of the battery, high system cost. When designing battery capacity, it is best to fill the specifications in 2 days.
2. The output voltage and current phase and amplitude of each inverter are not the same. The inverter does not support the output terminal parallel, and the output end of the inverter is not connected.
3. The load is the load of the elevator, and it can not be connected directly with the output of the inverter, because the motor reverses when the elevator is down. It will produce an anti electromotive force. When the inverter is entered, the inverter is damaged. If it is necessary to use the off grid system, it is recommended to add a frequency converter between the inverter and the elevator motor.
4. The photovoltaic micro-network system with complementary input of municipal electricity needs to be insulated. If there is leakage current from the components to the ground, it will be transmitted to the municipal electricity, causing the leakage switch of municipal electricity to trip off.
5. The voltage of the component is matched with the voltage of the battery. The PWM type controller is connected by an electronic switch between the solar module and the battery, and there is no inductor in the middle. The voltage of the component is 1.2-2.0 times of the voltage of the battery. If it is a 24V battery, the voltage of the component is between 30-50V. The MPPT controller. There is a circuit with a power switch tube and an inductor. The voltage of the component is 1.2-3.5 times of the voltage of the battery. If the battery is 24V, the input voltage of the component is between 30-90V.
6. The output power of the module is similar to that of the controller. For example, a 48V30A controller has an output power of 1440VA, and the power of the module should be about 1500W. When selecting the controller, first look at the voltage of the battery, then the component power is divided by the battery voltage, that is, the output current of the controller.
7. The charging current of the battery is generally 0.1C-0.2C, maximum not more than 0.3C, for example, the 1 section lead acid battery 12V200AH, the charging current is generally between 20A and 40A, and the maximum can not exceed 60A; the discharge current of the battery is generally 0.2C-0.5C, the maximum no more than 1C, the 1 section 12V200AH lead-acid storage pool, the maximum output power not more than 2400W. Different manufacturers, different models, the specific value is also different, the design must ask the manufacturer for instructions.
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