Equipment Parameters
System Design
Common Faults
  • Equipment Parameters

    1. What does connecting different MPPTs mean? Under what circumstances is access possible?

    Answer: A string inverter usually has more than 2 MPPTs, and each MPPT usually comes with 1 or more strings. Each MPPT is independent and has the ability to track and control changes in output voltage and current, with the greatest advantage of keeping the array in the maximum output operating state. We refer to it as maximum power point tracking. Connect different MPPTs in situations such as multiple orientations, shadows, inconsistent string lengths, and angles.

    2. Under MPPT, there is an error in the two open circuit voltages of two strings. Does MPPT track high voltage or low voltage?

    Answer: In the case of voltage parallel mismatch, the maximum power tracking point of MPPT is different, and the low voltage will pull the high voltage down, affecting the overall output power.

    3. What is the better rated voltage of the inverter for DC string voltage?

    Answer: In theory, it is close to the maximum voltage of MPPT.

    4. Does the maximum DC working current of 25/25adv indicated on the inverter mean that each MPPT can have a working current of 25A? Can there be a total current of 50A?

    Answer: It refers to the maximum input current of 25A per MPPT. If each MPPT has 2 strings, the maximum input current for each string is 12.5A; If a string is used, the string current should be less than 25A.

    5. Can components with different powers never be connected in series? or can it be connected in series if the power difference is not significant? How much power difference can be connected in series?

    Answer: Xiaogu does not recommend doing this because different power of the components represent different working currents. If connected in series, the entire string will follow the minimum component current. The more power difference, the greater the current difference.

    6. What is the difference between maximum short-circuit current and maximum input current?

    Answer: The maximum allowable current measured by short circuiting the positive and negative poles is the maximum short-circuit current, and the maximum working current refers to the maximum output current value allowed for series operation.

    7. Can the DC input of the inverter be calculated based on the rated voltage of the component?

    Answer: The calculation can be carried out in accordance with the provisions of the photovoltaic power station design code GB50797. It is necessary to meet both the calculation based on the open circuit voltage of the components (maximum number of connected components per string) and the calculation based on the working voltage of the components (based on the MPPT efficiency of the inverter). The specific situation can be determined according to the actual situation.

  • System Design

    1. Do I need to change the inverter to convert the power station into a self generated surplus power grid?

    Answer: The connection of surplus electricity to the grid or full grid mainly depends on whether the grid connection point is at the front or back end of the load, and has nothing to do with the inverter. There is no need to modify the inverter. If the previous application was for full internet access, it is necessary to reapply for residual internet access from the power supply company.

    2. Can the south slope and north slope share the same inverter?

    Answer: It is possible to share the same inverter, provided that components from different slopes need to be placed in different MPPTs, and it is necessary to ensure that the number and orientation of each component under the same MPPT are consistent.

    3. Can a 30kW inverter be paired with a 35kW component?

    Answer: The maximum input power of the 30kW inverter GW30K-MT is 39kW, and it can be connected to a 35kW component. The specific amount of configuration needs to be designed according to the actual situation of the project.

    4. Will the power exceed if the voltage of each string does not exceed? For example, a 15kW inverter uses three MPPTs, each 5kW.

    Answer: In general, the designed component power will exceed the rated power of the inverter, while the voltage will not exceed the maximum system voltage of the inverter. 15KW inverter, if it is a 3-way MPPT, can be designed as 2 or 3 series, both of which can be designed to exceed the rated power of 15KW.

    5. What is the size of the circuit breaker used for a 50kW inverter?

    Answer: The maximum output current of a 50kW inverter is 80A, and the circuit breaker can be designed to be 80A * 1.25 times the value. Choose a 100A one.

    6. What is the size of the air switch for a 20kW inverter and 380V?

    Answer: When considering an overload of 1.1 times for a 20kW system, the maximum AC output power is 22kW. The corresponding current is 22/(3 * 0.4)=18.3, and circuit breakers are usually selected based on 1.25 times the rated current. An air switch with a rated current of around 40A is sufficient.

    7. Can a 25kW SMT inverter match a grid frequency of 50.02Hz?

    Answer: It can be matched. The inverter has the ability to withstand system frequency anomalies to a certain extent, and can operate according to regulations within the frequency range of the power grid, with a frequency setting range of 48.5Hz-50.5Hz.

    8. Can the 1kW182 component really generate 1500 kWh of electricity per year?

    Answer: This is achievable. There are two situations: 1. In resource areas where the annual equivalent utilization hours are greater than 1500 hours; 2. In resource areas where the annual equivalent utilization hours are less than 1500 hours, tracking brackets or other auxiliary technologies can be used.

    9. How large can a 10kW ET energy storage inverter be connected to a lithium battery? Is it equipped with a lithium battery?

    Answer: The battery of a 10kW ET energy storage inverter needs to be optional, and equipped with Goodway battery Lynx S can reach a maximum of 20kWh.

    10. What are the suggestions for lightning protection in the entire system?

    Answer: The lightning protection of the system includes direct lightning and induced lightning. Direct lightning can be grounded through the metal frame, bracket, and original building structure metal objects of photovoltaic modules. Induced lightning can be connected through equipotential connection, magnetic shielding, and installation of SPD. For specific details, please refer to GB/T 36963 Technical Specification for Lightning Protection of Integrated Photovoltaic Building Systems.

    11. If distributed photovoltaic power stations are built together with China Mobile's 4G and 5G transmission base stations (without reflection), will it affect power generation? Will it attract more thunder?

    Answer: Due to the particularity of base stations, they need to be built at a high altitude. Photovoltaic power generation is one of the multiple complementary energy sources for supplying power to base station equipment. There are many factors that affect the power generation of photovoltaic power stations. In terms of self design, such as component orientation, angle, line loss, spacing, etc., and external factors such as shadows, the base station is a load for photovoltaic power stations and does not affect power generation. Even if no load is applied, it does not affect power generation.

    A photovoltaic power station is not the highest point, and the lightning rod at the top of the base station is the highest point. The lightning rod will introduce lightning charges into the ground. The photovoltaic power station together with the base station will not actively induce lightning, but will provide lightning protection through grounding, SPD, and other methods.

    12. How much does the angle between the component and the horizontal plane affect the power generation efficiency?

    Answer: The power generation efficiency varies in different latitude and longitude regions. Taking Jinan as an example (facing south, under the same conditions, 30 degrees is the optimal inclination angle, without losing power generation), if the component inclination angle is 50 degrees, the power generation loss is 4%; The inclination angle is 40 degrees, resulting in a 0.9% loss of power generation; The inclination angle is 20 degrees, resulting in a 1.3% loss of power generation; The inclination angle is 10 degrees, resulting in a 4.6% loss of power generation.

  • Common Faults

    1. What should I do if I go offline?

    Answer: First, check the "Traffic Recharge" section on the homepage of the Xiaogu Cloud Window APP to see if the traffic has expired. If it has not expired, plug and unplug the module again, restart the machine, and observe. If it is still offline, call the after-sales hotline at 400 998 1212 (7:30-19:30 every day), and a professional after-sales team will investigate for you.

    2. How to restart the inverter module?

    Answer: Re plug the module and restart the machine.

    3. Does the adjustment of inverter safety regulations have an impact on power generation?

    Answer: Improper adjustment of safety regulations may cause the grid voltage to exceed the limit.

    4. Relay detection abnormality

    Answer: 1) Disconnect the inverter DC circuit breaker

    2) Wait for the inverter LCD/LED screen to not light up

    3) Reconnect the DC circuit breaker and confirm again

    4) If the malfunction occurs again, please contact the after-sales service by phone: 400 998 1212 (7:30~19:30 every day)

    5. DC bus voltage too high

    Answer: 1) Disconnect the inverter DC circuit breaker

    2) Wait for the inverter LCD/LED screen to not light up

    3) Reconnect the DC circuit breaker and confirm again

    4) If the malfunction occurs again, please call the after-sales hotline: 400 998 1212 (7:30~19:30 every day)

    6. When a power outage occurs in a power station, should the photovoltaic side switch be turned off first or the grid side switch be turned off first? Which side of the switch should be closed first when connecting to the grid for power transmission?

    Answer: When the photovoltaic power station experiences a power outage, first turn off the DC (component side) and then turn off the AC (inverter side); When delivering power, turn on AC first and then DC. Turn off AC first and then DC; Turn on AC first, then turn on DC. Communication always comes first

    7. On a sunny afternoon, there was a peak shaving phenomenon in the MPPT current of the inverter. What is the reason for this?

    Answer: The selected component current exceeds the maximum input current of the inverter: 1) The component has a positive tolerance, and peak shaving may occur in STC or better than STC conditions; 2) The components are tested according to STC standards before leaving the factory, and there may be a few cases of exceeding STC standards outdoors.

    8. Under the same MPPT, there are 18 components in each of the two strings. If one of the components is obstructed by 2, will it affect the normal power generation of the other string of components?

    Answer: The MPPT algorithm finds the maximum power point by adjusting the voltage. In this case, there will be two peak power points, and the MPPT tracking point will be lower than normal, reducing power generation efficiency.

    9. What's the reason why the better the weather, the less electricity generation?

    Answer: The power generation of photovoltaic power plants in summer may not be as high as during clear spring or autumn, because the sustained high temperatures in summer have a significant impact on the components. When the temperature rises, the output power of the component will decrease, and for each degree of increase, the power generation will decrease by about 0.44%.

    10. What is the reason why the current is not as high as the current when there are more string blocks?

    Answer: Under the same conditions, as the number of components increases, the voltage is superimposed, and the current remains unchanged. This abnormal situation may be caused by string mismatch (inconsistent model, inconsistent attenuation, inconsistent line loss, shadow occlusion, etc.).

    11. Is the grounding of the inverter and the grounding of the casing connected together?

    Answer: The grounding of the inverter and the grounding of the casing are not connected at the same point and need to be separated. The former is working grounding (which can maintain the non fault phase to ground voltage unchanged; can ensure the accuracy of relative low voltage measurement in a system; discharge lightning current to the ground during lightning strikes), while the latter is protective grounding (to ensure personal safety and avoid or reduce the harm of accidents, protective grounding is often used in electrical engineering).

    12. What is the reason for the leakage protection tripping of the distribution box, normal insulation of the AC cable, tripping once every morning, and normal circuit?

    Answer: There may be two reasons:

    1) Improper selection and insufficient preservation value;

    2) There is leakage in the circuit, which may be related to grounding or insulation.

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and energy-saving photovoltaic inverter solutions