High temperature hot and thunderstorm season, due to a variety of reasons, power generation does not rise but fall. Besides affecting the economic benefits of photovoltaic power stations, it is more likely to endanger the safety of people and property. The inverter manufacturer will discuss with you the error reporting and failure of the five most common types of inverter in summer. We hope that this summer, the power station will be fully turned on!
Low impedance of ground insulation
In cloudy and rainy weather, wet casing is easy to enter water; improper AC wiring may also lead to individual machine water intake; component waterproof box may also be damaged by heat...
The most common error message for these problems is "low impedance to the ground insulation".
Field inspection of DC cable and grounding of components.
1. Check the dc cable
Most of the panel insulation and impedance problems are caused by damage to the dc cables, including cables between components, cables between components and inverters, especially those at the corners of the wall, and cables laid without pipes in the open air, which need to be carefully examined.
In many projects, dc lines are often in contact with component panels, which may cause a certain degree of corrosion on the back of components due to the aging of the outer skin of dc lines for a long time.
Direct contact of cables to the back of the assembly should be avoided; Use anti - corrosion, anti - aging high grade cable.
2. Check the side grounding of the component and the water inlet of the casing
If the photovoltaic system is not well grounded, it will also affect the inverter to accurately detect the component\'s insulation resistance to the ground. Problems that may occur in the field include:
Component support ground
Grounding for a component, generally choose 40 * 4 mm flat or round steel from 10 or 12, the buried depth of 1.5 m underground, photovoltaic modules of grounding resistance is not greater than 4 Ω, to reach the requirements of the grounding resistance, usually by adding drag reduction agent or choose soil buried rate is low.
Protect the earth
There is a ground hole on the right side of the inverter body for repeated grounding to protect the inverter and operator.
The case protection grounding of the inverter can use the earthing pole alone or share a earthing pole with the distribution box
Distribution box side ground
(1) Lightning protection ground
The ac side lightning protection is generally composed of a fuse or circuit breaker and a lightning surge protector. It mainly protects the inductive lightning or direct lightning or other transient overvoltage surges. The lower end of SPD is connected to the grounding arrangement of the distribution box, as shown in the figure below.
(2) The box is grounded
According to the code for acceptance of construction quality of building electrical engineering 6.1.1 the metal frame and base steel of cabinet, screen, platform, box and plate must be grounded (PE) or connected to zero (PEN) reliably. Open doors equipped with electrical appliances, door and frame grounding terminals shall be connected with bare braided copper wire and marked.
The cabinet door and cabinet body of the distribution box should be cross-connected to ensure reliable grounding.
All grounding wires of the equipment in the distribution box shall be connected with PE row, and then PE row shall be drawn out, as shown in the figure below.
Above, from component side, inverter side, distribution box side three aspects of household photovoltaic system grounding.
Over temperature protection
When focusing on the overall performance of the inverter, photovoltaic people usually pay most attention to a series of common problems, such as conversion efficiency, maximum dc voltage, ac output power and protection level. The heat dissipation of the inverter is a problem that pv people tend to ignore, and the power loss caused by the heat dissipation problem or even the over-temperature protection of the machine (load reduction) actually affects the power generation.
The influence of temperature on the power generation of components and even the whole photovoltaic system is very large. In a year, the power generation is not always the highest when the sun is at its best from July to August, but higher in April to June and September to October. Therefore, the ventilation and heat dissipation of the power station is of vital importance in the design, operation and maintenance of the actual power station.
Power grid voltage overshoot
According to the safety regulations, the grid-connected inverter must work within the specified voltage range of the power grid. If the voltage value exceeds the required range of the safety regulations, the inverter must jump off and stop working to ensure the safety of equipment and operators. (note: voltage range of safety gauge in China -- 187V~242V)
Summer is the peak load of electricity, air conditioning and other equipment often open, voltage compared to other seasons low.