product quality
Quality problems of accessories such as brackets and cables
In the power station, parts such as expansion bolts or brackets are rusted, or the special cables for photovoltaics are not used.
Rusty nut
Bracket port is rusted
Photovoltaic special DC cable
problem consequences
The quality of the bracket accessories is not high enough. In the long run, it will affect the overall stability of the power station. It may be that the brackets are loosened due to the rust and falling off of the parts, which may affect the inclination of the power station and reduce the power generation of the power station. Collapse, or the stability of the counterweight becomes poor, and it is easily blown over by the wind.
For power stations that do not use photovoltaic special cables, in the subsequent long-term operation, the exposed cables will be corroded by the sun and rain for a long time, which is prone to exposed copper wires, resulting in electric leakage and electric shock accidents; and non-photovoltaic special cables will also increase the power Losses during transmission, resulting in a loss of power generation.
Install service class
1 occlusion problem
A 5-kilowatt photovoltaic power station installed by a customer in Shandong Province has a solar water heater on the southwest side. Between 13:00 and 16:00 in the afternoon, the front row of photovoltaic arrays is shaded by the water heater, covering a total of 7 photovoltaic modules. The measured power loss of the power station is about 30%.
foreign object occlusion
② A 20-kilowatt photovoltaic power station installed by a customer in Hebei Province, the lower part of the rear-row modules was blocked by the front-row modules throughout the day, and the measured power loss of the rear-row modules was about 90%.
self occlusion
problem consequences
Since the cells in a module are all connected in series, and several modules of each DC module are also connected in series, blocking a module or even blocking one of the cells of a module will greatly affect the power output of the entire string. Impact.
2 Installation angle problem
Some photovoltaic power stations are not constructed according to the local optimal installation inclination (excluding the case of tiling with the roof angle)
It can be seen from the above figure that if the installation inclination is wrong, the power generation can be reduced by more than 30% at most.
3 system matching problems
In some power stations, the matching of DC strings and inverters is unreasonable.
Consequences of the problem: resulting in a drop in power generation.
Suggest:
When the same MPPT is connected to more than two DC strings, the input voltage and current of each channel must be kept consistent, otherwise it will cause a large parallel loss. That is, the model and number of components in each string of the two strings should be the same, and the angle of the components should be the same.
Inverters with a capacity of 5 kW and above on the market have more than two MPPT inputs. Each MPPT can be regarded as a separate inverter module, and the power parameters between the two MPPTs do not affect each other. Therefore, it is necessary to put components with the same string parameters into one MPPT, and separate components with inconsistent string parameters into two different MPPTs to ensure that each channel has the maximum power output.
4 Power station counterweight problem
problem consequences
Insufficient counterweights can put the power station at risk of being overturned by strong winds. At present, in order not to damage the roof structure, most of the current flat-roof photovoltaic projects use the cement block weight method. Under the same friction coefficient, the greater the pressure, the larger the contact area between the pressure block and the roof, and the greater the friction force. The bigger it is, the stronger the wind resistance is. If the counterweight is insufficient, the power station will be displaced when the wind is strong, and eventually the power station will fall.
5 Inverter installation problems
Some inverters are installed without enough space for heat dissipation.
Inverter installation safety distance is too small
problem consequences
The optimal operating temperature of electrical equipment is 25°C. As the temperature rises, the loss of electrical energy will increase, and the inverter itself will reduce the output power to protect the equipment, thereby causing the overall power generation of the power station to decrease. If the inverter heats up continuously due to poor heat dissipation, the internal circuit may be overheated and burnt, which may even cause a fire.
6 AC cable wiring is not standardized
In some power stations, the AC cables are not well connected, and the connection is virtual.
AC air switch burned out
problem consequences
①Virtual connection of cables will lead to excessive line loss and affect the power generation of the power station.
②The cable is connected in a virtual way, and the virtual contact will continue to heat up. After a long time, the cable and accessories will be burned, and it will cause a fire in serious cases.
After-sale service
1 Power station cleaning problem
Most of the power stations have a lot of dust, which seriously affects the power generation of the power station.
problem consequences
According to a month-long dust shielding experiment conducted by Inneng in 2014, the power generation of modules cleaned every week was 3.1% higher than that of uncleaned modules. The air quality was good at the time, and it rained a few times during the period. It is inferred from this that in areas with large sandstorms, smog, and less rain, the difference in power generation between frequently cleaned and unclean components must be much higher than 3%.
2 power station monitoring problems
Some power stations have not established monitoring connections.
The direct economic loss is nearly 1,000 yuan.
problem consequences
It is possible that problems in the power station cannot be found in time, resulting in a reduction in power generation revenue. After the monitoring of the power station is connected, after-sales maintenance personnel and owners can remotely monitor the operation of the power station. Once problems occur in the operation of the power station, they can check and deal with them as soon as possible to reduce power generation losses.