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Affected factors on solar power generation

Affected factors on solar power generation

2020-10-25

The power generation rate will be decreased if the solar panel accumulation of dust, but if the frame has mud zone will decrease generation exceed more than 90%.

 

- The mud zone is the accumulation of several or even dozens of layers of floating dust

- Solar Cells blocked by mud zone form a “Buckets effect”

- The effect of floating dust on the power generation of the solar cell is uniform

- In the traditional operation and maintenance robot cleaning work, 90% of the time is to clean the floating dust, but the frame with mud may require additional manual cleaning

- In the traditional manual cleaning work, 90% of the time is to clean the mud zone, even need additional equipment

- The drainage desilter solves the dust accumulation on the frame, so that many solar power stations have less cleaning and even no cleaning

 

1、Pain points of low-inclination photovoltaic power plants

The solar panels of low-inclination photovoltaic power plants most time are flat display on the roof, the installation inclination is 0-5 degree, rain、 snow、 dew、 frost、 clean water and dust are easy to collect at the bottom edge of the framed components. After the water evaporates, a clear mud zone is formed, which adversely affects the power generation and service life of the power plants.

photovoltaic power plants

 

2、The formation principle of mud zone

* solar panel surface accumulation dust is the normal problem of worldwide solar power plants.

* Rainwater washes the surface dust to the bottom edge of the framed components.

* External factors such as wind, vibration, and gravity make it easier for dust to accumulate on the bottom edge of the framed component

* The height difference between the module frame and the glass forms a step, which prevents dust and muddy water from flowing out of the frame and accumulates near the frame. After he water evaporates, a mud zone formed.

 

3、The damage of mud zone

※ Obviously decrease the power generation capacity of the photovoltaic power plants

※ Cause the mud zone form a “Heat Spot”, serious will make a fire damage

※ Cause Anti-Reflection( AR) Coating film oxidize and then form a irreversible “rainbow”.

※ Easy cause solar module Potential Induced Degradation(PID) effect.

※ Accelerate the aging of solar modules and reduce service life.

 

3.1、Decrease the power generation capacity of the solar module

The mud zone blocks the light radiation received by the solar cells, thus cause the current generated by the solar cells in this area to decrease. The solar cells are in parallel connection,  so in mud zone the solar cells form “Buckets effect”, cause whole solar panel power generation been decreased. Research shows that the mud zone contributes more than 90% of the power loss caused by accumulation dust on the surface of most solar modules.

 solar module


3.2、Heat Spot

The amount of radiation received by the solar cells in the mud zone area under the module is relatively smaller than other non-mud zone areas, thus cause result is consistent with the local shadow occlusion, that is, the current generated in this area is significantly smaller than other non-mud zone areas, and eventually leads to Heat Spot.

heat spot


3.3、Anti-Reflection( AR) Coating film oxidize and then form “rainbow”

Glass is prone to hydrolysis under high temperature and high humidity conditions, thus generated sodium hydroxide corrodes the coating layer on the glass surface, and the generated silicic acid gel is attached to the glass surface. At the same time, ultraviolet rays have a greater destructive effect on some of the ionic bonds of the substances in the coating. The simultaneous action of these two factors aggravates the damage of the coating film in the accumulation of water and dust area, thus forming a “rainbow pattern”, which causes the attenuation value of the effective solar transmittance in this area to increase.

anti-reflection coating film oxidize


3.4、Accelerate the aging of solar modules at the mud zone, speed to form PID effect

* The water accumulation time in the mud zone area under the frame assembly is significantly longer than other areas. The mud zone seriously reduces the electric resistance of the glass surface, and the leakage current at the mud zone will increase significantly, which is more easy to cause PID effect, those leads to battery aging in the mud zone obvious faster than other regions.

* The “heat Spot” in the mud zone will fast speed this are aging.

solar panels


3.5、The mud zone is easy to accumulate oil

The commercial photovoltaic power plants are most in the industrial area or traffic busy places, the concentration of organic matter such as automobile exhaust gas, industrial exhaust gas, and boiler fuel oil in the air in a local area is high, and it is easy to accumulate in the dust deposit on the surface of the component.  Along with the rainfall forms a mud zone and organic matter accumulates in the mud zone, then combines with the glass anti-reflection film to form stubborn oil stains. Mud can be cleaned off, but oily stains is difficult to clean.     

mud zone


4、Existing mud zone operation and maintenance plan and shortcomings

The cleaning scheme is generally used for when the solar module accumulate dust

Manual cleaning:

Consuming time、laborious、water and material

Roof climbing to do cleaning is hard and not safe

Robot cleaning:

Large investment

high requirements for solar module framework array consistency

Equipment needs maintenance






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