What are the factors affecting the efficiency of photovoltaic modules and

Polaris solar PV net news: first, the attenuation of the components:

Photo-induced effect of attenuation, also known as S-W. A-Si:H film a long time strong light or electricity through, in its internal defects and the film’s performance, called the StaEbler-Wronski effect (D.L.Staebler and C.R.Wronski was first discovered. Personal think PV component of attenuation actual is wafer performance of attenuation, first wafer in long-term has oxygen bad border in the will occurred slow chemical reactions was oxidation, to reduced performance, this is component long-term attenuation of main reasons; in vacuum forming process in the will to must proportion doping boron (hole) and p (to body), improve wafer of carrier migration rate, to improve component performance, but boron as deficiency electronic Atomic will and oxygen Atomic (to body) occurred composite reaction, reduced carrier migration rate, to reduced component of performance, This is the main reason about components Attenuation of 2% for the first year.

Attenuation of the components are divided into:

1 due to disruptive factors have contributed to the sudden decline in the power and destructive factors mainly refer to components in the welding process the welding side, package process exists for lack or components during installation of the handling, mishandling, or components used in the process crash caused by hail component cracked, cell serious fragmentation phenomena;

2, initial components of light attenuation, PV module power output at the beginning of larger declines occurred within the first few days of use, but then stabilized, generally below 2%;

3, the aging degradation of a component, that is, in the long run extremely slow power loss phenomena in annually decay in 0.8%, attenuation of 25 does not exceed 20%; 25 efficiency quality assurance is already in Japan and Germany on the components of two solar companies are confirmed. Domestic PV modules have been able to meet the requirements after 2012, production of photovoltaic modules and equipment and materials for basic imported from West Germany.

Second, the efficiency of the system:

(Think decay regardless of system efficiency, and reduce system efficiency, we can be achieved through local or equipment maintenance requirements, such as thermal power stations, hydroelectric plants, not to mention the attenuation of this statement.

Are the key factors affecting the power generation efficiency, system efficiency of main factors to be considered are: dust, rain shelter caused by inefficient, thermal efficiency, component series mismatch is less efficient, inverter, DC AC power loss parts cables power losses, tracking systems, transformer power loss of precision, and so on.

1) caused by dust, rain shelter inefficient

Large-scale photovoltaic power plants are generally located in the Gobi region, large sand, and rarely consider managers cleaned array components are frequently under normal circumstances, attenuation values: 8%;

2) thermal efficiency

Solar component will for temperature changes and output voltage reduced, and current increases, component actual efficiency reduced, electricity reduced, so, temperature caused of efficiency reduced is must to consider of a important factors, in design Shi consider temperature changes caused of voltage changes, and according to the changes select component series number, guarantee component can in most time within work in maximum track power range within, consider 0.45%/K of power changes, and consider the months irradiation volume calculation weighted average value, Can be calculated from the weighted average value, there are some differences due to different ambient temperature, system there were certain differences in temperature reduce system efficiency values for 3%.

3) component series mismatch is less efficient

Due to production problems, resulting in power and current there is a certain deviation between different components, single battery pack has little effect on the system, but after grid-connected photovoltaic power station is made up of many solar module and parallel composition, between power and current bias for PV power generation efficiency will have some effect. Of inconsistent components in series as the current efficiency, select the reduce the efficiency of 2%.

4) DC cable power loss

According to the design experience, conventional 20MWP project uses special cables for photovoltaic grid-connected PV power generation is about 350km, combiner box to DC power cable distribution cabinets (General use model ZR-YJV22-1kV-2*70mm2) amount of about 35km, DC portion of the cable was obtained by calculating loss 3%.

5) inverter power loss

Current domestic production of high power inverter (500kW) efficiency are up 97.5% system efficiency, grid-connected inverters without transformer type, through the double split transformer isolation 2 parallel inverter, the inverter is not considered internal transformer efficiency, inverter power loss can be 97.5%, 97.5%.

6) AC power cable loss

Because of grid-connected photovoltaic power stations generally use local boost for AC line cable is usually a high voltage cable, that part of the loss is small, calculated the Exchange portion of the cable loss is about 1%.

7) transformer power loss

Transformer for a mature product, selection of high efficiency transformer, transformer efficiency is 98%, that is about 2% power loss.

Power loss in the above sections, measure the efficiency of the system: the loss of dust component, component temperature efficiency losses, component mismatch loss, voltage drop, inverter efficiency, step-up transformer efficiency, loss of the AC line, you can calculate efficiency of PV systems:

System efficiency: η = (1-8%) * (1-3%) * (1–2) * (1-3%) * (1-2.5%) * (1-1%) * (1–2) =80.24%.

Following this analysis, we can draw the efficiency of photovoltaic grid-connected power systems typically 80%.

Original title: what are the factors affecting the efficiency of photovoltaic modules and systems?

Posted in Solar Charger.