Campbell CR-PVS1, Руководство по эксплуатации продукта

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CR-PVS1 PV Soiling Loss Index RTU
9
FIGURE 7-5. Change in SLI after a cleaning event. Both modules were
cleaned at a time corresponding to the record number 650.
7.2 Soiling Loss Index Details
In terms of quantities that can be measured directly from a PV panel, soiling
loss index (SLI) is defined as the loss in the irradiance reaching the solar cells
of a PV panel. If all other factors are the same, this loss is primarily due to the
loss in transmission properties of the glass as a result of soiling.
The irradiance is calculated from short-circuit current as
𝐺𝐺
𝑒𝑒𝑒𝑒𝑒𝑒
= 𝐼𝐼
𝑆𝑆𝑆𝑆
[1
− 𝛼𝛼
(
𝑇𝑇 − 𝑇𝑇
0
)]
𝐼𝐼
𝑆𝑆𝑆𝑆 , 𝑆𝑆𝑆𝑆𝑆𝑆
7-1
Where G
eff
: effective irradiance reaching the solar cells
I
SC
: measured short-circuit current of the panel
I
SC,STC
: short-circuit current at standard test conditions (STC)
T: back-of-panel temperature
T
0
: back-of-panel temperature at STC, typically 25 °C
α: temperature coefficient of short -circuit current
The SLI uses the effective irradiances of a clean reference panel and a dirty test
panel. It is defined as
𝑆𝑆𝑆𝑆𝐼𝐼 = � 1 −
𝐺𝐺
𝑒𝑒𝑒𝑒𝑒𝑒 , 𝑆𝑆𝑒𝑒𝑇𝑇𝑇𝑇
𝐺𝐺
𝑒𝑒𝑒𝑒𝑒𝑒 , 𝑅𝑅𝑒𝑒𝑒𝑒
� × 100%
7-2