Non-Idealities in the I-V Characteristic of the PV Generators: Manufacturing Mismatch and Shading Effect

During the last years, European government remuneration polices promoted the realisation of photovoltaic systems integrated with the structures instead of on ground photovoltaic (PV) plants. In this context, in rural areas, greenhouses covered with PV modules have been developed. In order to interdict the building of greenhouses with an amount of opaque panels on covering not coherent with the plant production, local laws assigned a threshold value, usually between 25% and 50%, of the projection on the soil of the roof. These ranges seem not to be based on scientific evaluation about the agricultural performances required to the building but only on empirical assessments. Purpose of this paper is to contribute to better understand the effect of different configurations of PV panels on the covering of a monospan duo-pitched roof greenhouse in terms of shading effect and energy efficiency during different periods of the year. At this aim, daylighting and insolation analysis were performed by means of the software Autodesk<sup>®</sup> Ecotect<sup>®</sup> Analysis (Autodesk, Inc., San Rafael, CA, USA) on greenhouse model with different covering ratio of polycrystalline photovoltaic panels on the roof.

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Research on double-faced jacquard fabric with compound full-backed structure of three wefts

Industria Textila ◽

10.35530/it.072.05.1725 ◽

2021 ◽

Vol 72 (05) ◽

pp. 491-502

Author(s):

LINLIN BAI ◽

JIU ZHOU

Keyword(s):

Design Method ◽

Single Layer ◽

Colour Difference ◽

Compound Structure ◽

Critical Position ◽

Shading Effect ◽

Transition Effect ◽

Structure Database ◽

Step Number ◽

Colour Effect

Weft-backed structures with compound weft colours can express the mixed colour effect. However, this structure is not suitable for jacquard fabrics with a double-faced shading effect in the traditional single layer design mode. Taking twenty-thread sateen with a step number (S) of 7 as an example, this paper investigates a design method for compound full-backed structure with three shaded-weave databases (SWDs) by selecting the primary weaves (PWs), designing the compound full-backed technical points and establishing the compound structure database with three SWDs. With this design method, a double-faced shading effect in combination with non-backed and full-backed effects on different sides of the jacquard fabric at the same position is generated. The fabric colour card was produced with three SWDs and three sets of different coloured wefts, and their colour values were measured, followed by an analysis of the compound structures on the reverse side, lightness, colour purity and colour difference (DE*ab) of the specimens. The results showed that the three covering effects on the reverse side, partly covered, critical position and totally covered, could be adjusted by controlling the step number and the transition direction of PW-C. For the specimens on the edges of the fabric colour card, their lightness and colour purity values showed a uniform transition effect along with the shading process; their colour differences ranged from 1.23 to 3.69, both in the range of 2–5, and showed a trace or slight colour difference between two adjacent fabric specimens, indicating that the colour shading effect with the three SWDs is stable.

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