Solar photovoltaic module

Abstract

In the present invention a new solar photovoltaic module is proposed comprising a solar cell comprising a silicon layer having a first (1 a) surface and a second surface (1a) opposite to said first surface. The solar cell further comprises a passivating layer stack (2) comprising a heterogeneous layer (4) arranged on said first surface and / or on said second surface. The heterogeneous layer (4), having a back surface (3) and a front surface (5), comprises a non-conducting matrix (4b) having a refractive index being lower than 3.0. The heterogeneous layer further comprises inclusions 4a of at least one conductive material in said matrix 4b, and at least some of said inclusions (4a) extend from said back surface (3) to said front surface (5) of the heterogeneous layer (4) for electrically connecting the surfaces (3,5) of the heterogeneous layer.

Description

technical field [0001] The invention relates to the field of solar cells. More specifically, the present invention relates to a solar photovoltaic module comprising silicon-based photovoltaic elements composed of heterogeneous layers. Background technique [0002] Today's solar cell production is dominated by two main silicon solar cell structures. These are aluminum-back field (Al-BSF) solar cells and passivated emitter back field contact solar cells (PERC), which together accounted for >80% of world production in 2014: SEMI (2015, 31.08.2015). International Photovoltaic Technology Roadmap (ITRPV): http: / / www.itrpv.net / Reports / Downloads / 2014 / . [0003] Such as Figure 1a As shown in Figure 1b, the PERC cell is very similar to the Al-BSF cell, but the performance of the PERC cell is improved due to the dielectric layer on the back side, which passivates the surface of the silicon wafer, if the dielectric layer is sufficient thick, it can act as an internal mirror...

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Problems solved by technology

[0020] Although SHJ solar cells have achieved impressive results, they have two major disadvantages: Due to the temperature sensitivity of a-Si:H, SHJ solar cells cannot be heat-treated at temperatures above 300 °C, which makes They are incompatible with industrial metallization schemes: S.De Wolf and M.Kondo: "Boron-doped a-Si:H / c-Siinterfacepassivation: Degradation mechanism", Applied Physics Letters, vol.91, pp.112109 / 1 -3, 2007 and S.De Wolf, A.Descoeudres, Z.C.Holman, and C.Ballif, "High-efficiency silicon heterojunction solar cells: a review", Green, vol.2, DOI 10.1515 / green-2011-0039, 2012

The second disadvantage is caused by the parasitic light absorption in a-Si:H thin film and transparent conductive oxide (TCO), which causes about 3mA / cm 2 current loss

[0038] 3. In most cases, even after annealing, the Si layer is not fully crystalline but partially amorphous

[0042] 5. Since the refractive index of amorphous or partially crystalline Si is very similar to that of Si flakes, it does not act as an internal reflective layer

This limits the performance of the contact layer when used on the backside, or requires additional layers such as transparent conductive oxide (TCO) and additional process steps such as planarization, which further increases cost and process complexity

[0043] 6. Diffusion of dopants through the tunneling oxide will deteriorate the electrical properties of the tunneling oxide layer, especially leading to a decrease in the passivation ability of the silicon wafer

However, high doping concentration will still cause the absorption of free carriers, thereby reducing the short-circuit current density

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