CN113718173A

CN113718173A - Metal plate, metal roof and BIPV system

Info

Publication number: CN113718173A
Application number: CN202110925428.7A
Authority: CN
Inventors: 谭小春; 朱疆
Original assignee: Xian Longi Green Energy Architecture Technology Co Ltd
Current assignee: Longi Solar Technology Co Ltd
Priority date: 2021-08-12
Filing date: 2021-08-12
Publication date: 2021-11-30

Abstract

The invention discloses a metal plate, a metal roof and a BIPV system, and relates to the technical field of photovoltaics, so that the service life of the metal plate is prolonged. The metal plate comprises a steel substrate and a coating arranged on the surface of the steel substrate; the chemical components of the steel substrate comprise C, Mn, P, S, Cr, Ni, Cu, Mo, and the balance of iron and inevitable impurities; the chemical components of the plating layer comprise Al, Mg, and the balance of Zn and inevitable impurities. The metal plate and the metal roof provided by the invention are used for manufacturing a BIPV system.

Description

Metal plate, metal roof and BIPV system

Technical Field

The invention relates to the technical field of photovoltaics, in particular to a metal plate, a metal roof and a BIPV system.

Background

Building Integrated Photovoltaics (BIPV) is a technology that integrates solar power (photovoltaic) products into buildings.

At present, the quality guarantee time of the linear power output of the photovoltaic dual-glass assembly reaches 30 years, and the actual service life of the photovoltaic dual-glass assembly is longer than 30 years. In the prior art, the service life of a metal roof made of a carbon steel metal plate is shorter than 20 years, and the service life of the metal roof and the service life of a photovoltaic module are not matched, so that the service life of the whole BIPV system can be greatly shortened.

Disclosure of Invention

The invention aims to provide a metal plate, a metal roof and a BIPV system so as to prolong the service life of the metal plate.

In a first aspect, the present invention provides a metal plate. The metal plate comprises a steel substrate and a coating arranged on the surface of the steel substrate;

the chemical components of the steel substrate comprise C, Mn, P, S, Cr, Ni, Cu, Mo, and the balance of iron and inevitable impurities;

the chemical components of the plating layer comprise Al, Mg, and the balance of Zn and inevitable impurities.

When the technical scheme is adopted, on one hand, the plating layer of the metal plate contains Al and Mg elements. In the atmospheric environment, Al and Mg in the plating layer can be oxidized by themselves to form a compact oxide film after contacting with air. The dense oxide film is located on the surface of the plating layer, namely the surface of the metal plate, and can be used as a physical barrier to protect the plating layer and the steel substrate from corrosion. On the other hand, the steel substrate of the metal sheet contains elements of Cr, Ni, Cu, Mo and P. When the plating layer is consumed and the surface of the steel substrate is in contact with the atmospheric environment, Cr, Ni, Cu, Mo and P elements can be in contact with air to generate chemical reaction, and a rust layer is formed on the surface of the steel substrate. The rust layer has good compactness and strong adhesive force with the steel substrate, and can prevent corrosive media in the air from contacting the steel substrate, thereby inhibiting the corrosion problem of the steel substrate and prolonging the service life of the steel substrate.

The invention combines the plating layer and the steel substrate together. In the actual use process of the metal plate, an oxidation film on the surface of the plating layer, the plating layer used as a sacrificial anode, a rust layer on the surface of the steel substrate and the steel substrate are sequentially used as protective structures to play a role in resisting corrosion. Under the combined action of the multilayer protection structure, the service life of the metal plate can be greatly prolonged, so that the service life of the metal plate is longer than 30 years.

In some implementations, the chemical composition of the steel substrate also includes Si. In the process of forming a coating by dip plating of a steel substrate, Si can inhibit the reaction of impurity element Fe in the steel substrate and Al in a plating solution (coating) and avoid the formation of intermetallic compounds of Fe and Al. And the intermetallic compound of Fe and Al has strong hard brittleness, so that the problem of cracking is easily caused in the forming processing of the steel substrate, and the adhesive force between the coating and the steel substrate is reduced. According to the invention, Si is added into the steel substrate, so that the problems that the plasticity of the plating layer is reduced by the multi-element intermetallic compound when Si is added into the plating solution and the plating layer is easy to crack during complex forming can be avoided, the plasticity of the plating layer can be improved, and the performance of the plating layer can be ensured. On the other hand, the melting point of the plating solution can be prevented from rising, the energy consumption of the dip plating process can be prevented from increasing, the energy consumption of the dip plating process can be effectively controlled, and the cost can be reduced.

In some implementations, a ratio of 100 times a mass percentage of Si in the steel substrate to a mass percentage of Al in the plating layer is 1.8 to 4.2. In this case, the amount of Si added is well matched with the amount of Al added, and the reaction of Fe and Al can be suppressed well.

In some implementations, the ratio of 100 times the mass percent of Si in the steel substrate to the mass percent of Al in the coating is 2-3.5. In this case, when the amounts of Si and Al added satisfy the above ranges, the reaction of Fe with Al can be suppressed more favorably, and the adverse effect of an excessively large Si content on the steel substrate can be avoided.

In some implementations, the chemical composition of the steel substrate includes: 0.02 wt% -0.08 wt% of C, 0.20 wt% -1.60 wt% of Si, 0.60 wt% -1.80 wt% of Mn, 0.01 wt% -0.09 wt% of P, less than 0.025 wt% of S, 0.15 wt% -3.60 wt% of Cr, 0.15 wt% -3.60 wt% of Ni, 0.15 wt% -0.60 wt% of Cu, 0.15 wt% -0.60 wt% of Mo, and the balance of iron and inevitable impurities. At the moment, C and Mn can enable the steel substrate to have better mechanical strength and play a better supporting role; cr, Ni, Cu, Mo and P elements can enable the steel substrate to have better corrosion resistance, and Si can enable the steel substrate to avoid surface embrittlement. And when the steel substrate is manufactured according to the proportion, the mechanical strength, the corrosion resistance and the surface embrittlement resistance can be well balanced, so that the steel substrate with better comprehensive performance and longer service life is obtained. Tests show that the annual corrosion rate of the steel substrate with the proportion in the common atmospheric environment is only 0.002mm-0.016mm, the atmospheric corrosion resistance of the steel substrate is improved by 3-8 times compared with that of a common carbon steel substrate, and the service lives of the steel substrate and a metal plate are greatly prolonged.

In some implementations, the chemical composition of the plating includes: 5 to 60 weight percent of Al, 2 to 6 weight percent of Mg, and the balance of Zn and inevitable impurities. In this case, no matter Al or Zn is dominant, the oxide film formed by Al and Mg has a higher density in the composition, and can play a better protection role.

In some implementations, the metal plate is a surface treated metal plate, the surface treatment being one or more of a passivation treatment, an oiling treatment, and a fingerprint resistance treatment. At this time, the metal plate can be prevented from generating black rust during transportation and storage, the metal can be prevented from aging during transportation and storage, and the service life of the metal plate can be further prolonged.

In some implementations, the coating has two layers, one on each of the opposing surfaces of the steel substrate. At the moment, the coating area of the coating on the surface of the steel substrate is larger, so that the two surfaces of the steel substrate can be protected, and the exposure of the steel substrate in the atmospheric environment can be further reduced to the maximum extent.

In a second aspect, the present invention provides a metal roof. The metal roof comprises at least one metal plate as described in the first aspect or in any of the implementations of the first aspect.

The advantages of the metal roof provided by the second aspect can be obtained by referring to the advantages of the metal plate described in the first aspect or any implementation manner of the first aspect, which is not further described herein.

In a third aspect, the present invention provides a BIPV system. The BIPV system comprises at least one metal plate as described in the first aspect or any implementation form of the first aspect.

The advantages of the BIPV system provided by the third aspect can be obtained by referring to the advantages of the metal plate described in the first aspect or any implementation manner of the first aspect, which is not further described herein.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic structural diagram of a metal plate according to an embodiment of the present invention.

Reference numerals:

in FIG. 1, 11-steel substrate, 12-plating.

Detailed Description

In order to facilitate clear description of technical solutions of the embodiments of the present invention, in the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

It is to be understood that the terms "exemplary" or "such as" are used herein to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" or "e.g.," is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "such as" is intended to present concepts related in a concrete fashion.

In the present invention, "at least one" means one or more, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, a and b combination, a and c combination, b and c combination, or a, b and c combination, wherein a, b and c can be single or multiple.

The realization of photovoltaic power generation on the surface of buildings is an important development direction of future buildings. In the process of applying the photovoltaic product to a building, the actual service life of the photovoltaic module is far longer than that of a metal roof made of a metal plate. The main reason for the short service life of metal roofs is that the metal coating on the surface of the metal roof is used as a sacrificial anode to protect the metal plate and is gradually consumed in the long-term use process. After the metal coating is completely consumed, the carbon steel substrate exposed in the atmosphere is corroded and perforated in a short period due to poor corrosion resistance, so that the metal component or the metal roof is structurally damaged. If photovoltaic modules are integrated on the metal roof, the service life of the whole BIPV system is greatly shortened.

In order to solve the above technical problem, an embodiment of the present invention provides a metal plate. The metal plate may be used in a building surface or in a BIPV system.

As shown in fig. 1, the metal plate includes a steel substrate 11 and a plating layer 12 provided on a surface of the steel substrate 11. The chemical composition of the steel substrate 11 includes C, Mn, P, S, Cr, Ni, Cu, Mo, and the balance of iron and inevitable impurities; the chemical composition of the plating layer 12 includes Al, Mg, and the balance of Zn and inevitable impurities.

As can be seen from the above structure, the plating layer 12 of the metal plate contains Al and Mg elements. In the atmospheric environment, the Al and Mg elements in the plating layer 12 are oxidized by themselves to form a dense oxide film after contacting with air. The dense oxide film on the surface of the plating layer 12, i.e., the surface of the metal plate, serves as a physical barrier to protect the plating layer 12 and the steel substrate 11 from corrosion. On the other hand, the steel substrate 11 of the metal plate contains elements of Cr, Ni, Cu, Mo, and P. When the plating layer 12 is consumed and the surface of the steel substrate 11 is exposed to the atmosphere, the elements Cr, Ni, Cu, Mo, and P may contact with air to undergo a chemical reaction, thereby forming a rust layer on the surface of the steel substrate 11. The rust layer has good compactness and strong adhesion with the steel substrate 11, and can prevent corrosive media in the air from contacting the steel substrate 11, so that the corrosion problem of the steel substrate 11 can be inhibited, and the service life of the steel substrate 11 is prolonged.

The embodiment of the present invention combines the above-described plated layer 12 and the steel substrate 11. In the actual use process of the metal plate, the oxidation film on the surface of the plating layer 12, the plating layer 12 as a sacrificial anode, the rust layer on the surface of the steel substrate 11 and the steel substrate are sequentially used as protective structures to play a role in resisting corrosion. Under the combined action of the multilayer protection structure, the service life of the metal plate can be greatly prolonged, so that the service life of the metal plate is longer than 30 years.

The steel substrate 11 is a main structure of a metal plate. The C and Mn in the steel substrate 11 are used as strengthening elements, which can play a role in strengthening the mechanical property of the steel substrate 11, thereby improving the pressure resistance and the service life of the steel substrate 11.

The chemical composition of the steel substrate 11 described above further includes Si. In the process of forming the plating layer 12 by dip plating the steel substrate 11, Si can inhibit the impurity element Fe in the steel substrate 11 from reacting with Al in the plating solution (plating layer 12), and avoid forming intermetallic compounds of Fe and Al. The intermetallic compound of Fe and Al is hard and brittle, and is liable to cause cracking during the forming process of the steel substrate 11, resulting in a decrease in adhesion between the plating layer 12 and the steel substrate 11. In the prior art, Si element is generally added into the plating solution, and Al-Fe-Si-Zn fine compounds are formed on the surface of the steel substrate 11, so that the Fe element in the steel substrate 11 is inhibited from being rapidly dissolved into the plating solution, and the rapid reaction of Fe and Al is inhibited. According to the embodiment of the invention, Si is added into the steel substrate 11, so that the problems that the plasticity of the plating layer 12 is reduced by the multi-element intermetallic compound when Si is added into the plating solution and the plating layer 12 is easy to crack during complex forming can be solved, the plasticity of the plating layer 12 can be improved, and the performance of the plating layer 12 can be ensured. On the other hand, the melting point of the plating solution can be prevented from rising, the energy consumption of the dip plating process can be prevented from increasing, the energy consumption of the dip plating process can be effectively controlled, and the cost can be reduced.

In practical applications, the amount of Si added to the steel substrate 11 may be determined according to the ratio of Al in the plating layer 12. Illustratively, the ratio of 100 times the mass percentage of Si in the steel substrate 11 to the mass percentage of Al in the coating layer 12 is 1.8 to 4.2. For example, the ratio of 100 times the mass percentage of Si in the steel substrate 11 to the mass percentage of Al in the plated layer 12 is 1.8, 1.9, 2, 2.5, 2.8, 2.9, 3, 3.3, 3.6, 3.8, 4, 4.1, 4.2, or the like. In this case, the amount of Si added is well matched with the amount of Al added, and the reaction of Fe and Al can be suppressed well.

Preferably, the ratio of 100 times the mass percentage of Si in the steel substrate 11 to the mass percentage of Al in the plating layer 12 is 2 to 3.5. For example, the ratio of 100 times the mass percentage of Si in the steel substrate 11 to the mass percentage of Al in the plated layer 12 is 2, 2.2, 2.4, 2.5, 2.7, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, or the like. In this case, when the amounts of Si and Al added satisfy the above ranges, the reaction of Fe with Al can be suppressed more favorably, and the adverse effect of an excessively large Si content on the steel substrate 11 can be avoided.

In practical applications, the chemical composition of the steel substrate 11 may include: 0.02 wt% -0.08 wt% of C, 0.20 wt% -1.60 wt% of Si, 0.60 wt% -1.80 wt% of Mn, 0.01 wt% -0.09 wt% of P, less than 0.025 wt% of S, 0.15 wt% -3.60 wt% of Cr, 0.15 wt% -3.60 wt% of Ni, 0.15 wt% -0.60 wt% of Cu, 0.15 wt% -0.60 wt% of Mo, and the balance of iron and inevitable impurities. At the moment, C and Mn can enable the steel substrate to have better mechanical strength and play a better supporting role; cr, Ni, Cu, Mo and P elements can enable the steel substrate to have better corrosion resistance, and Si can enable the steel substrate to avoid surface embrittlement. Moreover, when the steel substrate 11 is manufactured according to the above-mentioned proportion, the mechanical strength, the corrosion resistance and the surface embrittlement resistance can be well balanced, so that the steel substrate 11 with better comprehensive performance and longer service life can be obtained. Tests show that the annual corrosion rate of the steel substrate 11 with the proportion in the common atmospheric environment is only 0.002mm-0.016mm, the atmospheric corrosion resistance of the steel substrate is improved by 3-8 times compared with that of a common carbon steel substrate, and the service lives of the steel substrate 11 and a metal plate are greatly prolonged.

Illustratively, the mass percent of C in the steel substrate 11 may be 0.02 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.08 wt%, etc. The mass percentage of Si may be 0.20 wt%, 0.30 wt%, 0.50 wt%, 0.7 wt%, 0.90 wt%, 1.0 wt%, 1.2 wt%, 1.4 wt%, 1.6 wt%, etc. The mass percentage of Mn may be 0.60 wt%, 0.8 wt%, 1.0 wt%, 1.2 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, etc. The mass percentage of P may be 0.01 wt%, 0.02 wt%, 0.04 wt%, 0.05 wt%, 0.07 wt%, 0.09 wt%, or the like. The S may be 0.025 wt%, 0.02 wt%, 0.015 wt%, 0.010 wt%, 0.008 wt%, or the like. The mass% of Cr may be 0.15 wt%, 0.8 wt%, 1.0 wt%, 1.5 wt%, 1.8 wt%, 2.0 wt%, 2.5 wt%, 3 wt%, 3.3 wt%, 3.6 wt%, etc. The mass percentage of Ni may be 0.15 wt%, 0.7 wt%, 1.0 wt%, 1.4 wt%, 1.8 wt%, 2.0 wt%, 2.6 wt%, 3 wt%, 3.5 wt%, 3.6 wt%, etc. The mass percentage of Cu may be 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.36 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.55 wt%, 0.60 wt%, etc. The mass percentage of Mo may be 0.15 wt%, 0.2 wt%, 0.26 wt%, 0.3 wt%, 0.36 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.55 wt%, 0.60 wt%, etc.

The chemical composition of the plating layer 12 may include: 5 to 60 weight percent of Al, 2 to 6 weight percent of Mg, and the balance of Zn and inevitable impurities. In this case, no matter Al or Zn is dominant, the oxide film formed by Al and Mg has a higher density in the composition, and can play a better protection role.

Illustratively, the mass percent of Al in the plating layer 12 may be 5 wt%, 10 wt%, 13 wt%, 17 wt%, 20 wt%, 25 wt%, 28 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, etc. The mass percentage of Mg may be 2 wt%, 2.6 wt%, 3 wt%, 3.3 wt%, 3.7 wt%, 4 wt%, 4.5 wt%, 4.9 wt%, 5 wt%, 5.5 wt%, 6 wt%, etc.

As shown in fig. 1, the plating layer 12 may have two layers, one on each of the opposite surfaces of the steel substrate 11. In this case, the plating layer 12 covers a large area of the surface of the steel substrate 11, and thus both surfaces of the steel substrate 11 can be protected, and the exposure of the steel substrate 11 to the atmospheric environment can be minimized.

The metal plate composed of the steel substrate 11 and the plating layer 12 is a surface-treated metal plate. The surface treatment is one or more of passivation treatment, oiling treatment and fingerprint resistance treatment. Specifically, after the metal plate is manufactured, the metal plate is subjected to passivation treatment, antirust treatment such as antirust oil coating and fingerprint resistance treatment, so that the surface of the metal plate is optimized. At this time, the metal plate can be prevented from generating black rust during transportation and storage, the metal can be prevented from aging during transportation and storage, and the service life of the metal plate can be further prolonged.

The embodiment of the invention also provides a metal roof. The metal roof comprises at least one metal sheet as described above. Specifically, the metal roof formed by a plurality of metal plates can be applied to a factory building roof and the like. The beneficial effects of the metal roof can refer to the beneficial effects of the metal plate, and are not described again here.

The embodiment of the invention also provides a BIPV system. The BIPV system includes at least one metal plate. The beneficial effects of the BIPV system can be referred to the beneficial effects of the metal plate, and are not described herein again.

The service life of the improved metal plate is longer than 30 years, and the actual service life of the photovoltaic dual-glass assembly of the BIPV system is also longer than 30 years. At this time, the service life of the BIPV system can be ensured to be more than 30 years, so that the total power generation capacity of the BIPV system can be improved.

In order to further explain the performance of the metal plate in detail, the embodiment of the invention also provides a specific embodiment of the metal plate.

The method of manufacturing a metal plate according to any one of the first to fifth embodiments includes:

step 1: the steel billets were smelted according to the chemical composition ratios reported in table 1.

Step 2: the steel slab is subjected to hot rolling, cold rolling and other processes and then rolled into a cold-rolled steel substrate.

And step 3: and carrying out hot dipping and post-treatment on the cold-rolled steel substrate by using the metal plating solution to prepare the metal plate with the plating layer. The metal plating solution and the plating layer have the same composition, and the composition is shown in Table 2.

TABLE 1 chemical composition of steel substrate (billet) (in wt%)

Numbering	C	Si	Mn	P	S	Cr	Ni	Cu	Mo
										Example one	0.05	0.22	1.80	0.02	0.013	0.15	1.80	0.35	0.50
Example two	0.03	0.45	0.98	0.04	0.009	3.45	0.15	0.60	0.28
										EXAMPLE III	0.08	1.52	0.65	0.08	0.012	2.40	3.60	0.15	0.15
Example four	0.02	1.60	0.60	0.01	0.020	3.60	0.82	0.24	0.60
										EXAMPLE five	0.06	0.20	1.27	0.09	0.005	0.98	2.27	0.51	0.33
Comparative example 1	0.06	0.05	0.34	0.01	0.017	Is free of	Is free of	Is free of	Is free of

TABLE 2 chemical composition of plating layer (Metal plating solution) (unit of Al, Mg, Si is wt%)

Six metal sheets according to the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, the fifth embodiment and the first comparative embodiment were produced according to the above-described metal sheet production method, based on the chemical composition of the steel substrate described in table 1 and the chemical composition of the metal plating solution described in table 2.

T-bend tests were performed on six metal plates obtained in the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, the fifth embodiment and the first embodiment, and the adhesion of the plating layer was measured, and the results are shown in Table 3.

TABLE 3T-bend Performance of Metal sheets

Numbering	1T	2T	3T
				Example one	Cracking of coating	Coating is intact	Coating is intact
Example two	Cracking of coating	Coating is intact	Coating is intact
				EXAMPLE III	Cracking of coating	Finish coatingGood taste	Coating is intact
Example four	Cracking of coating	Coating is intact	Coating is intact
				EXAMPLE five	Cracking of coating	Coating is intact	Coating is intact
Comparative example 1	Coating peeling off	Coating peeling off	Cracking of coating

As is apparent from the test results of tables 1, 2, and 3, in the first, second, third, fourth, and fifth examples, the steel substrate was added with Cr, Ni, Cu, Mo, P, and Si elements, and the coating was not added with Si elements, and the produced metal sheet was cracked in the 1T coating and was good in the 2T and 3T coatings after the T bending test. The steel substrate of the comparative example I does not contain Cr, Ni, Cu, Mo and P elements, and the coating contains Si, so that after T bending test of the manufactured metal plate, the 1T coating falls off, the 2T coating falls off and the 3T coating cracks. The metal plates of the first comparative example, the second comparative example, the third comparative example, the fourth comparative example, the fifth comparative example and the first comparative example show that the plating adhesion of the metal plate manufactured by the embodiment of the invention is obviously better than that of the first comparative example.

While the invention has been described in connection with various embodiments, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a review of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

While the invention has been described in conjunction with specific features and embodiments thereof, it will be evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the invention. Accordingly, the specification and figures are merely exemplary of the invention as defined in the appended claims and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A metal plate is characterized by comprising a steel substrate and a coating layer arranged on the surface of the steel substrate;

the chemical components of the coating comprise Al, Mg, and the balance of Zn and inevitable impurities.

2. A metal sheet according to claim 1, characterised in that the chemical composition of the steel substrate also comprises Si.

3. The metal sheet according to claim 2, wherein the ratio of 100 times the mass percentage of Si in the steel substrate to the mass percentage of Al in the plating layer is 1.8 to 4.2.

4. The metal sheet according to claim 2, wherein the ratio of 100 times the mass percentage of Si in the steel substrate to the mass percentage of Al in the plating layer is 2 to 3.5.

5. A metal sheet according to any one of claims 1 to 4, wherein the chemical composition of the steel substrate comprises: 0.02 wt% -0.08 wt% of C, 0.20 wt% -1.60 wt% of Si, 0.60 wt% -1.80 wt% of Mn, 0.01 wt% -0.09 wt% of P, less than 0.025 wt% of S, 0.15 wt% -3.60 wt% of Cr, 0.15 wt% -3.60 wt% of Ni, 0.15 wt% -0.60 wt% of Cu, 0.15 wt% -0.60 wt% of Mo, and the balance of iron and inevitable impurities.

6. The metal sheet of claim 5, wherein the chemical composition of the coating comprises: 5 to 60 weight percent of Al, 2 to 6 weight percent of Mg, and the balance of Zn and inevitable impurities.

7. The metal plate according to any one of claims 1 to 4, wherein the metal plate is a surface-treated metal plate, and the surface treatment is one or more of passivation treatment, oil coating treatment and fingerprint resistance treatment.

8. A metal sheet according to any one of claims 1 to 4, wherein the coating is provided in two layers, one on each of the opposite surfaces of the steel substrate.

9. A metal roof comprising at least one metal sheet according to any one of claims 1 to 8.

10. A BIPV system comprising at least one metal sheet according to any one of claims 1 to 8.