Development Trend of BMPV and Thinking about It

I. Introduction
 With the rapid development of PV power industry around the world, BIPV has become one of the world’s most important markets of PV applications. In 2009, the Ministry of Finance and Ministry of Housing and Urban-Rural Development of the People’s Republic of China issued two documents to speed up application of solar PV technologies in buildings, namely Regulations on Accelerating Building Integrated Solar PV Applications and the Views of Implementation and Interim Measures on Financial Subsidies for Building Integrated Solar PV Applications. This specialized policy is of great importance for opening up China's PV market, and has received great attention from people of all walks of life.
 
II. A More Accurate Definition of BIPV
 1. What is BIPV?
BIPV is the acronym of Building Integrated Photovoltaics; PV is the main term, while BI is a modifier. The literal translation of it is “PV power generation system integrated into the building”. In China, BIPV often refers to “PV building” or “Building Integrated Photovoltaics”
   The conception of BIPV need to be expanded and a more accurate definition need to be made so as to put this technique into practice. It should be defined as: "PV power generation system installed on the buildings", that is "Building Mounted Photovoltaics", which can be abbreviated as BMPV.
Therefore, in the following, BMPV will be employed to replace the present frequently used term BIPV, while the latter is considered to be one form of BMPV.
BMPV includes small, medium and large-scale PV system(BAPV) installed on the existing buildings, and the PV power generation system(BIPV), which is constructed at the same time with the design, construction and installment of buildings, and perfectly combined with the buildings. The buildings involved are made up of a variety of architecture, including all kinds of civil, public and industrial buildings, so long as they can bear the weight of PV power generation systems 
In short, BMPV can be divided into two categories: BAPV and BIPV.
2. Advantages of grid-connected BMPV
   No occupation of land and less use of soil resources;
   Dispersed, safe and distributed way for power generation;
   No Need of long-distance power transmission and lower fees for power distribution;
   High efficiency and available low cost for power generation;
   Meanwhile, it needs no battery as it is connected with the grid; hence, there will be                                                                                    no trouble along with it or maintenance.
 
III. Classification of BMPV:
(1) BAPV (Building Attached Photovoltaics) refers to the PV power generation system installed on the existing buildings. PV system is installed in accordance with the form of attachment. It is designed mainly to generate power, and does not undertake any functions of buildings.
(2) BIPV (Building Integrated Photovoltaics): as one part of the external maintenance structure of the buildings, PV power generation system is designed, constructed and installed at the same time with the building. It not only has the capabilities for power generation, but also carries the function as components and materials of the buildings. It can even enhance the aesthetic feeling of the buildings, and becomes a perfect part of them.
 
IV. Forms of BMPV
BMPV are available in several forms including flat roofs, pitched roofs, sun visors, facades, glazing, etc.
(1) Flat Roofs (see illustration 1)
   From the perspective of power generation, BMPV on flat roofs has best economic benefits:
   ①Maximum electricity can be generated because it can be installed from the optimal angle ;
②Best performance can be displayed as standard PV modules can be used;
③No conflict with the function as part of the buildings;
④The cost of power generating through BMPV is the lowest.
 
(2) Pitched roofs (see illustration 2):
   BMPV on pitched roofs to the south is a better choice:
   ①Maximum or comparatively larger capacity of electricity can be generated because it can be installed from the optimal or approximately optimal angle ;
②Having good performance and lower cost as standard PV modules can be used;
③No conflict with the function as part of the buildings;
④Power generating cost is lower or lowest.
It is one of the preferred programs for installation of PV system.
Other directions (by the south) are second options.
 
(3) Sun Visors
   Sun visors consist of two kinds: tracking and non-tracking. Standard or specially-made modules can be applied into both of them. The cost is approximately the same or a little higher than that of the pitched roofs, which varies from different situations.
(4) Facades (see illustration 3)
②It must be designed, constructed and installed at the same time with the buildings. The progression of PV system is constrained by the overall progression of the building;
③PV array deviates from the optimal angle for installation, and therefore has lower output power;
④Higher cost for power generation;
    ⑤Extra “green conception” is brought to the buildings, which can increase the social value of the building and therefore become the preferred choices of building investors.
 
(5) Glazing (see illustration 4)
①Transparent modules are required, and efficiency of these modules is lower;
②Apart from the function of generating power and transparency, components of the architectural elements should conform to requirements such as mechanics, aesthetics and structural connection etc. Besides, modules may also need to be specially designed;
③Higher cost for power generation;
④Extra “green conception” is brought to the building, which can increase the social value of the building and therefore become the preferred choices of building investors.
(6) Others
Other PV systems on buildings include those on roofs of public transport stations, gas stations, sound barrier on highway, etc. The cost is similar to that of the regular roof systems.
 
5. Technical Problems Related with BIPV
(1) BAPV System
It mainly refers to the roof (flat, pitched) PV systems. In principle, it is consistent with the ground system. The key point is that the connection of PV system and the roof should not weaken the roof’s function of external structural maintenance. The layout should be designed to be harmonious with the buildings as much as possible.
Due to the low cost for power generation, it is the preferred PV building system for installers.
 
(2)BIPV System
It mainly includes the facades and glazing systems. These systems have not only special requirements for PV modules, while the design and installation should also comply with the requirements of the buildings. The requirements include the following:
①     Requirements in design:
        * Natural and harmonious;
        * Architectural and engineering design should meet the aesthetic requirements, being beautiful, elegant, and pleasant;
        * Proper coordination between colors and materials;
        * Structure size is concordant with the overall architectural layout;
        *Overall appearance of the building should match and be concordant with the PV system;
        *Innovative designing concept.
②     Technique requirements for solar cells and modules:
      Requirements for cells: the higher efficiency the better, stable performance, low cost; mainly marine color, other colors may lower the efficiency.
   Requirements for modules: strength, lifespan, size, appearance and connections meet the requirements for architectures; different architectures have special requirements in terms of transparency, heat insulation, sound insulation, fireproofing, explosion-proof etc;
   Encapsulation materials: meet different functional requests of the components: such as front and rear glass, EVA, etc.
   Structural elements: PV tiles, roof components, facades components, transparent components, and glazing components, etc.
   As the BIPV (such as the roof components, facades components and the glazing components) has special requests for the system design, component design and manufacture, system installation etc., the cost for power generation may be high. However, as it can replace the original building materials, and may save time for construction, and meanwhile the "green building" concept is added to the architectures by PV building system; therefore it can increase the social value of the building and become the PV application buildings favored by investors.
 
6. The Composition of Overseas PV Markets and Thinking about it
(1) The Composition of PV Markets in Germany
Market share of BIPV (facades and glazing that reflect the concept of PV system integration): 1%;
Market share of BAPV (PV system attached to the buildings, usually refer to the PV systems installed on existing buildings, like flat roofs and pitched roofs etc.): 89%;
Market share of ground mounted PV systems: 10%.
(2) Inspiration of PV Markets in Germany and Thinking about it
By 2008, BMPV technology in Germany accounted for 90% of the total market share, 89% of which were installed on the roof top (BAPV), while facades and glazing (BIPV) etc., which are designed and installed at the same time with the buildings, only makes up 1%. It is mainly due to the implementation of the policy of "Feed-in-tariff", which made the investors seek to get the most generating capacity at the expense of the lowest cost. Therefore, flat roofs and pitched roofs systems have become the best choice due to the factors below: they can be designed at an optimal or approximately optimal angle, standard and low-cost PV modules of good performance can be used. What’s more, the installation is simple, and it won’t make conflictions with the external building structures; so it can achieve best investment benefits, hence become the best choice for PV investors.
 
In addition, the growth rate of new architecture lags far behind PV development; therefore, existing buildings become mainly the best choice, and thereby BAPV become the major part in present PV building markets.
 
Although facades and glazing (BIPV) can be perfectly matched with the architecture by the way of designing and installing at the same time with the buildings, the performance of the modules may be lower because of the special requirements for architectural components, and what’s worse, the PV array may sometimes deviates from the optimal angle, and has lower power output, higher generation cost, as well as lower investment benefits.
 
However, the conception of “green architecture” can be delivered by BIPV, which hence increase the value of the buildings and become the preferred choice of the architectural investors. Here, costs are not to be offset by selling power, but to make huge profits by the added-value of “green concept”.
 
III .The world PV market and the development trend of BMPV
1 Current Situation: 1998-2008, PV market in world's major countries and regions
In 2008, the installed capacity is about 5600 MWp in the world
In 2008, the total installed capacity of photovoltaic power generation is 17.9GWp in the world, distribution amount is about 20.2GWp.
 
2 Development Trend－The roadmap for Mid-term development
 Europe: the new development plan of 2020(far exceeding the roadmap of early of this century)
 Low Level—PV Installation 132 GWp, generating capacity will reach 4.0%
 Middle Level—PV Installation 198 GWp, generating capacity will reach 6.0%
 High Level— PV Installation 389 GWp, generating capacity will reach 12.0%
United States: The grand objective of Obama Government in 2020: PV installed capacity reach 200GWp (far exceeding the roadmap of early of this century)
 
1. In the world’s PV market today, take Germany for example, BMPV accounts for 90％ (89% is BMPV, 1% is BIPV), the rest 10% is the ground station;
2. Along with the constant enlargement of the market, the proportion of the ground station will gradually increase. In 2010, the ground stations in world will be expected to grow to about 20%.
3. In the longer term future, for example, in 2050 and afterwards, the ground stations may exceed 50%, but BMPV is always an important PV market.
 
 
1. The development situation of China’s PV market
By the end of 2007, the cumulative installed capacity is 120MWp (20MWp was installed in 2007, accounting for 1.8% of this year’s total production);
    By the end of 2008, the cumulative installed capacity is 140MWp (20MWp was installed in 2007, accounting for 1.56% of this year’s total production);
   The installed capacity of PV systems in China and the change during 1976-2008.
 
2. Table of the cumulative share of China’s PV application markets (by the end of 2008)
 

 

Cumulative PV Installed Capacity ( By the end of 2008)
Market
Cumulative Installed Capacity(MWp)
Share(％)
Rural Electrification
48
34.3
Communications & Industry
35
25.0
PV Products
30
21.4
Grid-connected Rooftops
26.1
18.6
Power Stations in Large Deserts
0.9
0.6
Total
140
100
 
Among the above, the capacity approved to implement grid price is 1MW (Shanghai Chongming Island), the capacity already implemented grid price is 0.5MWp.
3. The market potential of BMPV technology in China.
(1)By 2008, the total building area in China is about 50 billion square meters, of which 16 billion square meters is for building area, 10 billion square meters of them is for housing; Approximately 16 billion square meters is rural residential area.
(2)The available area of urban residential roof is 1 billion square meters.
(3)The available area of rural residential roof is 4 billion square meters; The total area is 5 billion square meters.
(4)Currently, if 20% of these areas install solar arrays, they will generate the power of 100GWp.
(5)In 2010 and 2050,the available area will increase by 50％ and 100% respectively, the efficiency of solar arrays will increase to 15% and 20% respectively from the current 10%, while the resource extent of roofs from the current 100GWp will increase to 220GW and 390GW respectively. This is a very huge market potential.
 
4 The short and long-term prediction on China’s BMPV market
 
"Golden Sun Plan": a capacity of 640MWp or even larger will be installed in 2 to 3 years with a production value of RMB 20 billion or larger, of which BMPV proportion is likely to exceed 70%.
 
According to national industrial revitalization plan, which will be issued soon, by 2020, the total installed capacity of photovoltaic power generation in China will reach 20GWp; if the roof and the ground PV systems account for 50% respectively, then the capacity generated by BMPV can reach 10GWp.
        
V. Conclusion
 
The world’s PV industry and markets will maintain sustained and rapid development;
BMPV is the world's major application markets of PV power generation;
BMPV in China is at the eve of large-scale development, which should arouse the close attention of PV industry.
 
(The author is the Deputy Director of Chinese Renewable Energy Society (CRES), the Director of PV Professional Committee of CRES, and Researcher)