20Th European Photovoltaic Solar Energy Conference and Exhibition

20th European Photovoltaic Solar Energy Conference and Exhibition

June 6 – June 10, 2004

Barcelona, Spain

The Multi Solar Window

Eng.AmiElazariMBA

Millennium Electric T.O.U. Ltd., P.O. Box 12346, Herzelia Industrial Zone46733Israel

Phone: 972-9-9588071 Fax: 972-9-9588075 E-mail:

Abstract:

The main objective of this project is the development and integration of new photovoltaic solar panels to deliver electric power, hot water and/or hot air for heating or adsorption cooling purposes. These panels will be further integrated in the building, as windows giving it a good, aesthetic impression together with the glass surfaces that form the panels.This solution will directly answer the need to improve the low performance of the photovoltaic BIPV panels.

In order to achieve thisobjective, listed below are the scientific and technological objectives that will be the essence of this project:

• Development of a new generation of high efficiency,cost effective solarwindowpanels, capable of producing with the same collector three different types of utilities:electricity,hot water and hot air, both usable also forair conditioning.
• Increasing the electrical efficiency of the photovoltaic cells by innovative cell cooling methods.
• Development of a CFD model to determine optimal design and flow pattern for cooling of the PV cells.
• Integration of this SOLAR WINDOW concept in a test building.
• Analysis and evaluation of their operating performance.
• Optimisation of the preliminary design of the entire solar system based on the CFD and practical test results.
• Development of an optimised automatic control system for the SOLAR WINDOWsystem with special regard to the demand of the different utilities.

Background:

The EU demand for energy has been growing at a rate of between 1%-2% a year since 1986. Internal resources are inadequate to meet this demand, as Europe is using far more energy than it can produce. Despite the considerable progress made in tapping conventional energy reserves in Europe, their levels remain low and they are expensive to extract. The energy demand of the new Member States from East Europe will doubtless track that of the Union on the long-term evolution of their energy demand. While industrial needs have been relatively stable as a result of the transition to service oriented economy, the increased demand for electricity and heat from households and the tertiary sector has more than compensated this decline.

On the other hand, security of supply on Europe’s energy market must take account of the imperative to combat climate change and pursue sustainable development. The European Union will not be able to meet the commitments given at Kyotounless significant measures are taken to reduce demand. The measures will have to be in tune with the concern to reduce dependence on imported energy supplies. According to the Intergovernmental Panel on Climate Change, since 1990 global warming has been speeding up as a result of the intensification of the anthropogenic emissions of greenhouse effect gases. Some 94% of man-made CO2 emissions are attributable to the energy sector as a whole, and fossil fuels are the prime culprits.

The biggest energy users are, in absolute terms, households and tertiary sector. Excluding personal transport, 63% of households are supplied by oil and gas. They account for approximately 1/3 of total gas consumption and 18% of oil. In the last weeks and months, the price for fossil fuels increased dramatically due to political reasons and strong import dependencies in the European Union. In addition to this, renewable sources of energy are currently unevenly and insufficiently exploited in the EC. Figure 2 illustrates the solar rate for different usages the solar rate is theannual average percentage of energy required to be supplied by the sun.

State of the Art and Innovation

Nowadays, conventional solar systems are normally constructed for the generation of only one type of energy, either thermal solar energy or electric solar energy. This leads to a few problems and disadvantages like:

• Larger installation areas needed, if there is a demand for thermal and electrical energy.
• Higher acquisition costs, because of a more panels needed and longer installation times.
• Reduced efficiency of photovoltaic systems due to high temperatures in the panels.

The current photovoltaic generators in use need to palliate the low performance that does not go usually beyond 10% or 15%, because in these types of facilities the heat is not taken advantage of in an appropriate way, leading to a loss of approximately 34% of the incident energy. The performance of these systems diminishes quickly as the temperature of the collector increases, having important losses as soon as the temperature of the cells is between 40-45°C.

The solar panels available on the market have an average production of between 120 and 150 W/m2 of maximum power for the required temperatures. As far as hot water is concerned, profitability has been more than shown. With this process, a better use of solar energy is made in the most logical way without cost, as the sun does the heating. The same happens with the hot air. If these three methods are integrated (photovoltaic energy, hot water and hot air production), there will be a significant improvement, which will be followed by economical benefits for the end users of the system.

Some companies have already developed solar collectors that produce within the same unit, photovoltaic energy and hot air, but so far, there is no collector available in the market able to generate the three types of energy at the same time with same collecting surface or at high electrical efficiencies. Millennium has a stand-alone system already developed, and 29 integrated solar units of this nature have been installed in houses with very good results in energy efficiency. However, so far none of these units has been integrated in building facades.

The photovoltaic cells diminish their performance when the operation temperature increases. If the photovoltaic cell is refrigerated by air and/or water, it makes possible to obtain appropriate temperatures for the good functioning of the photovoltaic system. In this way it seeks to take advantage of the heat that gets lost with the object of heating water and air (together with the solar radiation), which can be used as energy contribution to the home. The installation of the SOLAR WINDOWshould be done in such a way that it provides the right amount of electricity, hot water and hot air.It should be fitted with batteries for the storage of energy or feed direct to the electric grid and as it has been the practise to date for systems of photovoltaic panels.

To the actual state of the art, they do not exist, therefore,the durable surface glass must:

• effectively oppose the solar irradiation in the summer, demolishing the relative consequent heating of the building;
• maximize the collection of solar radiation in winter, exploiting this phenomenon to naturally heat the environment consequently demolishing the energy consumption of the plant;
• possession of a neutral coloration that would avoid to the occupants to perceive the colors of the external environment as unnatural and distorted, with serious reductions of the comfort visual and consequent reflex on their productivity.

The SOLAR WINDOW and its integration in the building contrarily to the systems above described introduce the following advantages:

• it allows to maximize the collection of solar radiation in whatever season of the year, storing therefore "free" energy for then redistributes it according to the specific requirements of the user;
• the surplus of produced warm water can be used for the winter heating of the environment through ceiling panels, (ceiling radiant panels with operating temperature of around 35-40°C and therefore compatible with those produced by the solar panel); this system maximizes the efficiency of the heating plant and also reduces his costs and it doesn't behave movements of air masses so that minimizes the diffusion of dusts and fine pollutants, reducing therefore the phenomena of indoor pollution. The use of such system of heating (and cooling) makes the use of Solar Window particularly useful for air conditioning of clean environments as the hospitals.
• In summer times, the system can supply cold for air conditioning of buildings, either via “pumping” out hot air or by using adsorption-cooling systems, operated with hot water coming from cooling the PV cells.

Impact on Societal Objectives:

The SOLAR WINDOW project doubtless contributes to enhance the Quality of Life, Environment and Health of European Citizens. Some 94% of man-made CO2 emissions in Europe are attributable to energy sector as a whole. In absolute terms, oil consumption on its own accounts for 50% of CO2 emissions in the European Union, natural gas for 22% and coal for 28%. In terms of consumer sectors, electricity generation and steam raising are responsible for 37%, households for 24% and service sector for 5% of CO2 emissions. Therefore, reducing fossil fuels dependence and improving energy efficiency constitutes a necessity of the European Union in terms of Quality of Life, Environment and Health for the European Citizens.

Achieving the indicative objective of solar energy share in 2010 will lead to an increase in the market for the European solar energy industry and will create a significant number of new jobs. The renewable energy sector is a significant industrial sector in Europe and one of the fastest growing ones. Predictions estimate that the increase in energy provided by renewable sources will result in the creation of over 900.000 new jobs. This increase takes into account the direct, indirect and subsidy effects on employment, and jobs displaced in conventional energy technologies. Jobs displaced as a result of supporting renewable energy are significant less than corresponding to job gains. Renewable energy technologies are in general more labour intensive than conventional energy technology, in the delivering the same amount of energy output. This creation of new jobs is an opportunity to balance the share of women in this traditionally masculine sector. The export market is also particularly important as Europe, with its traditional links with Africa, South America, India and lately South-East Asia, and is in a very favourable position.

Design study for a new generation of solar window panels.