Dispelling the Solar Myth - Evacuated Tube versus Flat Plate Panels. W illiam Comerford Sales Manager Ireland Kingspan Renewables Ltd.

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1 Dispelling the Solar Myth - Evacuated Tube versus Flat Plate Panels W illiam Comerford Sales Manager Ireland Kingspan Renewables Ltd. 1

2 The Kingspan Group Energy independent buildings for a sustainable future

3 Kingspan Renewables Product Areas Kingspan Renewables Division Kingspan Solar Kingspan HWS Kingspan Heat Pumps Kingspan Climate

4 What is Solar Energy Solar energy is radiant energy produced by the sun from a process called nuclear fusion The energy from the sun acting on the earth s surface, over a 15 minute period, is more then the earth s total energy requirement for a year. The amount of yearly global radiation on a horizontal surface may reach over 2,200 kwh/m2 in sunny regions. In Northern Europe, the values are 943kWh/m2 in London and 990 kwh/m2 in Rosslare, Ireland. The supply of solar radiation in UK and Ireland differs by a factor of 10 between summer and winter, e.g. Rosslare: 6.36 kwh/m2/day in June; 0.64 kwh/m2/day in December

5 What is Solar Energy Global radiation comprises direct and diffuse radiation. As sunlight passes through the atmosphere, some of it is absorbed, reflected and scattered by air molecules, clouds and dust particles, this is known as diffuse radiation. The portion of radiation that hits the earth s surface without any change in direction is known as direct radiation. In Ireland and UK, diffused radiation makes up between 40% (May) to 80% (December) of the total solar energy available in a year.

6 Why Use Solar Energy? Solar energy enjoys many environmental and economic advantages over other forms of energy currently used. These include: Environmentally Friendly Non-polluting: Solar hot water generation produces no emissions Non-consumptive: The suns radiation is a limitless resource Going Green for commercial projects has now become a PR advantage Economically Beneficial Cost effective: Free energy source Immediate and permanent savings Technological advancements: Improvement in solar technologies offer reduced costs and greater efficiency The amount of Co2 emissions produced to generate the equivalent of 1,836 kwh: 0, Natural Gas:180g/kWh, Oil: 238g/kWh, Electricity 459g/kWh So

7 W hy Use Solar Energy?

8 What Factors Effect a Solar Thermal System? Orientation (azimuth) collector 50% Slope (Inclination) Collector Area Storage Volume DHW Demand The difference between a collector facing south and a facing west = circa 20%, a collector facing north produces less energy A collector mounted at 90º will collect 20% less energy then a collector at an angle of 35º The larger the area the more solar energy available to be collected. Care should be taken not to oversize the system The larger the cylinder volume, the larger the thermal store The larger the demand the higher the solar energy consumption

9 What Factors Effect A Solar Thermal System? Is solar a viable energy source in UK and Ireland? YES! Ireland s daily solar irradiation is circa 3 kwh/m2 Equivalent to approx 130 litres of oil per m2 per year Zone Average solar radiation on collector surface (kwh/ M²day to to to 5.4

10 The Hard Facts Domestic Hot Water (DHW) = Approx 21% of our Domestic Energy Consumption As building standards improve and space heating demands reduce, DHW demand will not change

11 Collector Types There are 2 main types of solar collectors Flat Plate (Left) Vacuum Tube (Right)

12 Collector Types - Flat Panel Collectors Riser System Serpentine System

13 Collector Types - Flat Panel Collectors What is the effect of cold weather, wind and rain on a Flat Panel Collector? Hot Surface Cold Surface Conduction & Convection Losses Cold Weather, Wind & Rain has an ADVERSE effect on performance on a Flat Plate collector Gas Significant Thermal Losses to The Environment

14 Collector Types Evacuated Tube Collectors

15 Collector Types Evacuated Tube Collectors Hot Surface Cold Surface Radiation Losses Minimal Thermal Losses to The Environment via Thermal Losses : Cold Weather, Wind & Rain DOES NOT effect performance on a vacuum tube collector Evacuated Tube Collector: Pressure < 1 x 10-6 mbar To Provide Thermal Insulation Vacuum is THE best insulator available - Minimises Thermal Losses

16 Collector Types Advantages/Disadvantages Vacuum Tubes Advantages Higher solar yield than flat plate collectors with the same absorber area. 30% more effective Little thermal loss (only through some radiation) As the tube is sealed, dirt or moisture cannot get into the collector Works in cold, windy and humid conditions Individual tubes can be rotated to optimise ideal orientation High temperatures can be achieved Some people like the aesthetics of tubes Disadvantages Cost! Not easily integrated into the fabric of the building (e.g. roof or facade integrated) Some people do not like the aesthetics of the tubes

17 Collector Types Advantages/Disadvantages Flat Plates Advantages Lower cost Can be more easily integrated with the fabric of the building (roof integrated / facade integrated) Disadvantages Lower performance through conduction, convection and radiation therefore you need more surface area of collector Higher wind load requirements (they act like a sail and catch the wind) Glass and absorber can get dirty and effect performance Needs more maintenance Higher volume content equated to larger component sizes. i.e. expansion vessel Isn't as efficient in lower light

18 Product Selection Most applications operate at tm-ta = 50degC

19 Basic Tube Design

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21 Vacuum Tubes Durability Always look for the Hail Impact Test Report EN12975 The test is to fire a 25mm ice ball at 50mph at the tubes to ensure durability

22 System Simulation Comparisons 2m2 Evacuated Tube System

23 System Simulation Comparisons 2m2 Flat Plate Panel System

24 Stagnation The occurrence of stagnation in a solar system should be avoided. Continuous temperatures in excess of 170 C will cause the degrading of the Tyfocor solar solution and degrade its inhibitor properties, this is evident by the solution turning a brown colour (see solution on left in picture below). The solution on the right is the delivered state of the Tyfocor solution, the beaker on the left contains a solution that has been in stagnation for long periods above 170 C. The solution should be tested annually using a refractometer and ph test paper. Stagnation in a solar system can be caused by a number of reasons such as: Oversized systems correct sizing methods have been addressed in previous chapters Undersized expansion vessel correct sizing methods have been addressed in previous chapters Air locks or leaks in the system Prolonged periods of low hot water demand.

25 Commercial Solar Applications

26 System Solutions Swimming Pools One of the best applications for solar thermal due to low demand temps. High solar fractions achievable on pools in Ireland circa 65-70%

27 Large System Solutions

28 Large System Solutions

29 Process Applications

30 System Solutions Hospitals

31 System Solutions Tourism & Agriculture

32 System Solutions Alternative Uses

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