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Solar Thermal Project

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Solar domestic hot water systems. What they are and how they save you money.

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Solar Thermal Project

  1. 1. This slide show gives you an idea of what a solar thermal system is and how it can save you money.
  2. 2.  Solar thermal is a term used to describe heat (rather than electricity) that is generated by the sun. Examples would be solar swimming pool heaters and household domestic water heaters. The focus of this presentation is solar domestic hot water systems. These systems will save you money by producing negawatts.  A negawatt is a negative megawatt: a megawatt of power saved by increasing efficiency or reducing consumption. Physicist Amory Lovins coined the term and introduced it in a speech in 1989.  Solar Domestic hot water systems have a typical 5 to 8 year return on your investment.
  3. 3. 2. Solar storage tank and heat exchanger Solar storage can be an 80 to 120 gallon tank with a built in heat exchanger designed specifically for solar storage applications or in the spirit of “reduce, reuse, recycle”. You can reuse your existing water heater with an external heat exchanger if the tank is relatively new and well insulated.
  4. 4. 3. Pump Station and differential controller. The pump station moves the heat transfer fluid (non- toxic glycol) from the solar collector and transfers the heat of the sun to your solar storage tank when the differential controller detects sufficient heat is available to be captured.
  5. 5. 4. Back-up heat source for when the sun isn’t shining. We incorporate Stiebel Eltron Tempra tankless electric whole house water heaters into our design. The advantage of an on demand water heater is you are not paying to keep water hot 24 x 7 x 365. A tankless water heater alone would save you money. Making it part of a solar thermal installation is an even better solution. When the sun is capable of heating the water to your desired temperature, the hot water simply passes through the unit without using any additional energy.
  6. 6. R & D work for the SEIDO line of evacuated tubes using heat pipe technology was carried out by the Daimler-Benz Aerospace Group, in cooperation with Beijing SUNDA Solar Energy Technology Company, based on experience gained in the temperature control of satellite electronics. The main component of a SEIDO collector is the aluminum absorber mounted in an evacuated glass tube. The absorber, coated with a special aluminum nitride layer, converts incoming solar radiation to heat. The special coating absorbs more than 92% of the arriving radiation, but radiates less than 8% back to the environment. Heat transfer from the absorber to the fluid circuit is performed by the “heat pipe”. A heat pipe is a closed system, carefully evacuated and charged with a small amount of water before it is sealed. The absorber imparts heat to this water, causing it to evaporate. The steam rises to the upper end of the heat pipe where it transfers heat to the fluid circuit via a metallic conduction bridge. Being a “dry” connection, fluid in the heating circuit does not flow through the collector. The absorber and heat pipe are mounted in a sealed evacuated glass tube, cutting heat losses via conduction and convection. The stable vacuum assures that the collector performs at low outside temperatures and protects the absorber against the environment.
  7. 7.  Modern technology with roots in aerospace industry  Works in all climates including areas with long winters  Attractive return on investment - quicker than solar PV  Modular design means you can add on as your budget allows  Easy installation and servicing  Dual uses - domestic water with space heating support or pool/spa heating
  8. 8.  Regarding Sunda Evacuated tube Collectors   Q1 Why is this a better collector than a flat plate? A1 There are various reasons: Higher yearly efficiency due to the superior insulation provided by the vacuum. This makes vacuum tube collectors much better for winter space heating applications as well as all year DHW. Easier Installation & Servicing – tubes are installed/removed individually without special tools. You don’t have to shut the system down if a tube is removed due to the dry connection to the heat exchange manifold (no leakage potential) Longer Life – absorber surfaces are protected from environmental degradation by the hermetically sealed glass tube. Tubes Rotate – at installation the tubes can be adjusted on axis to compensate for non-south-facing roofs (flat plates require building a frame to tilt the array)   Q2 How do Sunda collectors compare to and so called “double glass wall” products? A2 In Sunda evacuated tubes the absorber surface and heat pipe reside in the vacuum environment, which prevents any deterioration in long-term performance. This is not the case with the double glass wall tubes in which both absorber and heat pipe are open to ambient air. Being exposed to air, the copper to aluminum interface between absorber plate and heat pipe is subject to oxidation which may lead to degraded performance over time. Double glass wall tubes are also subject to collection of water from condensation which could freeze and break glass tubes in frost prone environments. These concerns are not applicable to the Sunda design.  
  9. 9.  Regarding Sunda Evacuated tube Collectors   Q3 Will the glass break in a hailstorm? A3 The tubes are manufactured and tested to withstand 35mm (1.38 inch) diameter hailstones. The glass is low-iron tempered glass that is 2.5mm thick.   Q4 How can you tell if you have lost the vacuum? A4 All tubes now being delivered have a silvery coating on the inside at the bottom of the tube. When vacuum is lost, this coating depletes and the tube becomes clear. Older style tubes did not have this feature and you had to rely on observing a build-up of condensation inside the tube as an indicator of vacuum loss.   Q5 How many tubes do you need and how much space is required? A5 For DHW we typically use 4 tubes per person, which assumes 20 gal/person/day usage rate and raising the water temperature from say 55 F to 120 F at a minimum. A 2-person family would need a Seido 1/5-8 tube collector and a 50 gal storage tank. A 4-person family needs a Seido 1/5-16 tube collector and an 80 gal tank. The 16-tube collector is just over 6ft wide (75.6”) and about 7 ft long (83”). Q6 Can I heat my house with these? A6 Yes, provided that the home is well insulated, thereby having a low heat loss to the environment. There are no rules of thumb for sizing a space heating array based on square footage of a house. You have to know the heat loss, design temperatures, weather data, and solar radiation available to estimate the size. It will be larger than the DHW component alone.
  10. 10.  Regarding Sunda Evacuated tube Collectors   Q7 Is there a potential of overheating? A7 Yes, any solar thermal collector can overheat if the circulator is off during peak sun hours for a long period of time. The pressure relief valve guards against damage to the system components. The tubes will not “blow-up” or break due to high temperatures.   Q8 What is the warranty? A8 Six full years unconditional on the tubes. If you lose a vacuum seal during the first six years after purchase, you receive a replacement tube free.   Q9 How heavy is the collector? A9 Only 110 lbs for the 8-tube, and 220 for the 16-tube when fully assembled.    Q10 What is the payback or ROI? A10 Half as long as PV but still on the order of 5-7 years when compared to heating with electricity. It depends on usage and cost of energy. What is the payback on a conventional water heater from the Home Depot? None – you just pay and pay and pay. What is your energy independence worth to you? It should be “priceless”.  
  11. 11.  Regarding Sunda Evacuated tube Collectors   Q11 How are they shipped? A11 Collectors are crated and shipped by common carrier. Only single replacement tubes can be shipped via UPS.   Q12 What is the life of a tube? A12 The statistical “mean life to failure” is 15 years.   Q13 Are these new? A13 No, the technology is about 20 years old. The Sunda tubes were developed in Germany by Daimler-Benz Aerospace in cooperation with Sunpu, a Chinese solar energy research company.   Q14 Why does one tube have a straight absorber and the other a bent one? A14 Seido 1 tubes have a straight absorber. These tubes can be rotated on axis to compensate for non-south- facing roofs. The Seido 5 tubes have a convex absorber providing 20% more surface area. They produce more heat per day than the Seido 1’s but cannot be turned on axis and should therefore be used only for true south-facing roofs (+/- 10 deg).   Q15 Which side of the absorber in the tubes should face to the sun? A15 Regardless of which Seido tube is used, always face the blue side to the sun. It is treated with a selective coating which absorbs the most energy from the sun’s rays as possible.
  12. 12. Contact us today! Web: http://www.controlaltenergy.com Phone: 570-754-0053 Email: ed.woll@controlaltenergy.com

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