TECHNICAL SOLUTION
Name of solutionAutonomous Solar Collector System
Category of solution
> Solar thermal > Energy storage |
PDF version to download
Related Energy School
> Renewable energy > Thermodynamics | ||||||
Short introTechnical hot water preparation system that is based on nowadays technology and is constructed by using available components from the shop of construction materials. It is alternative of wide spread metal tank or long plastic pipe with black color paint. |
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Complexity and cost of building and operating
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Complexity of building and operating:
High Cost: High |
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Materials, skills and tools requiredSkills Woodworking, plumbing and welding. Tools > Saws for wood and metal > screwdriver according to screws > knife > spanners > welding machine Materials Materials of the system used in workshops. Solar collector > absorber – ~0.90x1.86x 0.004 m copper plate > absorber pipe –D12x1 L=1.876m 7pc. and D22x1 L=1.060m 2pc copper pipes > copper tee 22x12x22 14pc; > adapter copper D22 to screw-thread 3⁄4” M; > box from water proof plywood or painted wood; > rock-wool thermal insulation thickness 50mm; > transparent strained glass, thickness 6 mm, > rubber gasket between wood box and glass; > aluminum frame for hold glass on the wood box > screws. Accumulation tank > 200 liter metal tank with screw-thread 3⁄4 M connectors at bottom, middle and top level > Water proof thermal insulation thinness 10mm and operation temperature more than +70°C Water tank > Any volume tank with screw-thread 3⁄4 M connector at bottom level. Pipe > stainless steel bending pipe DN20 ~20m and fittings, > caoutchouc thermal insulation thinness 13mm. > Regulation and safety fittings: > valves 1⁄2” or 3⁄4” 5pc; > pressure safety valve: 1.5bar; > air vent: 1⁄2”. |
Description of the solutionSystem is designed for heating technical water and is not suitable for drinking water.
Heat source is solar radiation, that heat up solar collector. Solar collector is an absorber in cover. Absorber is plate from metal, with high thermal conductivity. Plate is painted with solar lacquer or smoked with pure carbon. Solar lacquer has 8-time higher solar radiation absorption than black paint, and solar lacquer operation temperature is more than 100°C. Heat transfer from absorber to pipe and then to water. Metal pipe is connected to absorber using welding. Absorber is capsulated in cover for heat losses reduction. Cover is mostly from wood. In front is well transpired glass. Between back of absorber and cover is rock-wool thermal insulation. Heat is accumulated in water tank. Water from accumulation tank goes to solar collector bottom, then heats up and lifts up naturally. Water warming in solar collector rise water circulation in solar circle. From top of collector water goes to middle of accumulation tank. If water from solar collector is warmer than water in accumulation tank middle - then this water lifts up in accumulation tank, if colder – then goes down. Thence natural stratification appears. Cold water tank is placed in top of the system, it creates natural pressure. Pipe and heat accumulation tank is insulated for preventing heat losses to outdoor air. Hot and cold-water mixing is done with valves at consumer side. System is designed only for summer use. Water in it could freeze in cold (below 0C) climate conditions. Thence drain valve and air vents is added to the system. Surplus pressure safety valve is added to prevent explosion and thermal deformation of the system. 
Solar collector system principle scheme
Results, learnings and errors to avoid
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Life Cycle AnalysisNo analysis has been made
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Step by step guidelines for building the solution
Step 1
Preferable to start from construction of solar collector absorber pipes. Pipes should be connected in harp connection and welded, see Fig. 2. Then connect absorber pipes to the absorber plate, welding is preferable. After it, paint absorber plate with solar lacquer or coat with carbon. Build wood box according to absorber scale: 
Fig 2: Absorber dimensions
Fig. 3: Wood box of solar collector
Step 2
Put thermal insulation in wood box. 
Fig. 4: Collector thermal insulation
Step 3
then put and fix absorber. Mount rubber gasket between wood box and glass. 
Fig. 5: rubber gasket between glass and wood box
Step 4
Clean the glass from both sides and put the glass on wood box. 
Fig. 6: Glass cover of solar collector
Fig. 7: Solar collector
Step 5
Fix glass with aluminum frame. And solar collector is done. Install accumulation tank higher than solar collector. Water tank has to be installed even higher. 
Fig. 8: Solar system component highs of installation
Step 6
Connect pipes 
Fig. 9: Pipe and fitting connection
Step 7
Install pressure safety valve and air vent 
Fig. 10: safety fittings
Step 8
Perform hydraulic test - fill system with water, let air go out and let it stay for 15 min. If no smudges and physical deformations happen, then mount thermal insulation. 
Fig. 11: Insulated solar collector system
System is done.
Enjoy warm water all summer! |
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AuthorDr.sc.ing. Andrejs Snegirjovs
Experts involvedDr.sc.ing. Andrejs Snegirjovs
Institute of Physical Energetics ContactsDr.sc.ing. Andrejs Snegirjovs
Institute of Physical Energetics Krīvu street 11, Riga, Latvija, LV-1006 dr.snegirjovs@gmail.com |
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