1 Department of Mechanical Engineering, Shahrood University of Technology, Shahrood, Iran

2 Iranian Institute R&D in Chemical Industries (ACECR), Karaj, Iran

3 Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran


One of the subjects in solar water heater design is considering distribution of hot water consumption during the day. For example, each of the household, commercial, office, school, and industrial consumptions have a particular distribution of hot water consumption named pattern in this article. In solar computation principles, the effect of longitude, latitude, and altitude on collector angle has been clearly presented. However, the effect of consumption pattern especially on the collector orientation has been rarely investigated. The aim of the current study is to survey the effect of various consumption patterns on the collector’s orientation and tilt angle and so calculation of related energy saving. So, five common patterns including office building, commercial building, afternoon and morning shift high school and a 15-unit apartment have been studied and optimal surface azimuth angle and tilt angle determined. It has been observed that 11 to 14 % energy saving can be archived by selecting the optimal angles with respect to hot water consumption pattern in comparison to a state that collectors are orientated for maximum reception of solar energy. Also effect of solar fraction, storage volume and amount of hot water consumption are studied and discussed.


  1. Rodriguez-Hidalgo, M.C., Rodriguez-Aumente, P.A., Lecuona, A., Legrand, M., and Ventas, R., “Domestic hot water consumption vs. solar thermal energy storage: The optimum size of the storage tank”, Applied Energy, Vol. 97, (2012), 897-906.
  2. CEN, EN 12977-2. “Thermal-solar systems and component: custom-built systems, test methods”, Brussels:(2001).
  3. Jordan, U., and Vajen, K., “Realistic domestic hot water profile in different time scales”, IEA SHC Task, 26(2001) Solar Combisystems.
  4. Spur, R., Fiala, D., Nevrala, D., and Probert, D., “Influence of the domestic hot-water daily draw-off profile on the performance of a hot-water store”,  Applied Energy, Vol. 83, (2006), 749-773.
  5. Shariah, A.M., and Lof, G.O.G., “The optimization of tank-volume-to-collector-area ratio for a thermosyphone solar water heater”, Renewable Energy, Vol. 7, (1996), 289-300.
  6. Krause, M., Vajen, K., Wiese, F., and Ackermann, H., “Investigations on optimizing large solar thermal storage tanks”, Solar Energy, Vol. 50, (2002), 155-166.
  7. Loomans, M., and Visser, H., “Application of the genetic algorithm for optimization of large solar hot water system”, Solar Energy, Vol. 72, (2002), 427-439.
  8. Kalogirou, S.A., “Optimization of solar systems using artificial neural-networks and genetic algorithms”, Applied Energy, Vol. 77, (2004), 383-405.
  9. Hobbi, A., and Sidiqui, K., “Optimal design of a forced circulation solar water heating system for a residual unit in cold climate using TRNSYS”, Solar Energy, Vol. 83, (2009), 700-714.
  10. Michelson, E., “Multivariate optimization of a solar water heating system using the Simplex method”, Solar Energy, Vol. 29, (1982), 89-99.
  11. Matrawy, K.K., and Farkas, I., “New technique for short term storage sizing”, Renewable Energy, Vol. 11, (1997), 129-141.
  12. Chang, K.K., and Minardi, A., “An optimization formulation for solar heating systems”, Solar Energy, Vol. 24, (1980), 99-103.
  13. Hawlader, M.N.A., Ng, K.C., Chadratilleke, T.T., Sharma, D., and Kelvin Koay, H.L., “Economic evaluation of a solar water heating system”, Energy Conversion and Management, Vol. 27, (1987), 197-204.
  14. Kulkarni, G.N., Kedare, A.B., and Bandyyopadhyay, S., “Determination of design space and optimization of solar water heating systems”, Solar Energy, Vol. 81, (2007), 958-968.
  15. Kulkarni, G.N., Kedare, A.B., and Bandyyopadhyay, S., “Optimization of solar water heating system through water replenishment”, Energy Conversion and Management, Vol. 50, (2009), 837-846.
  16. Kim, Y.D., Thu, K., Bhatia, H.K., Bhatia, S.C., and Ng, K.C., “Thermal analysis and performance of a solar hot water plant with economic evaluation”, Solar Energy, Vol. 86, (2012), 1378-1395.
  17. Dagdougui, H., Ouammi, A., Robba, M., and Sacile, R., “Thermal analysis and performance optimization of a solar water heater flat plate collector: Application to Tetouan (Morocco)”, Renewable and Sustainable Energy Reviews, Vol. 15, (2011), 630-638.
  18. Lima, J.B.A., Prado, R.T.A., and Taborianski, V.M., “Optimization of tank and flat-plate collector of solar water heating system for single-family households to assure economic efficiency through the TRNSYS program”, Renewable Energy, Vol. 31, (2006), 581-1595.
  19. Hussein, H.M.S., “Optimization of a natural circulation two phase closed thermosyphon flat plate solar water heater”, Energy Conversion and Management, Vol. 44, (2003), 2341-2352.
  20. Stanciu, C., and Stanciu, D., “Optimum tilt angle for flat plate collectors all over the World – A declination dependence formula and comparisons of three solar radiation models”, Energy Conversion and Management, Vol. 81, (2014) 133-143.
  21. Tiris, M., and Tiris, C., “Optimum collector slope and model evaluation: Case study for Gebze, Turkey”, Energy Conversion and Management, Vol. 39, (1998) 167-172.
  22. Skeiker, K., “Optimum tilt angle and orientation for solar collectors in Syria”, Energy Conversion and Management, Vol. 50, (2009), 2439-2448.
  23. Gunerhan, H., and Hepbasli, A., “Determination of the optimum tilt angle of solar collectors for building applications”, Building and Environment, Vol. 42, (2007), 779-783.
  24. Yakup, M.A.M., and Malik, A.Q., “Optimum tilt angle and orientation for solar collector in Brunei Darussalam”, Renewable Energy, Vol. 24, (2001), 223-234.
  25. Saraf, G.R., and Hamad, F.A.W., “Optimum tilt angle for a flat plate solar collector”, Energy Conversion and Management , Vol. 28, (1988), 185-191.
  26. Duffie, J.A., and Beckman, W.A., “Solar Engineering of Thermal Processes”, New York, John Wiley & Sons, (1991).
  27. Liu, B.Y.H., and Jordan, R.C., “A rational procedure for predicting the long-term average performance of flat-plate solar-energy collectors”, Solar Energy, Vol. 7, (1963), 53-74.
  28. Hay, J.E., and Davies, J.A., “Calculation of the solar radiation incident on an inclined surface”, In First Canadian Solar Radiation Data Workshop, (1980), 59-72.
  29. Reindl, D.T., Beckman, W.E., and Duffie, J.A., “Evaluation of hourly tilted surface radiation models”, Solar Energy, Vol. 45, (1990) 9-17.
  30. Klucher, T.M., “Evaluation of models to predict insolation on tilted surfaces”, Solar Energy, Vol. 23, (1979), 111-114.
  31. Perez, R., Stewart, R., Seals, R., and Guertin, T., “The development and verification of the Perez Diffuse Radiation Model”, Sandia National Laboratories Contractor Report #SAND88-7030, (1988) 150.
  32. Kalogirou, S., “Solar Energy Engineering: Processes and Systems”, Elsevier Inc., (2009).
  33. Moghadam, H., Tabrizi, F.F., and Sharak, Z.A., “Optimization of flat pale collector inclination”, Desalination, Vol.  256, (2011), 107-111.