Solvärme på Utö
The guest harbor on Utö, Utö Gästhamn, is currently using electricity for heating all of the water used in the showers and taps. Because of the large amount of visitors, especially during the summer months, the hot water usage gets very high and that is also the case for the electrical bills. During the year of 2011 the cost of electricity for Utö Gästhamn reached a total of 257 500 kr. Out of these 257 500 kr approximately 142 000 kr, 55 % of the total cost, were because of the water heating.The report is the result of a cooperation with Skärgårdsstiftelsen, the Green Islands-project and Utö Gästhamn where the mutual goal is to dimension a solar energy system, to promote the sustainable development.Initially the different techniques for the solar energy system are researched. The techniques are plane solar collectors, evacuated tube collectors, pool collectors and photovoltaic cells. Also geographic conditions such as solar irradiation are investigated to determine the possible performance and success of the solar energy system. To decide which technique that would be the most suitable, the performance for each different type of solar system is compared. The most important parameters taken into consideration are the initial cost, coefficient of efficiency, estimated life-span, toughness, how service-friendly it is and the performance (kWh/m2·year). The system shown to be best suited for the conditions on Utö is the plane solar collector system with a coefficient of efficiency of 70-80 % at low over-temperatures, performance ranging from 350 to 700 kWh/m2·year, a high toughness compared to the other systems and a high possible utilization all year round.Technical calculations are made for the plane solar collector system and the solar collector area required to completely cover the hot water usage during the summer season (May-August) is 178 m2 with an energy usage of 98 300 kWh and considering an entire year the area and energy usage is 158 m2 and 139 650 kWh.From existing information about the water heaters and assumed hot water usage, three investment alternatives in different price ranges are obtained from Attemptare AB. Through an investment analysis it shows that the largest system, at 83 m2 and an investment cost of 453 500 kr, is the most profitable and can generate savings at an amount of 34 080 kr/year after the investment has been payed off which is after 13 years, calculated with an increase in electricity price of 0,10 kr/kWh·year. This saving is 24 % out of the possible saving regarding the hot water heating. Furthermore this investment would promote the sustainable development by reducing the carbon dioxide footprint with 687 kg/year. This means that both savings regarding the Utö Gästamn?s economy and the environment are made wich caters for the wishes of everyone involved in the cooperation.