Application of a costing methodology to estimate capital costs of solar thermal systems in residential portuguese context

Abstract

The concerns regarding the environmental damage require changes not only on how the energy is consumed but also how it is produced. The close relationship between energy use and the economic growth exposes the need for continuous monitoring of energy consumption, which cannot be achieved without assessing capital and operational costs from its conversion to end-use. Solar thermal systems offer few advantages over other renewable resources to meet the energy demand in the small-scale building sector. Solar-thermal technologies can play a leading role in meeting the decarbonisation targets set in Europe. The reports from the International Energy Agency (IEA) show that solar heating has the potential to cover more than 16% of the lowtemperature heat use in the energy mix. In Europe, this share might translate into 45% growth of the installed solar thermal capacity by 2020, setting a challenging target of 1.3 m2 in terms of installed area of solar collectors by 2050. The main objective of the present work is to define a costing methodology able to estimate the capital cost of solar-thermal systems according to the system size and energy requirements of a specific residential building. The costing methodology consists of the derivation of a cost expression for each component by integrating thermodynamic and cost coefficients, adjusted for this kind of technology, and also taking into account real market data. The model was validated for a reference dwelling in Lisbon, with an occupation of 4 people with an estimated energy need of 2 037 kWh/year in terms of DHW. Results of the reference scenario show that is required at least 4 m2 of solar collector and the system cost ranges from 703.2 €/m2 to 763.2 €/m2, depending on the acceptable storage tank capacity. These values represent investments costs between 2 812.6 € and 3 052.8 €, which are in agreement with the data from the solar systems market since the prices of active systems start at 2 500 € for single dwelling buildings. In conclusion, the use of solar thermal systems enables the minimization of energy costs and, in some cases, the systems are capable of covering more than 40% of the total building energy load.