R. T. Montilla1* and A. Abanades2

1 SONNEGEX S. L., 31, Sta. Cruz de Marcenado St., 28015 — Madrid — Spam
2 Dpto. Termotecnia, ETSII, Universidad Politecnica de Madrid, Madrid — Spain
Corresponding Author, rmontilla@icai. es

Abstract

This report draws the conclusions of an economic analysis carried out to study the viability of domestic solar cooling systems in southern Spain. Due to the reduced range of small-powered absorption chillers, a 32kW machine has been selected and analysed in three different housing typologies: apartments, terraced houses, and detached houses. The results of this analysis show, as expected, that solar cooling is not already economically acceptable for domestic use, with a payback period longer than 25 years, mainly because of the high cost of the solar field. By considering public subsidies to the installation of this component, and its complementary use to pre-heat sanitary hot water and central heating water, the payback period decreases to less than five years in the most optimistic scenario.

Keywords: solar, absorption, cooling, Spain, viability

1. Introduction

Parallel to the improvement of life conditions, air conditioning devices have become almost a basic need in houses of developed countries. The extra energy demand that cooling entails has not meant a problem while electricity has been cheap. However, linked to the evolution of fuel price, the cost of electricity has started a raising period with no upper limit. This situation forces the industry to optimize the efficiency of all the energy consumer processes.

Electric vapour compression chillers are the most commonly used in domestic applications, representing almost 95% of all the domestic cooling systems. Despite the fact that these machines have a high EER, mainly caused by a high research and development grade, their electricity demand is already significant. Regarding energetic efficiency criteria, the use of solar absorption chillers, which could obtain all the needed thermal energy from a solar collector field, could represent an important decrease of this electricity demand.

With the objective of reducing energy consumption and its consequent impact on the environment, installation of solar cooling systems has been considered and analysed from an economic point of view in southern Spain.