Experimental and theoretical analysis of thermal solar collector systems for DHW in Northern Italy

Abstract

The aim of this work is to describe a methodology for the in situ experimental evaluation of the performance of Solar Collector systems for Domestic Hot Water production (SCDHW), which are by far the most common use of solar thermal collectors. In situ monitoring of ten SCDHW, including DHW storage and back-up heating system led to an estimate of yearly performance, which has been compared with results from simulations performed using widely spread commercial software and f- chart method. Measurements were carried out for at least 20 days for each plant, with sampling rate of ten minutes. As DHW demand was unknown, it was assumed from SC area. Results show that the solar collector’s area was systematically oversized respect to actual DHW needs, resulting in measured lower efficiency (around 30%) than calculated by commercial software. Reducing DHW needs, measurements and calculations produced closer results.