Evaluation of the Thermal Performance of a Solar Heating System with Sensible Heat Storage in Water and Automatic Control

Abstract

High-Andean regions exhibit a marked mismatch between the availability of solar radiation during the day and the demand for heating at night, which calls for systems capable of storing thermal energy and managing it efficiently. This work evaluates the thermal performance of a solar heating system based on sensible thermal storage in a water tank, distribution through hydronic radiators, and automatic flow control, incorporating a conditional electric backup. The analysis considers continuous operation over seven days with a temporal resolution of 60 s, using representative profiles of solar irradiance and outdoor temperature for the Puno region. The system includes 6 m2 of solar collectors, a 150 L storage tank, and a room modeled using lumped energy balances. The objective of the control system is to maintain an indoor temperature of 21 °C during the period of highest thermal demand (18:00–23:00), prioritizing the use of stored solar energy and limiting auxiliary consumption. The results show that the system maintains the indoor temperature within the thermal comfort range (20–22 °C) during 91.36% of the evaluated nighttime period, with a root mean square error of 1.67 °C relative to the setpoint and a weekly auxiliary energy consumption of 52.18 kWh. Design implications related to storage volume, building thermal losses, and radiator heat emission capacity are discussed, providing practical criteria for the implementation of solar heating systems in high-Andean dwellings.