Energy assessment of a compact solar wall-heating system powered by a parabolic collector

This study investigates the thermal performance of a compact solar heating system designed for semiarid climates. The system integrates a 1 m² parabolic trough collector (PTC), a 50 L stratified storage tank, and an active masonry wall. Unlike conventional systems that use flat-plate or evacuated-tube collectors, this setup leverages concentrated solar radiation to improve energy delivery efficiency. An experimental prototype was developed and tested under the climate of Errachidia, Morocco, and a dynamic TRNSYS 16 simulation model was created and validated with on-site data. The model showed good agreement, with mean discrepancies below 7% for PTC outlet temperature and 5% for indoor-air temperature. Results for the winter period (December-February) indicate that raising the mirror reflectivity from 0.60 to 0.90 improves seasonal collector efficiency from 0.41 to 0.63 and increases the useful heat output by more than 50%. Increasing the tank volume by 10 L reduced indoor temperature by 1.3 °C, while doubling the active wall surface caused a reduction of 3.5 °C. Comparative simulations across 8 Moroccan cities identified Errachidia and Marrakech as optimal sites, with peak useful heat reaching 194.3 kW in March. The study confirms that a small scale, PTC-powered wall-heating system can meet thermal comfort requirements in cold seasons without auxiliary heating. The novelty lies in the combined experimental and numerical assessment of a low-cost, compact configuration tailored for space-constrained buildings in semiarid regions.