1：Experimental Design and Method Selection:

Outdoor experimental tests were conducted to assess the performance of a PV/T system using water-based MWCNT nano?uid as a heat absorption agent. The study involved varying nano?uid volume concentrations (

2：05% to 3% V) with a fixed circulation rate of 2 l/min. The experimental setup included three systems:

one with nano?uid, one with pure water, and a stand-alone PV module for comparison.

3：Sample Selection and Data Sources:

Tests were performed in Cairo, Egypt, from October 2016 to March

4：MWCNT nano?uid with specific properties (5-12 μm length, 30-50 nm outer diameter) was used, sourced from US Research Nanomaterials, Inc. Meteorological data (solar radiation, ambient temperature, wind speed, humidity) were measured. List of Experimental Equipment and Materials:

20 Equipment included photovoltaic panels (SS-10WP, mono-crystalline, 10W), DC pump (Vso-15100-85501,

5：2 l/min flow rate), thermocouples (K-type), data acquisition system (NI-USB-6210), solar power meter (TM-206), digital environmental meter, digital multi-meters, density tester (EV-02), viscometer (RM 200), thermal properties analyser (KD2 Pro), and ultrasonic water bath for nano?uid preparation. Materials included MWCNT nano?uid, water, and copper absorber plates. Experimental Procedures and Operational Workflow:

Nano?uid was prepared by grinding and ultrasonic mixing for 6 hours. Tests were conducted from 9:00 AM to 4:30 PM with 30-minute intervals. Temperature, solar radiation, electrical output (voltage, current), and other parameters were recorded. The maximum power point was determined using variable load and multi-meters.

6：Data Analysis Methods:

Data were analyzed to calculate electrical efficiency (η_elec = P_max / P_in), thermal efficiency (η_th = Q_u / P_in), and combined efficiency (η_combined = η_th + η_elec). Uncertainty analysis was performed using standard methods, with overall uncertainty less than 5%.