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Energy Sources and Renewable Energy
water heating systems towards the new systems based on photovoltaics (Herrando & Markides, 2016, Meyeres et al., 2018). However, information on these new systems is scarce and little contrasted in our climate, so it is necessary to deepen the knowledge of this technology. In this context, this work presents the design of a prototype of a PV installation for water heating with the aim of evaluating its behavior and contributing to the scientific advance of this new use of PV technology.
2. Materials and methods
This paper presents the preliminary results obtained from an experimental facility, built ex professo, in the Hydraulic Engineering laboratory of the University of Cordoba (Cordoba, Spain) consisting of a photovoltaic unit, an experimental electronic impedance adaptation system, a sanitary hot water tank and a monitoring and control system.
The photovoltaic system has five Munchen Solar 330 monocrystalline modules, inclined 25o and oriented to the South. The photovoltaic system operates at 1650 Wp, with 230.95 V open circuit voltage and a 9.11 A short-circuit current. This system will feed a 17 Ω heating resistor of 17 Ω located inside a 300L capacity insulated tank. In order to utilize the maximum available photovoltaic power and adapt the output impedance of the PV collectors to the resistance, a MPPT electronic circuit based on a 0.001 F capacitor and a MOSFET-n IRPF 250 have been designed. Power control is performed by means of an ESP 32 circuit that permanently monitors the voltage at the terminals of the capacitor to pilot the transistor gate as well as the electrical current supplied by the PV system. A recirculating pump has been installed to measure hot water production. This pump renews the water content in the tank every night and replaces it with cold water. The night-time control of the recirculating pump as well as the monitoring of the temperatures inside the tank is also implemented by means of an ESP 32-based electronic board. WIFI and BlueTooth connection of the proposed electronics makes the entire experimental device accessible from the cloud.
3. Results and conclusions
This work presents the study of the energy costs associated with this type of facilities as well as the comparison of theoretical values with experimental ones. Results demonstrate the existence of economic advantages associated with the heating of water for sanitary use by means of photovoltaic solar energy.
4. Acknowledgment
This study has been carried out thanks to the financing of the project PVACS-UCO SOCIAL INNOVA.
5. References
Herrando M., Markides C.N. (2016). Hybrid PV and solar-thermal systems for domestic heat and power provision in the UK: Techno-economic considerations. Applied Energy, 161, pp. 512-532.
Meyers S., Schmitt B., Vajen K. (2018). Renewable process heat from solar thermal and photovoltaics: The development and application of a universal methodology to determine the more economical technology. Applied Energy, 212, pp 1537-1552.
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