Guillermo Escrivá-Escrivá

Improved variable step size P&O MPPT algorithm for PV systems

Algorithms for the maximum power point tracking MPP (Maximum Power Point), seek to maximize the delivered power of a photovoltaic panel. The Perturb and Observe (P&O) algorithm is the more used due to simplicity, however it is not the most efficient due to the perturbation step is fixed, at higher the size step fastest the MPP will be reached, but there would be a high steady state error; if the size step is low there would be less steady state error, but the MPP tracking became slow. Other well know method is the algorithm of Conductance Incremental (IC), in this method the step depends of the power variation versus the voltage. The variable step for P&O is more efficient for short atmospheric variations with less oscillations in the tracking and the variable step for CI is more efficient for big atmospheric variations with a fast MPP tracking. In this paper the 2 methods are combine to reduce oscillations and for a fast tracking for big and short irradiance variations.

Quantitative assessment of hybrid systems of heating domestic water based on solar energy in andean zones of Ecuador

The domestic hot water systems (DHW) used in Ecuador work with electrical energy and liquefied petroleum gas (LPG). Nowadays, Ecuador is in a process of changing its energy matrix, which involves the elimination of LPG in the residential sector. In this context, gas cooker will be replaced by induction cookers and also the gas water heaters by electrical heaters. This will cause a significant problem: high peaks in the power demand curve in the country. This work shows a quantitative assessment of different hybrid solar systems used for DHW to mitigate the electric energy consumption and LPG, showing the economic and environmental benefits. This paper presents a simulation of a solar thermal system and a photovoltaic system, each one of them supported by an auxiliary heating system. Demand for hot water is considered for a typical family of 4 members in Ecuador. TRNSYS software was used to evaluate the behavior of the systems in a whole year, whereas an analytical method was used to contrast the results. The results suggest that the solar thermal systems are more profitable due to their greater efficiency with respect to photovoltaic systems. On the other hand, the costs of solar collectors and photovoltaic panels influence in a great way in the economic survey. In regard to the auxiliary systems, economic analysis shows that a system based on LPG is more profitable than an electrical auxiliary system because it presents a saving of 17.04 % of the total expenditure required. The study also shows the economic and environmental benefits for the user and the Ecuadorian government.