Photovoltaic Evaporative Chimney I–V Measurement System

Pablo Casado,José M Blanes,Javier Ruiz Ramírez,Cristian Torres,Francisco Javier Aguilar Valero,Manuel Lucas Miralles

doi:10.3390/en14248198

Abstract

The photovoltaic evaporative chimney is a novel solar-cooling system that serves a double purpose: it increases the efficiency of the photovoltaic (PV) panels and it cools down a water stream which can be used to dissipate the heat from a refrigeration cycle. One of the major issues arising from the operation of the chimney is the temperature stratification in the panel due to the movement of the air in the chimney. This effect can trigger the activation of the bypass diodes of the module, creating local maximum power points (MPP) that can compromise the grid-tied inverter tracking. To fill this gap, this paper deals with the design and implementation of an I–V curve measurement system to be used in the performance analysis of the system. The I–V curve tracer consists of a capacitive load controlled by a single board computer. The final design includes protections, capacitor charging/discharging power electronics, remote commands inputs, and current, voltage, irradiance, and temperature sensors.The results show that the modules bypass diodes are not activated during the tests, and no local MPPs appear. Moreover, the curves measured show the benefits of the photovoltaic chimney: the cooling effect increases the power generated by the PV panels by around 10%.

Highlights

The 2030 climate and energy framework includes EU-wide targets and policy objectives for the period from 2021 to 2030
The cooling effect of the evaporative chimney is evident, and so is the temperature stratification with a more than 20 ◦ C difference between the lower and upper part of the PV, matching the results reported by Lucas et al [18], Figure 2
To ensure that the temperature stratification caused by the chimney does activate the bypass diodes causing local maximums, regardless of the ambient conditions, a periodic measurement of the curves was programmed, and a curve sweep was performed every one minute

Summary

Introduction

The 2030 climate and energy framework includes EU-wide targets and policy objectives for the period from 2021 to 2030. According to EU information, 40% of the total energy consumption of the Union comes from the buildings sector, and this is responsible for 36% of greenhouse gas emissions In this sense, the European Directives are focused on improving the energy efficiency of buildings to reach the ambitious goal of carbon neutrality by 2050. A buoyancy-driven flow is induced in the channel of the chimney closer to the module due to the temperature difference between the panel and the ambient air. As a result, this flow cools down the panel, increasing its performance. The system serves a double purpose: increasing the efficiency of the PV panel and cooling down a water stream which can be used to dissipate the heat from a refrigeration cycle (water–water heat pump)

Objectives

Methods

Results

Conclusion