The long road to universal electrification:A critical look at present pathways and challenges

Nearly 840 million people still lack access to electricity, while over a billion more have an unreliable electricity connection. In this article, the three different electrification pathways-grid extension, centralized microgrids, and standalone solar-based solutions, such as pico-solar and solar home systems (SHS)-are critically examined while understanding their relative merits and demerits. Grid extension can provide broad scale access at low levelized costs but requires a certain electricity demand threshold and population density to justify investments. To a lesser extent, centralized (off-grid) microgrids also require a minimum demand threshold and knowledge of the electricity demand. Solar-based solutions are the main focus in terms of off-grid electrification in this article, given the equatorial/tropical latitudes of the un(der-)electrified regions. In recent times, decentralized solar-based off-grid solutions, such as pico-solar and SHS, have shown the highest adoption rates and promising impetus with respect to basic lighting and electricity for powering small appliances. However, the burning question is-from lighting a million to empowering a billion-can solar home systems get us there?The two main roadblocks for SHS are discussed, and the requirements from the ideal electrification pathway are introduced. A bottom-up, interconnected SHS-based electrification pathway is proposed as the missing link among the present electrification pathways.Management SupportDC systems, Energy conversion & StorageElectrical Sustainable Energ

Electrical power consumption load profiles for households with DC appliances related to Multi-tier framework for household electricity access

Mat files (MATLAB) for electrical load profiles for various usage groups (Tiers) in off-grid electrification contexts. This is based on the Multi-tier Framework (MTF) for household electricity access. The appliances considered are the so-called super-efficient DC appliances. The load profiles are stochastic in nature. These load profiles can be used for system sizing of (renewable) energy systems that can cater to these loads. There are 5 mat files in the dataset: each one corresponds to a tier of the MTF

Open–Access Model of a PV–BESS System: Quantifying Power and Energy Exchange for Peak Shaving and Self Consumption Applications

Energy storage is vital for a future where energy generation transitions from a fossil fuels-based one to an energy system that relies heavily on clean energy sources such as photovoltaic (PV) solar energy. To foster this transition, engineers and practitioners must have open-access models of PV systems coupled with battery storage systems (BESS). These models are fundamental to quantifying their economic and technical merits during the design phase. This paper contributes in this direction by carefully describing a model that accurately represents the power directions and energy dealings between the PV modules, the battery pack, and the loads. Moreover, the general model can be implemented using two different PV generation methods, the Gaussian model and the meteorological data-based model (MDB). We found that the MDB model is more appropriate for short-term analysis compared to the Gaussian model, while for long-term studies, the Gaussian model is closer to measured data. Moreover, the proposed model can reproduce two different energy management strategies: peak shaving and maximizing self-consumption, allowing them to be used during PV--BESS sizing stages. Furthermore, the results obtained by the simulation are closed when compared to a real grid-tied PV--BESS, demonstrating the model's validity.Universidad de Costa Rica/[322-C1-467]/UCR/Costa RicaUCR::Vicerrectoría de Docencia::Ingeniería::Facultad de Ingeniería::Escuela de Ingeniería Eléctric

Testing a PV-battery Integrated Module Prototype

The fluctuating nature of solar power generation makes the coupling of energy storage and solar energy inevitable. This paper explores the integration of all the typical components of a PV-battery system in one single module, introducing a prototype of the so-called PV-Battery Integrated Module (PBIM). The electrical and thermal performance of the prototype were studied in order to analyse its behaviour under severe testing conditions. The prototype exhibited an appropriate charging efficiency of 95.7% on average, while the battery pack operated safely (at less than 45°C). When compared to a conventional system (battery and charge controller in a separated manner), the mean solar panel temperature of the prototype was 9.34% higher. However, in terms of power, the thermal losses in the PBIM resulted in an average increase of just 1.3 W (4.6%) in comparison to a conventional system. The testing validated the applicability of the integrated concept in harsh conditions, providing valuable information for future design improvements.UCR::Vicerrectoría de Docencia::Ingeniería::Facultad de Ingeniería::Escuela de Ingeniería Eléctric

Energy Management System for the Photovoltaic Battery Integrated Module

Given the complementary nature of photovoltaic (PV) generation and energy storage, the combination of a solar panel and a battery pack in one single device is proposed. To realize this concept, the PV Battery-Integrated Module (PBIM), it is fundamental to analyze the system architecture and energy management. This paper focuses on selecting a suitable architecture among the different options, while also indicating the control strategy that the converters must follow to ensure appropriate performance. Also, several modes of operation for the complete system are introduced to implement energy management. For the selected DC architecture, two case studies, viz. off-grid and peak-shaving for a grid-tied system, were employed to characterize the response of the model demonstrating its utility to perform maximum power-point tracking, excess solar power curtailment, and battery charging and discharging. The proposed control and system architecture prove to be feasible for a PV battery-integrated device such as PBIM

PV-Battery Integrated Module as a Solution for Off-Grid Applications in the Developing World

The coupling of solar panels and energy storage is inevitable and especially pertinent in places with no access to the electricity grid. This combination must be modular, providing the opportunity to scale up the system if energy demand increases, but also easy to install and user-friendly. These requirements validate the PV-Battery Integrated Module (PBIM) as a potential solution for stand-alone applications. In this paper, we assess the performance of directly integrating a battery system at the back of a PV panel in comparison to a typical solar home system (SHS) with all the components in a separated manner. The study is carried out using data from a community in the countryside of Stung Treng (Cambodia). First, the optimum battery size and PV panel rating were determined using the loss of load probability metric. Second, the extra PV power losses in the case of (PBIM) were calculated, finding that it is 2.16% less efficient than a normal SHS due to the poorer heat dissipation induced by integrating the converter and batteries at the back of the PV panel. Third, the battery capacity faded by 1% after a year of simulation. Although when compared to a typical SHS PBIM results in slightly higher system losses, the losses are moderated and their impact is minimum when considering the expected benefits derived from using PBIM in SHS. Therefore in this paper, we validate the feasibility of PBIM as a solution for standalone systems in developing countries.UCR::Vicerrectoría de Docencia::Ingeniería::Facultad de Ingeniería::Escuela de Ingeniería Eléctric

A simple methodology for estimating battery lifetimes in Solar Home System design

Este artículo fue realizado durante mis estudios de doctorado en la Universidad Tecnológica de Delft. En ese periodo fui becado por la UCRThe proliferation of Solar Home Systems (SHS) in recent times hopes to provide an alleviating solution to the global problem of energy poverty. Battery is usually the most expensive but important part of an SHS; it is also normally the first part to fail. Estimating the battery lifetime can help make informed system design choices, and it is therefore an important exercise for an SHS designer. Battery lifetime modelling is often a complex task requiring empirical data or reliance on modelling cell level electrochemical phenomena. This paper presents a simple battery lifetime estimation method specific to the application and candidate battery choices at hand. An SHS application specific simulation is carried out for a year and the effect of microcycles on the battery activity is analyzed. The concept of active Depth-of-Discharge (DOD) is introduced. Cyclic ageing of the battery is thus quantified and relative cycle lives of 2 battery technologies are compared. A delicate trade-off is demonstrated between battery sizing and lifetime. The described methodology is also compared with an empirical model and the lifetime results are found to be within 3.85%. The methodology described in this paper can potentially help SHS designers in making quick, reasonable estimations of battery lifetimes based on the intended application and battery manufacturer's data.UCR::Vicerrectoría de Docencia::Ingeniería::Facultad de Ingeniería::Escuela de Ingeniería Eléctric

Fabrication and Evaluation of Basil Essential Oil-Loaded Halloysite Nanotubes in Chitosan Nanocomposite Film and Its Application in Food Packaging

Increasing health concerns regarding the use of plasticware have led to the development of ecofriendly biodegradable packaging film from natural polymer and food additives. In the present study, basil essential oil (BEO) loaded halloysite nanotubes (HNTs) composite films were synthesized using a solution casting method. The effects of BEO and nanotube concentration on the mechanical, physical, structural, barrier, and antioxidant properties of films were evaluated. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) demonstrated well-dispersed HNTs and BEO in tailored composite films. The addition of BEO in Chitosan (Ch) film caused darkening of the film color; furthermore, the incorporation of HNTs in varied concentrations increased opaqueness in Ch/BEO film. The Ch/BEO film, upon adding HNTs 5–30 wt%, exhibited a corresponding increase in the film thickness (0.108–0.135 mm) when compared with the Ch/BEO film alone (0.081 mm). The BEO-loaded HNTs composite films displayed reduced moisture content and characteristic barrier and UV properties. The Ch/BEO film with 15 wt% HNTs was found to have enhanced antioxidant activity. The Ch/BEO/HNTs composite also managed to prevent broccoli florets from losing weight and firmness during storage. The enhanced barrier and antioxidant qualities of the nanocomposite film suggest its potential application in the food processing and packaging sector. This is the first ever report on the fabrication of nanocomposite film using BEO and HNTs for food packaging. The low production cost and ecofriendly approach make the film acceptable for further research and commercialization thereafter

A modeling methodology to evaluate the impact of temperature on Solar Home Systems for rural electrification

Este artículo fue realizado durante mis estudios de doctorado en la Universidad Tecnológica de Delft. En ese periodo fui becado por la UCRSolar Home Systems (SHS) have recently gained prominence as the most promising solution for increasing energy access in remote, off-grid communities. However, the higher than standard testing conditions (STC) temperatures have a significant impact on the SHS components like PhotoVoltaic (PV) module and battery. A modeling methodology is described in this study for quantifying the temperature impact on SHS. For a particular location with high irradiation and temperatures and a given load profile, an SHS model was simulated, and the temperature-impact was analyzed on the performance and lifetime of the SHS components. Different PV module temperature estimation models were applied, and the corresponding dynamic PV outputs were compared. The nominal operating cell temperature (NOCT) model was found inadequate for estimating PV module temperatures under high irradiance conditions. The PV yield was found to be affected by almost 10% due to thermally induced losses. When different levels of temperature variations were considered, the battery lifetime was seen to be up to 33% less than that at 25°C. The modeling methodology presented in this paper can be used to include the thermal losses in SHS for rural electrification, which can further help accordingly in system sizing.UCR::Vicerrectoría de Docencia::Ingeniería::Facultad de Ingeniería::Escuela de Ingeniería Eléctric