Field analysis of solar PV-based collective systems for rural electrification.

This article analyses the long-term performance of collective off-grid photovoltaic (PV) systems in rural areas. The use of collective PV systems for the electrification of small medium-size villages in developing countries has increased in the recent years. They are basically set up as stand-alone installations (diesel hybrid or pure PV) with no connection with other electrical grids. Their particular conditions (isolated) and usual installation places (far from commercial/industrial centers) require an autonomous and reliable technology. Different but related factors affect their performance and the energy supply; some of them are strictly technical but others depend on external issues like the solar energy resource and users’ energy and power consumption. The work presented is based on field operation of twelve collective PV installations supplying the electricity to off-grid villages located in the province of Jujuy, Argentina. Five of them have PV generators as unique power source while other seven include the support of diesel groups. Load demand evolution, energy productivity and fuel consumption are analyzed. Besides, energy generation strategies (PV/diesel) are also discussed.

On the testing of large PV arrays

This paper reports on the IES-UPM experience from 2006 to 2010 in the field of the characterization of PV arrays of commercial large PV plants installed in Spain within the framework of the profitable economic scenarios associated to feed-in tariff laws. This experience has extended to 200 MW and has provided valuable lessons to minimize uncertainty, which plays a key role in quality assurance procedures. The paper deals not only with classic I–V measurements but also with watt-metering-based procedures. Particular attention is paid to the selection of irradiance and cell temperature sensors

Experimental Model to estimate shading losses on PV arrays

This paper presents a simple mathematical model to estimateshadinglosses on PVarrays. The model is applied directly to power calculations, without the need to consider the whole current–voltage curve. This allows the model to be used with common yield estimation software. The model takes into account both the shaded fraction of the array area and the number of blocks (a group of solar cells protected by a bypass diode) affected by shade. The results of an experimental testing campaign on several shaded PVarrays to check the validity of model are also reported.

Modelling of quantum dot solar cells for concentrator PV applications

An equivalent circuit model is applied in order to describe the operation characteristics of quantum dot intermediate band solar cells (QD-IBSCs), which accounts for the recombination paths of the intermediate band (IB) through conduction band (CB), the valence band (VB) through IB, and the VB-CB transition. In this work, fitting of the measured dark J-V curves for QD-IBSCs (QD region being non-doped or direct Si-doped to n-type) and a reference GaAs p-i-n solar cell (no QDs) were carried out using this model in order to extract the diode parameters. The simulation was then performed using the extracted diode parameters to evaluate solar cell characteristics under concentration. In the case of QDSC with Si-doped (hence partially-filled) QDs, a fast recovery of the open-circuit voltage (Voc) was observed in a range of low concentration due to the IB effect. Further, at around 100X concentration, Si-doped QDSC could outperform the reference GaAs p-i-n solar cell if the current source of IB current source were sixteen times to about 10mA/cm2 compared to our present cell.

Review of the Performance of Residential PV systems in Belgium

The main objective of this paper is to review the state of the art of residential PV systems in Belgium by the analysis of the operational data of 993 installations. For that, three main questions are posed: how much energy do they produce? What level of performance is associated to their production? Which are the key parameters that most influence their quality? This work brings answers to these questions. A middling commercial PV system, optimally oriented, produces a mean annual energy of 892 kWh/kWp. As a whole, the orientation of PV generators causes energy productions to be some 6% inferior to optimally oriented PV systems. The mean performance ratio is 78% and the mean performance index is 85%. That is to say, the energy produced by a typical PV system in Belgium is 15% inferior to the energy produced by a very high quality PV system. Finally, on average, the real power of the PV modules falls 5% below its corresponding nominal power announced on the manufacturer's datasheet. Differences between real and nominal power of up to 16% have been detected.

Review of the Performance of Residential PV systems in France

The main objective of this paper is to review the state of the art of residential PV systems in France. This is done analyzing the operational data of 6868 installations. Three main questions are posed. How much energy do they produce? What level of performance is associated to their production? Which are the key parameters that most influence their quality? During the year 2010, the PV systems in France have produced a mean annual energy of 1163 kWh/kWp. As a whole, the orientation of PV generators causes energy productions to be some 7% inferior to optimally oriented PV systems. The mean Performance Ratio is 76% and the mean Performance Index is 85%. That is to say, the energy produced by a typical PV system in France is 15% inferior to the energy produced by a very high quality PV system. On average, the real power of the PV modules falls 4.9% below its corresponding nominal power announced on the manufacturer's datasheet. A brief analysis by PV modules technology has led to relevant observations about two technologies in particular. On the one hand, the PV systems equipped with heterojunction with intrinsic thin layer (HIT) modules show performances higher than average. On the other hand, the systems equipped with the copper indium (di)selenide (CIS) modules show a real power that is 16% lower than their nominal value.

R&D on crystalline silicon technology: From metallurgical silicon to the PV module

Founded by Antonio Luque in 1979 Personnel: Personnel: 6464 full full-time time staff (19 professors staff (19 professors, 44 PhD PhD researchers 28 PhD students 13 researchers, 28 PhD students, 13 administrative and maintenance staff), 19 “part time” (11 “external PhD students”, 8 master students) Objective: Objective: Contribute to the deployment of Photovoltaic Solar Electricity through R&D& Contribute to the deployment of Photovoltaic Solar Electricity through R&D&i

Soiling and other optical losses in solar-tracking PV plants in Navarra

Field data of soiling energy losses on PV plants are scarce. Furthermore, since dirt type and accumulation vary with the location characteristics (climate, surroundings, etc.), the available data on optical losses are, necessarily, site dependent. This paper presents field measurements of dirt energy losses (dust) and irradiance incidence angle losses along 2005 on a solar-tracking PV plant located south of Navarre (Spain). The paper proposes a method to calculate these losses based on the difference between irradiance measured by calibrated cells on several trackers of the PV plant and irradiance calculated from measurements by two pyranometers (one of them incorporating a shadow ring) regularly cleaned. The equivalent optical energy losses of an installation incorporating fixed horizontal modules at the same location have been calculated as well. The effect of dirt on both types of installations will accordingly be compared.

Power output fluctuations in large scale PV plants: one year observations with one second resolution and a derived analytic model

The variable nature of the irradiance can produce significant fluctuations in the power generated by large grid-connected photovoltaic (PV) plants. Experimental 1 s data were collected throughout a year from six PV plants, 18 MWp in total. Then, the dependence of short (below 10 min) power fluctuation on PV plant size has been investigated. The analysis focuses on the study of fluctuation frequency as well as the maximum fluctuation value registered. An analytic model able to describe the frequency of a given fluctuation for a certain day is proposed

From irradiance to output power fluctuations: the pv plant as a low pass filter

The power generated by large grid-connected photovoltaic (PV) plants depends greatly on the solar irradiance. This paper studies the effects of the solar irradiance variability analyzing experimental 1-s data collected throughout a year at six PV plants, totaling 18 MWp. Each PV plant was modeled as a first order filter function based on an analysis in the frequency domain of the irradiance data and the output power signals. An empiric expression which relates the filter parameters and the PV plant size has been proposed. This simple model has been successfully validated precisely determining the daily maximum output power fluctuation from incident irradiance measurements.

Heterogeneous Collaborative Sensor Network for Electrical Management of an Automated House with PV Energy

In this paper we present a heterogeneous collaborative sensor network for electrical management in the residential sector. Improving demand-side management is very important in distributed energy generation applications. Sensing and control are the foundations of the “Smart Grid” which is the future of large-scale energy management. The system presented in this paper has been developed on a self-sufficient solar house called “MagicBox” equipped with grid connection, PV generation, lead-acid batteries, controllable appliances and smart metering. Therefore, there is a large number of energy variables to be monitored that allow us to precisely manage the energy performance of the house by means of collaborative sensors. The experimental results, performed on a real house, demonstrate the feasibility of the proposed collaborative system to reduce the consumption of electrical power and to increase energy efficiency.

XPS as Characterization Tool for PV: From the Substrate to Complete III-V Multijunction Solar Cells

This contribution aims to illustrate the potential of the X-ray photoelectron spectroscopy (XPS) technique as a tool to analyze different parts of a solar cell (surface state, heterointerfaces, profile composition of ohmic contacts, etc). Here, the analysis is specifically applied to III-V multijunction solar cells used in concentrator systems. The information provided from such XPS analysis has helped to understand the physico-chemical nature of these surfaces and interfaces, and thus has guided the technological process in order to improve the solar cell performance.

Performance Analysis of 10,000 Residential PV Systems in France and Belgium

The main objective of this paper is to review the state of the art of residential PV systems in France and Belgium. This is done analyzing the operational data of 10650 PV systems (9657 located in France and 993 in Belgium). Three main questions are posed. How much energy do they produce? What level of performance is associated to their production? Which are the key parameters that most influence their quality? During the year 2010, the PV systems in France have produced a mean annual energy of 1163 kWh/kWp in France and 852 kWh/kWp in Belgium. As a whole, the orientation of PV generators causes energy productions to be some 7% inferior to optimally oriented PV systems. The mean Performance Ratio is 76% in France and 78% in Belgium, and the mean Performance Index is 85% in both countries. On average, the real power of the PV modules falls 4.9% below its corresponding nominal power announced on the manufacturer?s datasheet. A brief analysis by PV modules technology has lead to relevant observations about two technologies in particular. On the one hand, the PV systems equipped with Heterojunction with Intrinsic. Thin layer (HIT) modules show performances higher than average. On the other hand, the systems equipped with Copper Indium (di)Selenide (CIS) modules show a real power that is 16 % lower than their nominal value.

Ultra-High Efficiency, High-Concentration PV System Based On Spectral Division Between GaInP/GaInAs/Ge And BPC Silicon Cells

A novel HCPV nonimaging concentrator concept with high concentration (>500×) is presented. It uses the combination of a commercial concentration GaInP∕GaInAs∕Ge 3J cell and a concentration Back‐Point‐Contact (BPC) concentration silicon cell for efficient spectral utilization, and external confinement techniques for recovering the 3J cell′s reflection. The primary optical element (POE) is a flat Fresnel lens and the secondary optical element (SOE) is a free‐form RXI‐type concentrator with a band‐pass filter embedded it, both POE and SOE performing Köhler integration to produce light homogenization. The band‐pass filter sends the IR photons in the 900–1200 nm band to the silicon cell. Computer simulations predict that four‐terminal terminal designs could achieve ∼46% added cell efficiencies using commercial 39% 3J and 26% Si cells. A first proof‐of concept receiver prototype has been manufactured using a simpler optical architecture (with a lower concentration, ∼ 100× and lower simulated added efficiency), and experimental measurements have shown up to 39.8% 4J receiver efficiency using a 3J with peak efficiency of 36.9%

PV self-consumption optimization with storage and Active DSM for the residential sector

With the rising prices of the retail electricity and the decreasing cost of the PV technology, grid parity with commercial electricity will soon become a reality in Europe. This fact, together with less attractive PV feed-in-tariffs in the near future and incentives to promote self-consumption suggest, that new operation modes for the PV Distributed Generation should be explored; differently from the traditional approach which is only based on maximizing the exported electricity to the grid. The smart metering is experiencing a growth in Europe and the United States but the possibilities of its use are still uncertain, in our system we propose their use to manage the storage and to allow the user to know their electrical power and energy balances. The ADSM has many benefits studied previously but also it has important challenges, in this paper we can observe and ADSM implementation example where we propose a solution to these challenges. In this paper we study the effects of the Active Demand-Side Management (ADSM) and storage systems in the amount of consumed local electrical energy. It has been developed on a prototype of a self-sufficient solar house called “MagicBox” equipped with grid connection, PV generation, lead–acid batteries, controllable appliances and smart metering. We carried out simulations for long-time experiments (yearly studies) and real measures for short and mid-time experiments (daily and weekly studies). Results show the relationship between the electricity flows and the storage capacity, which is not linear and becomes an important design criterion.