Francisca Rubio

The importance of manufacturing processes and their control for the reliability of CPV systems

Highly concentrating photovoltaic systems (HCPV) based on III-V multi-junction solar cells entered the PV market recently. Since 2008, HCPV power plants operate in various countries and valuable experiences could be gained. Reliability and durability of CPV power plant components are very much impacting the overall life cycle costs of a CPV power plant. Especially the CPV module is a critical component when considering system life time and overall economics. Soitecs CPV Modules based on Concentrix{trade mark, serif} technology are designed for outstanding robustness and reliability even under harsh environmental conditions. The reliability of a CPV module depends significantly on the manufacturing processes and their control. Therefore it is important to design CPV modules for manufacturability.

Indoor characterization at production scale: 200 kWp of CPV solar simulator measurements

In order to complement ISFOC’s characterization capabilities, a Helios 3198 CPV Solar Simulator was installed in summer 2010. This Solar Simulator, based on a parabolic mirror and a high-intensity, small area Xenon flash lamp was developed by the Instituto de Energia Solar in Madrid [1] and is manufactured and distributed by Soldaduras Avanzadas [2]. This simulator is used not only for R&D purposes, but as a quality control tool for incoming modules that are to be installed in ISFOC’s CPV plants. In this paper we will discuss the results of recent measurements of close to 5000 modules, the entire production of modules corresponding to a small CPV power plant (200 kWp). We scrutinize the resultant data for signs of drift in the measurements, and analyze the light quality before and after, to check for changes in spectrum or spatial uniformity.

1.36 – Concentration Photovoltaics

Concentration photovoltaics (CPV) is one of the PV applications with highest efficiency in the field. CPV is sensitive only to direct radiation (direct normal irradiation, DNI), which is collected by optical components and concentrated onto very high-efficiency solar cells. Systems are mounted on high-accuracy dual-axis trackers for their operation in the high solar resource areas of the world. Since 2005, CPV systems are becoming commercially available and are experiencing a technological and industrial development momentum complementing the growth of the global renewable energy market. Standardization and evaluation of demonstration systems are helping to establish reliability and quality standards for the CPV industry.

Influence of ambient conditions in the power rating of CPV modules

The determination of the ideal conditions for making the measurements to power rate a CPV module is a challenge. In general, all the methods proposed are establishing a range of filters for ambient conditions, when power rating a CPV module. In this paper, the influence of different filters in the deviation of the nomimal power rated is presented for 3 different CPV technologies using two different methods to obtain the nominal power (CSTC IEC62670 draft and PVUSA). The objective is to obtain an approach of how accurate the calculations are depending on the ambient conditions filtering. The result is that, using commercially available meteorological instrumentation and simple filters, the deviation of the power rated can be smaller than 2%.

Environmental testing results over a tracker drive train

Environmental testing following the draft of the IEC62817 standard has been carried out at ISFOC using a Soitec Solar tracker drive. The objective of this work is twofold; first to assure that the tracker design can perform under varying conditions and survive under extreme conditions and secondly to test the viability and usefulness of the tests described in the standard. After some changes in the device under test (specifically, gear-box oil) the drive system produced satisfactory results, assuring its performance under operational temperatures. Therefore, this work has demonstrated that the tests described in the standard are useful for detecting early failures.

CPV hybrid system in ISFOC building, first results

PV Off-Grid systems have demonstrated to be a good solution for the electrification of remote areas [1]. A hybrid system is one kind of these systems. The principal characteristic is that it uses PV as the main generator and has a backup power supply, like a diesel generator, for instance, that is used when the CPV generation is not enough to meet demand. To study the use of CPV in these systems, ISFOC has installed a demonstration hybrid system at its headquarters. This hybrid system uses CPV technology as main generator and the utility grid as the backup generator. A group of batteries have been mounted as well to store the remaining energy from the CPV generator when nedeed. The energy flows are managed by a SMA system based on Sunny Island inverters and a Multicluster-Box (figure 1). The Load is the air-conditioning system of the building, as it has a consumption profile higher than the CPV generator and can be controlled by software [2]. The first results of this system, as well as the first chances of improvement, as the need of a bigger CPV generator and a better management of the energy stored in the batteries, are presented in this paper.

High Resolution Direct Normal Irradiance Data for Testing CPV Plants: ISFOC Database

Knowledge about hourly solar radiation in terms of intensity and time distribution is essential for the design of solar energy systems. Accurate forecasting of solar radiation over a limited area is needed in order to estimate the available energy as a source of electricity. The increasing interest in Concentrated‐Photovoltaic Energy (CPV) as an incipient solar renewable energy demands high quality measurements of Direct Normal Irradiance (DNI). The probabilistic properties of the hourly DNI are analyzed over one‐year database once the data estimated by analytical models and compared with observations. Diffuse Fraction correlation index, Kd, derived from clearness index, Kt, appears as a tool for predicting hourly DNI from hourly Global Irradiance. A correct interpretation of DNI variations in time is presented in this work as an indispensable previous step for short‐range forecasting of the solar energy available for CPV power plants in order to assess the concentrated solar module‐tracking systems perfo...