Nicola Pearsall

Statistical investigation of the optimal averaging time for solar irradiance on horizontal and vertical surfaces in the UK

As output from photovoltaic (PV) panels is closely related to sunlight levels, monitoring solar irradiance levels is crucial for system design and predictive purposes. With advances in PV technology, urban sites at northerly locations, where both horizontal and vertical solar irradiance make significant contributions, are becoming increasingly important. The aim of this paper is to compare solar irradiance for horizontal and vertical orientations and to assess the relative effectiveness of differing averages, from 10 min to 1 h, for use in short-term prediction of solar irradiance levels for a UK site. Vertical and horizontal solar irradiance observations were collected from a monitoring station on the roof of a five-storey building at an urban site in Newcastle-upon-Tyne, UK (latitude 55°N). 10-min data was collected for 13- or 15-day periods in two summers (1994, 1995) and two winters (1993, 1994). Although mean levels for horizontal and vertical irradiance were different, as expected, general patterns were very similar indicating the possibility of predicting vertical irradiance from horizontal at the same location. 10-min, 20-min, 30-min and 1-h averaging times were compared utilising autocorrelation coefficients and ARIMA models to assess the information lost when using longer averaging intervals. For consideration of short-term changes, 10-min averages were most informative whilst hourly averages were substantially poorer.

The potential of thermophotovoltaic heat recovery for the glass industry

This paper aims to provide an overview of heat recovery by thermophotovoltaics (TPV) from industrial high‐temperature processes and uses the glass industry in the UK as an example. The work is part of a study of potential industrial applications of TPV in the UK being carried out by the Northumbria Photovoltaics Applications Centre. The paper reviews the relevant facts about TPV technology and the glass industry and identifies locations of use for TPV. These are assessed in terms of glass sector, furnace type, process temperature, impact on the existing process, power scale and development effort of TPV. Knowledge of these factors should contribute to the design of an optimum TPV system. The paper estimates possible energy savings and reductions of CO2 emissions using TPV in the glass industry.

Installation and operation of the first city centre PV monitoring station in the United Kingdom

Recent interest in the application of PV in buildings throughout northern Europe has developed a need for long-term records of the solar resource in urban situations. Previous records have usually been collected from locations quite remote from city centre sites and, furthermore, at hourly sampling frequencies which are not rapid enough for photovoltaic applications. The installation of a photovoltaic monitoring station in a city centre in the north-east of England is described. Weather monitoring instruments were installed to measure ambient temperature, wind speed and direction, relative humidity and solar irradiance. Four types of photovoltaic modules are mounted on the rig in typical building orientations in order to assess their performance with respect to PV cladding applications. Preliminary investigations have shown that the electricity generated by PV cladding on vertical surfaces experiences much less seasonal variation than that on a horizontal surface. The performance of north and south facing modules has also been compared and this has shown that the north facing modules generate reasonably large amounts of electricity, particularly during the summer months. The proportion of diffuse irradiance on a north facing surface has been studied and quantified for various amounts of global horizontal irradiance. Analysis of the cadmium telluride modules has confirmed a better response to diffuse irradiance than the silicon modules and records of the amorphous silicon module show no evidence of cell degradation.

The potential of thermophotovoltaic heat recovery for the UK industry

SYNOPSIS Thermophotovoltaics (TPV) is the use of the photovoltaic effect to generate electricity from a high-temperature thermal source. This paper aims to provide an overview of heat recovery by TPV from industrial high-temperature processes. The paper reviews the relevant facts about TPV technology and the high-temperature industry and identifies three principle locations for TPV heat recovery. For each location, one example process is assessed in terms of applicability of TPV, impact on the existing process and power scale. Knowledge of these factors should contribute to the design of an optimum TPV system. The paper estimates the range of possible energy savings and reductions of CO, emissions using TPV in the high-temperature industry.

Stochastic modelling of solar irradiance on horizontal and vertical planes at a northerly location

Sunshine levels incident in the plane of a photovoltaic panel are the overriding influence on electrical output, and modelling solar irradiance is therefore an essential step in the design and performance prediction of solar energy conversion systems. This study aims to assess the efficacy of SARIMA models and their potential for short-term prediction at a northerly latitude. Data was collected from a monitoring site on the roof of a 5-storey building at a city centre location in Newcastle upon Tyne, UK (latitude 55°N). Hourly and ten minute data relating to 13 and 15 day periods in two winters (1993, 1994) and two summers (1994, 1995) were utilised. Univariate stochastic modelling, using SARIMA models, is carried out for horizontal and south facing vertical solar irradiance. Results showed that these models provided a good fit for the ten minute averaged horizontal and vertical irradiance, with, on average, 82% and 85% of total variation being accounted for respectively. Use of hourly averaged data in these models gave a substantial reduction in the fit. Models for the winter data were a poorer fit than for summer for both orientations. It is concluded that the SARIMA approach can be used to develop prediction methods and to study rapid and large changes in PV output from extensive areas of solar cladding.

A solar cell stacked slot-loaded suspended microstrip patch antenna with multiband resonance characteristics for WLAN and WiMAX systems

In this paper, a novel self-complementary shaped multiple- L slot loaded suspended microstrip patch antenna stacked with a polycrystalline silicon (poly-Si) solar cell is presented for 2.4/5.2 GHz band WLAN and 2.5/3.3/5.8 GHz band WiMAX networks. While the proposed self-complementary shaped multiple-L slot loaded suspended patch enables the propagation of multiple TMmn modes to be present, the poly-Si solar cell works as an RF parasitic patch element in addition to its photovoltaic function. The proposed stacked solar antenna combination topology enables the radiating patch to be easily modified by slot-loading to achieve multiband resonance characteristics and the poly-Si solar cell to operate without being shaded by any RF components of the antenna ensuring an optimum solar operation performance.

A meshed multiband solar patch array antenna

In this paper, a meshed multiband solar patch array antenna, consisting of a polycrystalline silicon solar panel working as a ground plane whilst generating a DC power output of 1.48 W as a result of the photovoltaic effect with a measured solar efficiency of 14.95%, is proposed for GSM 900/1800/1900, UMTS 1900, 3.5 GHz band WiMAX and C-band applications. The proposed solar patch array antenna introduces a further potential of solar cells to be effectively used as embedded elements within communication systems, raising the awareness of solar energy and offering a practical solution to the requirement for the incorporation of solar cells/panels with microwave antennas within solar powered autonomous communication systems suffering from increasing dimensions due to the separate involvement of solar panels and microwave antennas.

A solar parabolic reflector antenna design for digital satellite communication systems

This paper introduces a compact solar parabolic reflector antenna design, with an effective DC solar performance and high gain / pencil beam antenna radiation characteristics, as an alternative to the standalone use of home-based autonomous solar panels and digital satellite antennas. The proposed solar reflector antenna consists of 2 parabolic shaped silicon solar panels with a diameter of 60 cm, each constructed by connecting individual silicon solar cells electrically in appropriate angles in order to create an approximate parabolic surface. The solar panels within the design have been connected in parallel in order to increase the total DC output level for medium and high current appliances. The bottom DC contact layer of the first silicon solar panel, which collects the DC current generated by the electrically connected solar cells within the panel as a result of the photovoltaic effect, also works as a parabolic reflector antenna with an average gain of 32.8 dB at the digital satellite downlink frequency band of 10.70 - 12.75 GHz, allocated by the ITU to the Region 1, including Europe.

The design and performance of photovoltaic façades in the UK

The integration of photovoltaics into facade systems provides the opportunity for a distinctive, visual character as well as contributing electricity to the building needs. This paper will discuss some design and performance issues, using three systems in the UK as examples. These include crystalline and thin film technologies and both inclined and vertical facade profiles.

Radiation and flight testing of ITO/InP solar cells

Several studies have demonstrated that indium-phosphide-based cells have a strong potential for space applications, due to their radiation resistance. Proton irradiation studies on ITO/InP cells in the 2-50 MeV range are summarized, and the results are compared with data for silicon and gallium arsenide cells. Emphasis is placed on flight data for ITO/InP cells from the LIPS III flight experiment. Data are presented for a period of almost two and a half years in orbit and compared to data for silicon cells on the same experimental panel. The ITO/InP cells show interesting variations in short-circuit current, which are also observed for silicon cells on the same panel and are clearly the result of some external influence. Major temperature errors have been discounted since. in this case, a large variation in open-circuit voltage would be expected, and this was not observed. Despite these variations, the data for the entire period so far received agree well with the base values calculated from the data for the first 100 days of the experiment. Thus, there is no evidence of current degradation in the ITO/InP cells to date. The silicon cells, by contrast. show a clear degradation over the course of the mission.<<ETX>>