A technique for delineating defects in silicon

A decoration and etching technique was developed to delineate several types of defects in silicon wafers, slugs and slabs. The technique was originally developed to detect interstitial type (A) defects but it has proved highly effective in decorating all kinds of other defects. Being fast, and requiring no special equipment except an inexpensive muffle furnace and a dedicated etch bench the technique has quickly become an integral part of our characterization portfolio. We discuss below how we have used this technique and its advantages over other methods used to detect A-defects.peer-reviewe

Innovative photovoltaic cooling system

With the ever-increasing adoption of solar energy and the lack of space for PV installations, targeting maximum photovoltaic operational efficiencies has become essential. One of the key challenges faced by PV installations in warm climates is thermal management, which is caused by increasing temperatures due to PV conversion inefficiencies and limited ventilation possibilities in certain installations. Despite prior art, further improvement is still needed to provide a novel system that can offer more efficient and controllable temperature decrease of photovoltaic modules in both land and offshore installations. The present invention, termed IPCoSy, satisfies the aforementioned needs in the art by providing a novel system for cooling a solar panel assembly, including at least one photovoltaic module having a plurality of solar cells generating electrical power and a PV junction box attached to the back of the photovoltaic module. A part of this invention discloses a new type of PV module that is a modification of standard commercial modules. This new PV module incorporates a water chamber at the back of a solar cell assembly to regulate operational temperatures. Another part of this invention presents an after-market cooling system that can be fitted to existing standard PV modules to add the cooling effect. This part of the invention presents solid and flexible water tanks that can be fitted directly into a gap at the back of standard PV modules. Moreover, this invention presents details on parts that distinguish this cooling system from prior art, such as an internal stream spreader to obtain better fluid dynamics and external fittings that allow the PV module to be installed at any tilt angle without jeopardizing the cooling effect. Finally, this invention discloses different application areas of this cooling system, such as residential and industrial water heating, reverse osmosis plants and offshore photovoltaic installations, showcasing the product’s versatility, adaptability and large market suitability.peer-reviewe

Floating photovoltaics – technological issues, cost and practical implications

In space constrained countries such as Malta it is difficult to envision large scale PV farms on land due to the high cost and lack of availability of large stretches of suitable land. It is therefore natural to try to venture offshore as has happened elsewhere with wind-farms. Some of the challenges – higher communication costs, corrosive effects of the sea water, long term survivability – are the same. However sea-borne PVs have an edge when it comes to cost as their deployment would be logistically simpler than the massive wind turbines. They would also be less visible from shore and therefore less likely to be opposed on aesthetic grounds. The balance of system costs for an offshore system provides some advantages and some disadvantages when compared to a land-based system however it is believed that the overall cost could be similar to or even lower especially if special panels are developed for offshore use and since no expensive land-leasing would be involved. While most of the systems reviewed are on ponds some of the adopted solutions could also work in open sea and while challenging, other problems such as rough seas and biological fouling should be surmountable.Bajada New Energy, General Membrane, EcoGroup, Econetique, Energy Investment, JMV Vibro Blocks, Solar Engineering, Solar Solutionspeer-reviewe

Income maximisation in a Maltese household photovoltaic system by means of output and consumption simulations

The installation of photovoltaic (PV) systems in the Maltese Islands plays an important role in allowing Malta to increase its share in renewable energy to meet the set European Union targets. In the Maltese residential sector, PV systems are generally installed on rooftops of households with a south-facing orientation and a 30° inclination angle. The scope of this study is to present a methodology to maximise the income for residents from electricity generated, by comparing the output of electricity generation with the electricity consumption patterns of different household types and consequently identifying the most favourable installation configurations of these PV systems. The research was carried out by simulating the monthly electricity generation of a 3 kilowatt-peak PV system for a year, as well as the hourly electricity generation for a day in each season of the year using the PVsyst software package. A total of 21 configurations were studied by altering the orientation and inclination angles used to install the PV system. This study confirms that a south-facing PV system inclined at 30° generates the most electricity in a year. However, when compared with electricity consumption patterns of low-, medium- and high-consumption households, it is shown that a south-facing PV system inclined at 40° provides a better income for residents.peer-reviewe

Photovoltaic backside cooling using the space inside a conventional frame (IPCOSY)

Inefficiencies present in solar cells result in most of the absorbed energy beingconverted into heat,causing an increase in cell temperature,which leads to a further reduction in efficiency. Various cooling technologies can be found in the literature; however, these all come with their own challenges. In this research, we have designed a Photovoltaic (PV) panel that incorporates backside water cooling by creating a water chamber in the empty space inside the Aluminium frame. This panel was termed IPCoSy (Innovative Photovoltaic Cooling System). It was tested against a conventional cooling system that allowed water to drain when the cooling is switched off and a non-cooled control panel,and the results show that, even without any flow, a daily energy gain of about 3% is possible. When a controlled flow was introduced, gains of up to 10% were achieved. These gains can be further increased when IPCoSyis installed in ideal scenarios such as reverse osmosis plants, floating PV installations,or areas requiring water heating. Therefore, this research presents a new photovoltaic panel incorporating a water chamber designed for hot climate conditions.peer-reviewe

Full-scale design, implementation and testing of an innovative photovoltaic cooling system (IPCoSy)

The field efficiency of silicon-based solar cells is dependent on various factors including temperature. An increase in temperature results in a reduced efficiency of a magnitude dependent on the solar cell’s temperature coefficient. Furthermore, an increase in solar cell temperatures beyond levels specified by the manufacturer will result in a reduced lifetime and an increased probability of potential induced degradation and even failure. Researchers have created different cooling technologies to keep the solar cells’ operating temperatures to a minimum. However, no cooling technology in the literature is adequate for both land and offshore PV installations. A patented Innovative Photovoltaic Cooling System (IPCoSy) is presented in this paper. Previously published results have confirmed the cooling effect and feasibility using small-scale prototypes. This paper presents the design challenges and results of the full-scale implementation. The full-scale prototypes are the same size as commercially available photovoltaic modules, making them easier to integrate in the current market. Therefore, this research presents the results of testing full-scale prototypes while addressing challenges related to structural integrity and fluid dynamics. The findings of this research showed that the positive effects of this cooling technology range from more than a 9% increase in PV electrical energy yield, and thermal efficiencies of up to 56%. Finally, the outcome of this research will contribute towards the United Nations’ sustainable development goal of affordable and clean energy through direct operational efficiency improvements in PV systems, as well as the enhanced tapping of solar energy for renewable thermal energy production.peer-reviewe

The Eco-Gozo concept : from a sustainable energy perspective

The Eco Gozo 2015 Vision of the Ministry for Gozo aims at making the Island of Gozo eco-friendly, supporting a sustainable society, while improving the quality of life of citizens and reducing the Island’s carbon footprint [1]. This paper aims at addressing the Eco-Gozo Concept from a sustainable energy point of view. Gozo, being a small island that fully depends on the main Island of Malta for the provision of energy supplies and electricity, would have to become more self-sufficient in terms of renewable energy generation, thus reducing power transmission losses and its associated carbon emissions, and increasing the island’s autonomy and energy diversification. Studies showed that for the immediate future, there is a good potential for the use of solar and wind energy systems on the island. The use of bio-energy and alternative fuels for vehicles would increase energy options for transport fuel, and in the longer run, there might be possibilities for using wave energy for electricity production. The paper also shows significant savings that could be achieved by applying roof insulation to buildings. Although the paper has not exhaustively dealt with all energy saving, energy efficiency and renewable energy options, the results presented here should be useful to all entities who may be directly or indirectly involved in planning for the Eco-Gozo initiative, and may also support the formulation of sustainable action plans that would be necessary to achieve the full aims of the Eco-Island concept. This study also showed that the Island of Gozo could potentially even become a net exporter of green electricity.peer-reviewe

Assessing the design options for the optimisation of a 2MWp ground mounted PV system in Malta

The objective of large scale PV installations in space constrained countries has gradually shifted from production maximisation to that of reaching an optimised economic performance. The main reason for this is the ever decreasing price of the modules. This has resulted in systems with lower tilt angles, increased mutual shading and overloading of inverters by design, in the continuous quest of balancing reduced yield with development costs over the entire lifespan of the project. This approach has shifted the traditional view of evaluating a PV installation from a Euro/watt approach to the use of optimisation metrics such the Levelised Cost Of Electricity (LCOE) or Internal Rate of Return (IRR). Optimisation can be simply described as a balancing act, evaluating tradeoffs to assess which combination gives the best economic performance. By its very nature, optimisation is an iterative process. This paper evaluates a number of design parameters which, together with production modelling within the context of the Maltese solar climate, aims at identifying an optimum design for the building of a 2MWp ground mounted PV installation. Among the issues considered are; layout optimisation with issues of tilt, cross shading and cabling options, and inverter architecture whether string or central including dc-to-ac rating.Bajada New Energy, General Membrane, EcoGroup, Econetique, Energy Investment, JMV Vibro Blocks, Solar Engineering, Solar Solutionspeer-reviewe

Increasing PV module output with flat reflectors – a scenario in Malta

The output of photovoltaic (PV) modules is related to the solar radiation incident on their surface. The immediate surroundings of the modules may reflect a considerable amount of radiation on to them, thus affecting their performance and output. This paper explores ways of improving the output of PV modules installed in Malta, with the aid of flat plate reflectors installed in front of the modules. This study focused on the effect that different types of reflective materials have on the PV modules’ output. Two sets of reflectors were studied. The first set consisted of reflectors that can be set at an angle to the horizontal, while the second set emulates different flat roof surfaces. The output of PV modules was measured and compared for each case. Measurements started in October 2012 and are still ongoing. The aim is to study the effect of reflecting surfaces and the PV modules output, and to determine the effect of the inclination of reflector. Results have so far shown that a potential increase of up to 15% maybe achieved by aluminium reflectors during the winter seasons.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe