PV and Recyclebot/The case for open source appropriate technology

The case for open source appropriate technology^[1][edit | edit source]

Abstract

Much of the widespread poverty, environmental desecration, and waste of human life seen around the globe could be prevented by known (to humanity as a whole) technologies, many of which are simply not available to those that need it. This lack of access to critical information for sustainable development is directly responsible for a morally and ethically unacceptable level of human suffering and death. A solution to this general problem is the concept of open source appropriate technology or OSAT, which refers to technologies that provide for sustainable development while being designed in the same fashion as free and open source software. OSAT is made up of technologies that are easily and economically utilized from readily available resources by local communities to meet their needs and must meet the boundary conditions set by environmental, cultural, economic, and educational resource constraints of the local community. This paper explores both the open source and appropriate technology aspects of OSAT to create a paradigm, in which anyone can both learn how to make and use needed technologies free of intellectual property concerns. At the same time, anyone can also add to the collective open source knowledge ecosystem or knowledge commons by contributing ideas, designs, observations, experimental data, deployment logs, etc. It is argued that if OSAT continues to grow and takes hold globally creating a vibrant virtual community to share technology plans and experiences, a new technological revolution built on a dispersed network of innovators working together to create a just sustainable world is possible.

Open-source, self-replicating 3-D printer factory for small-business manufacturing^[2][edit | edit source]

Abstract

Additive manufacturing with 3-D printers may be a key technology enabler for entrepreneurs seeking to use disruptive innovations such as business models utilizing distributed manufacturing. Unlike centralized manufacturing, distributed manufacturing makes the parts and products (the prints) at (or closer to) the source of the demand, cutting out much of the traditional supply chain. Although many expect 3-D printing to take off at the household level and previous work has shown significant returns for those choosing to do so, there are still significant barriers to entry for typical consumers. Our analysis demonstrates that for an individual to make an abnormally high return on their investments in 3-D printers, they must serve others to achieve high utilization rates. The impetus to do so is created by a service that can undercut traditionally manufactured products due to affordability and customizability. Low-cost, open-source 3-D printers are now priced within range of individual entrepreneurs who can take advantage of the long tail of consumers with highly varied interests. The margin advantage, net present value, and return on investment (ROI) analysis provided herein could form the basis of thousands of new small-business ventures in the coming years

Combined low-cost, high-efficient inverter, peak power tracker and regulator for PV applications^[3][edit | edit source]

Abstract

A novel compound power converter that serves as a DC-to-AC inverter, maximum power point tracker (MPPT), and battery charger for stand-alone photovoltaic (PV) power systems is introduced. A theoretical analysis of the proposed converter is performed, and the results are compared with experimental results obtained from a 1.5 kW prototype. The overall cost of PV systems can thus be reduced by using load management control and efficiency-optimization techniques. Power flow through the converter is controlled by means of a combination of duty cycle and output frequency control. With load management, large domestic loads, such as single phase induction motors for water pumping, hold-over refrigerators, and freezers, can be driven by day at a much higher energy efficiency. This is due to the high efficiency of the inverter with high insolation, and because the inverter uses the energy directly from the solar array. The battery loss component is thus reduced.

Open-source development of solar photovoltaic technology^[4][edit | edit source]

Abstract

The rise of solar photovoltaic (PV) technology as a driver of rural electrification in the developing world and a contributor to climate change mitigation suggests that innovations enhancing PV efficiency and scalability could make considerable strides in reducing both poverty and greenhouse gas emissions. The nearly global access to the solar resource coupled to innovation-driven decreases in the costs of PV provides a path for a renewable energy source to accelerate sustainable development. Open-source software development has proven to produce reliable and innovative computer code at lower costs than proprietary software through sharing development responsibility with a large community of invested individuals. Concepts of open-source design have been applied to other fields in an attempt to reap the same benefits realized within software development; however, applying open-source strategies to solar PV research is uncommon. This paper reviews and examines how open-source design can be utilized to catalyze rapid innovation in the PV industry. The results show how successful open design and development methods can be created and utilized by identifying business models that provide PV researchers, turnkey suppliers and solar PV module manufacturers with the opportunity to utilize open-source design principles to accelerate innovation

Photovoltaic projects for decentralized power supply in India: A financial evaluation^[5][edit | edit source]

Abstract

The present study concentrates on photovoltaic (PV) projects for providing decentralized power supply in remote locations in India. Results of a techno-economic evaluation are presented. Some PV projects in the capacity range 1–110 kWp, that have either been implemented or are under implementation, have been considered. An analysis of the capital cost of the PV projects and sub-systems has been undertaken. Levelized unit cost of electricity (LUCE) has been estimated for eighteen select locations situated in different geographical regions of the country. The LUCE is found to vary in the range of Rs. 28.31–59.16/kW h (US$ 0.65–1.35/k Wh) for PV projects in the capacity range 1–25 kWp. In view of high unit cost of electricity from PV projects, need for financial incentives has been examined from the perspective of users. A sensitivity analysis has also been undertaken.

A review of the factors affecting operation and efficiency of photovoltaic based electricity generation systems^[6][edit | edit source]

Abstract

One of the most popular techniques of renewable energy generation is the installation of photovoltaic (PV) systems using sunlight to generate electrical power. There are many factors that affecting the operation and efficiency of the PV based electricity generation systems, such as PV cell technology, ambient conditions and selection of required equipment. There is no much study that presents all factors affecting efficiency and operation of the entire PV system, in the literature. This paper provides a detailed review of these factors and also includes suggestions for the design of more efficient systems. The presented detailed overview will be useful to people working on theory, design and/or application of photovoltaic based electricity generation systems.

Empirical investigation of the energy payback time for photovoltaic modules^[7][edit | edit source]

Abstract

Energy payback time is the energy analog to financial payback, defined as the time necessary for a photovoltaic panel to generate the energy equivalent to that used to produce it. This research contributes to the growing literature on net benefits of renewable energy systems by conducting an empirical investigation of as-manufactured photovoltaic modules, evaluating both established and emerging products. Crystalline silicon modules achieve an energy break-even in 3 to 4 years. At the current R&D pilot production rate (8% of capacity) the energy payback time for thin film copper indium diselenide modules is between 9 and 12 years, and in full production is ∼2 years. Over their lifetime, these solar panels generate 7 to 14 times the energy required to produce them. Energy content findings for the major materials and process steps are presented, and important implications for current research efforts and future prospects are discussed.

Life cycle assessment of photovoltaic electricity generation^[8][edit | edit source]

Abstract

The paper presents the results of a life cycle assessment (LCA) of the electric generation by means of photovoltaic panels. It considers mass and energy flows over the whole production process starting from silica extraction to the final panel assembling, considering the most advanced and consolidate technologies for polycrystalline silicon panel production. Some considerations about the production cycle are reported; the most critical phases are the transformation of metallic silicon into solar silicon and the panel assembling. The former process is characterised by a great electricity consumption, even if the most efficient conversion technology is considered, the latter by the use of aluminium frame and glass roofing, which are very energy-intensive materials. Moreover, the energy pay back time (EPBT) and the potential for CO2 mitigation have been evaluated, considering different geographic collocations of the photovoltaic plant with different values of solar radiation, latitude, altitude and national energetic mix for electricity production.

The viability of solar photovoltaics^[9][edit | edit source]

Abstract

This paper summaries the contributions to a special issue of Energy Policy aiming to assess the viability of solar photovoltaics (PVs) as a mainstream electricity supply technology for the 21st Century. It highlights the complex nature of such an assessment in which technical, economic, environmental, social, institutional and policy questions all play a part. The authors summarise briefly the individual contributions to the special issue and draw out a number of common themes which emerge from them, for example: the vast physical potential of PVs, the environmental and resource advantages of some PV technologies, and the fluidity of the market. Most of the authors accept that the current high costs will fall substantially in the coming decade as a result of improved technologies, increased integration into building structures and economies of scale in production. In spite of such reassurances, energy policy-makers still respond to the dilemma of PVs with some hesitancy and prefer to leave its evolution mainly in the hands of the market. This paper highlights two clear dangers inherent in this approach: firstly, that short-term cost convergence may not serve long-term sustainability goals; and secondly, that laggards in the race to develop new energy systems may find themselves faced with long-term penalties.

Industrial symbiosis of very large-scale photovoltaic manufacturing^[10][edit | edit source]

Abstract

In order to stabilize the global climate, the world's governments must make significant commitments to drastically reduce global greenhouse gas (GHG) emissions. One of the most promising methods of curbing GHG emissions is a world transition from fossil fuels to renewable sources of energy. Solar photovoltaic (PV) cells offer a technically sustainable solution to the projected enormous future energy demands. This article explores utilizing industrial symbiosis to obtain economies of scale and increased manufacturing efficiencies for solar PV cells in order for solar electricity to compete economically with fossil fuel-fired electricity. The state of PV manufacturing, the market and the effects of scale on both are reviewed. Government policies necessary to construct a multi-gigaWatt PV factory and complementary policies to protect existing solar companies are outlined and the technical requirements for a symbiotic industrial system are explored to increase the manufacturing efficiency while improving the environmental impact of PV. The results of the analysis show that an eight-factory industrial symbiotic system can be viewed as a medium-term investment by any government, which will not only obtain direct financial return, but also an improved global environment. The technical concepts and policy limitations to this approach were analyzed and it was found that symbiotic growth will help to mitigate many of the limitations of PV and is likely to catalyze mass manufacturing of PV by transparently demonstrating that large-scale PV manufacturing is technically feasible and reaches an enormous untapped market for PV with low costs.

Emissions from Photovoltaic Life Cycles^[11][edit | edit source]

Abstract

Photovoltaic (PV) technologies have shown remarkable progress recently in terms of annual production capacity and life cycle environmental performances, which necessitate timely updates of environmental indicators. Based on PV production data of 2004–2006, this study presents the life-cycle greenhouse gas emissions, criteria pollutant emissions, and heavy metal emissions from four types of major commercial PV systems: multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride. Life-cycle emissions were determined by employing average electricity mixtures in Europe and the United States during the materials and module production for each PV system. Among the current vintage of PV technologies, thin-film cadmium telluride (CdTe) PV emits the least amount of harmful air emissions as it requires the least amount of energy during the module production. However, the differences in the emissions between different PV technologies are very small in comparison to the emissions from conventional energy technologies that PV could displace. As a part of prospective analysis, the effect of PV breeder was investigated. Overall, all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel-based electricity generation technologies. At least 89% of air emissions associated with electricity generation could be prevented if electricity from photovoltaics displaces electricity from the grid.

Improved photovoltaic energy output for cloudy conditions with a solar tracking system^[12][edit | edit source]

Abstract

This work describes measurements of the solar irradiance made during cloudy periods in order to improve the amount of solar energy captured during such periods. It is well-known that 2-axis tracking, in which solar modules are pointed at the sun, improves the overall capture of solar energy by a given area of modules by 30–50% versus modules with a fixed tilt. On sunny days the direct sunshine accounts for up to 90% of the total solar energy, with the other 10% from diffuse (scattered) solar energy. However, during overcast conditions nearly all of the solar irradiance is diffuse radiation that is isotropically-distributed over the whole sky. An analysis of our data shows that during overcast conditions, tilting a solar module or sensor away from the zenith reduces the irradiance relative to a horizontal configuration, in which the sensor or module is pointed toward the zenith (horizontal module tilt), and thus receives the highest amount of this isotropically-distributed sky radiation. This observation led to an improved tracking algorithm in which a solar array would track the sun during cloud-free periods using 2-axis tracking, when the solar disk is visible, but go to a horizontal configuration when the sky becomes overcast. During cloudy periods we show that a horizontal module orientation increases the solar energy capture by nearly 50% compared to 2-axis solar tracking during the same period. Improving the harvesting of solar energy on cloudy days is important to using solar energy on a daily basis for fueling fuel-cell electric vehicles or charging extended-range electric vehicles because it improves the energy capture on the days with the lowest hydrogen generation, which in turn reduces the system size and cost.

A review of solar photovoltaic technologies^[13][edit | edit source]

Abstract

Global environmental concerns and the escalating demand for energy, coupled with steady progress in renewable energy technologies, are opening up new opportunities for utilization of renewable energy resources. Solar energy is the most abundant, inexhaustible and clean of all the renewable energy resources till date. The power from sun intercepted by the earth is about 1.8 × 1011 MW, which is many times larger than the present rate of all the energy consumption. Photovoltaic technology is one of the finest ways to harness the solar power. This paper reviews the photovoltaic technology, its power generating capability, the different existing light absorbing materials used, its environmental aspect coupled with a variety of its applications. The different existing performance and reliability evaluation models, sizing and control, grid connection and distribution have also been discussed.

Solar photovoltaic electricity: Current status and future prospects^[14][edit | edit source]

Abstract

We review the technical progress made in the past several years in the area of mono- and polycrystalline thin-film photovoltaic (PV) technologies based on Si, III–V, II–VI, and I–III–VI2 semiconductors, as well as nano-PV. PV electricity is one of the best options for sustainable future energy requirements of the world. At present, the PV market is growing rapidly at an annual rate of 35–40%, with PV production around 10.66 GW in 2009. Si and GaAs monocrystalline solar cell efficiencies are very close to the theoretically predicted maximum values. Mono- and polycrystalline wafer Si solar cells remain the predominant PV technology with module production cost around $1.50 per peak watt. Thin-film PV was developed as a means of substantially reducing the cost of solar cells. Remarkable progress has been achieved in this field in recent years. CdTe and Cu(In,Ga)Se2 thin-film solar cells demonstrated record efficiencies of 16.5% and almost 20%, respectively. These values are the highest achieved for thin-film solar cells. Production cost of CdTe thin-film modules is presently around $0.76 per peak watt.

Increasing the solar photovoltaic energy capture on sunny and cloudy days^[15][edit | edit source]

Abstract

This report analyzes an extensive set of measurements of the solar irradiance made using four identical solar arrays and associated solar sensors (collectively referred to as solar collectors) with different tilt angles relative to the earth's surface, and thus the position of the sun, in order to determine an optimal tracking algorithm for capturing solar radiation. The study included a variety of ambient conditions including different seasons and both cloudy and cloud-free conditions. One set of solar collectors was always approximately pointed directly toward the sun (DTS) for a period around solar noon. These solar collectors thus captured the direct beam component of the solar radiation that predominates on sunny days. We found that on sunny days, solar collectors with a DTS configuration captured more solar energy in accordance with the well-known cosine dependence for the response of a flat-surfaced solar collector to the angle of incidence with direct beam radiation. In particular, a DTS orientation was found to capture up to twice as much solar energy as a horizontal (H) orientation in which the array is tilted toward the zenith. Another set of solar collectors always had an H orientation, and this best captured the diffuse component of the solar radiation that predominates on cloudy days. The dependence of the H/DTS ratio on the solar-collector tilt angle was in approximate agreement with the Isotropic Diffuse Model derived for heavily overcast conditions. During cloudy periods, we found that an H configuration increased the solar energy capture by nearly 40% compared to a DTS configuration during the same period, and we estimate the solar energy increase of an H configuration over a system that tracks the obscured solar disk could reach 50% over a whole heavily-overcast day. On an annual basis the increase is predicted to be much less, typically only about 1%, because the contribution of cloudy days to the total annual solar energy captured by a photovoltaic system is small. These results are consistent with the solar tracking algorithm optimized for cloudy conditions that we proposed in an earlier report and that was based on a much smaller data set. Improving the harvesting of solar energy on cloudy days deserves wider attention due to increasing efforts to utilize renewable solar energy. In particular, increasing the output of distributed solar power systems on cloudy days is important to developing solar-powered home fueling and charging systems for hydrogen-powered fuel-cell electric and battery-powered vehicles, respectively, because it reduces the system size and cost for solar power systems that are designed to have sufficient energy output on the worst (cloudy) days.