A review of photovoltaic module technologies for increased performance in tropical climate

The global adoption and use of photovoltaic modules (PVMs) as the main source of energy is the key to realising the UN Millennium Development Goals on Green Energy. The technology – projected to contribute about 20% of world energy supply by 2050, over 60% by 2100 and leading to 50% reduction in global CO2 emissions – is threatened by its poor performance in tropical climate. Such performance discourages its regional acceptance. The magnitude of crucial module performance influencing factors (cell temperature, wind speed and relative humidity) reach critical values of 90 °C, 0.2 m/s and 85%, respectively in tropical climates which negatively impact module performance indices which include power output (PO), power conversion efficiency (PCE) and energy payback time (EPBT). This investigation reviews PVM technologies which include cell, contact and interconnection technologies. It identifies critical technology route(s) with potential to increase operational reliability of PVMs in the tropics when adopted. The cell performance is measured by PO, PCE and EPBT while contacts and interconnections performance is measured by the degree of recombination, shading losses and also the rate of thermo-mechanical degradation. It is found that the mono-crystalline cell has the best PCE of 25% while the Cadmium Telluride (CdTe) cell has the lowest EPBT of 8-months. Results show that the poly-crystalline cell has the largest market share amounting to 54%. The CdTe cell exhibits 0% drop in PCE at high-temperatures and low irradiance operations – demonstrating least affected PO by the conditions. Further results establish that back contacts and back-to-back interconnection technologies produce the least recombination losses and demonstrate absence of shading in addition to possessing longest interconnection fatigue life. Based on these findings, the authors propose a PVM comprising CdTe cell, back contacts and back-to-back interconnection technologies as the technology with latent capacity to produce improved performance in tropical climates

Solar Resources and Carbon Footprint of Photovoltaic Power in Different Regions in Europe

The 2011 world average carbon footprint of PV system manufacturing is estimated as 1798 kg CO2- eq/kWp using technology shares (multi, mono, film Si, CdTe, CIGS) as weighting factors. The electricity mixes of all production countries of poly-Si, wafer, cell and modules was taken into account. New yearly irradiation data (kWh/m2) and PV energy output (kWh/kWp) are calculated for different regions in Europe on NUTS level 1 and 2 for horizontal, optimum and vertical angle. The world average carbon footprint of PV electricity generation is estimated as 55 g CO2- eq/kWh with cumulative installations as weighting factors. Lowest value of 38 g CO2-eq/kWh is for Cyprus which has a high irradiation and the highest value of 89 g CO2-eq/kWh is for Iceland which has a low irradiation. It is assumed that the PV modules are installed at optimal angle to the sun and end-of-life treatment is excluded. The majority of countries can decrease the greenhouse gas emission of electricity generation by increasing the share of photovoltaics.JRC.F.7-Renewables and Energy Efficienc

The energy payback time of advanced crystalline silicon PV modules in 2020 : A prospective study

The photovoltaic (PV) market is experiencing vigorous growth, whereas prices are dropping rapidly. This growth has in large part been possible through public support, deserved for its promise to produce electricity at a low cost to the environment. It is therefore important to monitor and minimize environmental impacts associated with PV technologies. In this work, we forecast the environmental performance of crystalline silicon technologies in 2020, the year in which electricity from PV is anticipated to be competitive with wholesale electricity costs all across Europe. Our forecasts are based on technological scenario development and a prospective life cycle assessment with a thorough uncertainty and sensitivity analysis. We estimate that the energy payback time at an in-plane irradiation of 1700 kWh/(m2 year) of crystalline silicon modules can be reduced to below 0.5 years by 2020, which is less than half of the current energy payback time

Life cycle inventories and life cycle assessment of photovoltaic systems

Report T12-04:201

Wafer-based crystalline silicon modules at 1€ /Wp : Final results from the CrystalClear integrated project

CrystalClear was an EU co-financed Integrated Project aimed at developing technology for waferbased silicon solar modules at 1 per watt-peak manufacturing costs and a strongly improved environmental profile. The project consortium has selected a number of technologies that potentially comply with these aims as well as research that serves as basis for further developments (beyond the project aims). These technologies have been demonstrated in the form of demonstrators, i.e. full-size modules featuring all innovations necessary to comply with the aims. The project has shown that wafer-based multicrystalline-silicon solar modules can be produced at 1 per watt-peak at a world-record efficiency of 16% and an energy pay-back time of less than 2 years in Southern Europe

Energy Return on Energy Invested (ERoEI) for photovoltaic solar systems in regions of moderate insolation:a comprehensive response

A recent paper by Ferroni and Hopkirk (2016) asserts that the ERoEI (also referred to as EROI) of photovoltaic (PV) systems is so low that they actually act as net energy sinks, rather than delivering energy to society. Such claim, if accurate, would call into question many energy investment decisions. In the same paper, a comparison is also drawn between PV and nuclear electricity. We have carefully analysed this paper, and found methodological inconsistencies and calculation errors that, in combination, render its conclusions not scientifically sound. Ferroni and Hopkirk adopt ‘extended’ boundaries for their analysis of PV without acknowledging that such choice of boundaries makes their results incompatible with those for all other technologies that have been analysed using more conventional boundaries, including nuclear energy with which the authors engage in multiple inconsistent comparisons. In addition, they use out-dated information, make invalid assumptions on PV specifications and other key parameters, and conduct calculation errors, including double counting. We herein provide revised EROI calculations for PV electricity in Switzerland, adopting both conventional and ‘extended’ system boundaries, to contrast with their results, which points to an order-of-magnitude underestimate of the EROI of PV in Switzerland by Ferroni and Hopkirk

Energy Return on Energy Invested (ERoEI) for photovoltaic solar systems in regions of moderate insolation: A comprehensive response

A recent paper by Ferroni and Hopkirk (2016) asserts that the ERoEI (also referred to as EROI) of photovoltaic (PV) systems is so low that they actually act as net energy sinks, rather than delivering energy to society. Such claim, if accurate, would call into question many energy investment decisions. In the same paper, a comparison is also drawn between PV and nuclear electricity. We have carefully analysed this paper, and found methodological inconsistencies and calculation errors that, in combination, render its conclusions not scientifically sound. Ferroni and Hopkirk adopt ‘extended’ boundaries for their analysis of PV without acknowledging that such choice of boundaries makes their results incompatible with those for all other technologies that have been analysed using more conventional boundaries, including nuclear energy with which the authors engage in multiple inconsistent comparisons. In addition, they use out-dated information, make invalid assumptions on PV specifications and other key parameters, and conduct calculation errors, including double counting. We herein provide revised EROI calculations for PV electricity in Switzerland, adopting both conventional and ‘extended’ system boundaries, to contrast with their results, which points to an order-of-magnitude underestimate of the EROI of PV in Switzerland by Ferroni and Hopkirk.JRC.C.2-Energy Efficiency and Renewable