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The high share of power generation based on fluctuating renewable energy sources, especially wind and solar, has increased the levels of variability and uncertainty in power systems. The aim of this study is to develop a method for quantifying the variability of photovoltaic (PV) systems. The developed method investigates the power measurements of a PV system and quantifies its power and energy fluctuations in three steps. The first includes a classification of days into three classes according to the variability and power output of the PV system. The second consists of computing the empirical cumulative distribution functions of PV power ramps for the given classes. The third calculates the PV daily energy fluctuations based on predicted PV power output. This method of PV variability quantification was then applied to seven rooftop PV systems in different locations that feature different installed capacities, years of installation, orientations and solar cell types. The testing of this method indicates that it can be used to quantify the power and energy fluctuations of different PV systems, independent of their locations and technical characteristics. The proposed method was developed as part of a general approach for quantifying the flexibility potential of buildings and city districts with PV systems. [ABSTRACT FROM AUTHOR]

Small‐scale systems are vulnerable to changes. The development of solution strategies for changing conditions should, therefore, be considered from the outset in planning. For planners and installers of mini‐grids for rural villages without grid connection, first of all, the question of the expected electricity demand arises. So far, this is determined primarily by interviewing the population. However, studies have shown that there are still major differences between the power demand estimated and the real load after electrification. Reinforcing here is the inadequate assessment of load development through immigration and increased prosperity. On the basis of a currently developing mini‐grid in the Eastern Cape of South Africa, we could show that a load increase of ∼60% within 10 years is to be expected. The following possibilities were outlined as possible ways of counteracting the increase in load: (i) communicating with the population, i.e. on energy efficiency to raise awareness and understanding, (ii) early planning of capacity building and identification of key performance parameters to trigger the expansion based on local socio‐cultural conditions and grid supporting qualities. An adequate database for the initial electrification and power development should also be established and available on open‐source basis for researchers, developers, communities, and installers. [ABSTRACT FROM AUTHOR]

For a viable and commercial attractive integration of vehicle integrated photovoltaic applications (ViPVs) energy forecasting is required as a foundation for business case calculation. The developed algorithm facilitates the forecast of annual power distribution and solar energy yield along any given track tested on a German use case. A high temporal and spatial resolution of the meteorological database providing ambient temperature, wind speed, and global horizontal irradiance was determined as a necessity to preserve the irradiance distribution and consequently the power distribution available throughout the year. For ViPV module temperature, respectively, module efficiency benefits strongly from head wind. As a consequence, the performance of ViPV under motion was identified as superior to non-mobile PV installations. The potential annual energy yield of the three showcasing commercial semi-trailer lorries operating in Germany is identified to be 3-7 MWh depending on the used cell technology. The potential energy gain due to head wind cooling is estimated to be 20-75 kWh per trailer and year. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Solar cells used in building integration of photovoltaic cells ( BIPV) are commonly made from crystalline wafer cells. This contribution investigates the challenges and benefits of using bifacial solar cells in vertical installations. We show that those cells get up to 13% more irradiance compared to optimum tilted south facing monofacial modules in Germany. The role of the n-layer in thin amorphous bifacial single-junction cells intended to be used as bifacial cells in BIPV applications is investigated. In contrast to the superstrate cell design, a transparent n-layer and back contact play a key role to achieve high bifaciality. We therefore increased the transparency of the n-layer by adding CO2, increasing the PH3 flow in the deposition gas and tested different thicknesses. With those measures, we reached a bifaciality of 98% for short-circuit current density and 99% for open-circuit voltage. [ABSTRACT FROM AUTHOR]