PV-battery and diesel hybrid system for irrigation of a farm in Patagonia

An existing off-grid irrigation system of a 12’000 ha farm in Patagonia today powered by electrical pumps and diesel gensets, will be extended by a PV plant and a battery system to improve ecological ratings of the products and reduce energy costs. An optimal photovoltaic plant and a battery energy storage system had to be designed. The compiled hourly demand profile served as input to a simulation model of a photovoltaic diesel battery hybrid system. With the given assumptions the PV array should be oriented to north at an inclination of 30°. The analysis of electricity cost indicated the optimal system size of 1800 kWp PV nominal power and 500 kWh of battery capacity. With this system 55.2% of the energy used for irrigation will be provided by the photovoltaic plant in the first year. The electricity cost amount to $0.136 per kWh electrical energy compared to the$0.432 per kWh electrical energy currently produced by the diesel-only system. Further analysis showed high dependency of the electricity cost on the time until connection to the utility grid and its electricity price and future diesel price

Techno-economic evaluation of voltage dependent active and reactive power control to reduce voltage violations in distribution grids

High penetration of PV plants or numerous electric vehicle (EV) charging station stations connected to the low voltage distribution grids (LVDG) may cause a voltage rise or voltage decrease respectively. There are several measures of maintaining the voltage stability such as grid reinforcement, battery energy storage, line voltage regulator, etc., although they vary in effectiveness and economic viability. This paper focuses on using decentralised voltagedependent active and reactive power (PQ(V)) control of PV inverters to stabilise the voltage in the grid. Using two grid models in Southern Germany and Switzerland the best PQ(V) control strategy is evaluated using load flow calculations. The weakest node in the first grid exhibits a maximum voltage of 1.072 pu on a sunny day. Due to the implementation of the PQ(V) control the maximum voltage is reduced to 1.024 pu at the same node. Costs considered for PQ(V) control are the PV yield loss and the additional reactive power compensation, which amount to roughly CHF 2’600.- per year. The future installation of EV charging stations may positively interact with PV feed-in. The voltage decrease can further be limited using PQ(V) control. Further grids and means for voltage stabilisation will be analysed in the future

New PV system concept : inductive power transfer for PV modules

The proposed new PV system concept is based on several AC modules that are connected in series using inductive power transfer. These modules include a cell matrix that is connected to a module integrated DC/AC inverter. The high frequency AC current flows through the primary side planar coil generating a magnetic flux. Outside of the PV module, there is a clamp including ferromagnetic material for the magnetic circuit that caries the magnetic flux to the secondary winding. The magnetic flux induces an AC current in the secondary winding, which is formed by the common cable. An AC/AC converter is placed at the end of the PV module strings to generate the 50 Hz and to connect the PV power plant to the electricity grid. This new PV system concept is a fundamentally new approach of the electricity transmission in the field of PV system technology. It is not restricted to the replacement or optimisation of an individual system component, but it requires the continuing development of the PV module construction and the contactless connection technology to the common cable. The proposed inductive power transfer per each PV module opens up a complete new field for the PV system technology

Performance analysis of vertically mounted bifacial PV modules on green roof system

A combination of PV and green roof is an ideal fusion in terms of ecology. The green roof improves the water retention in the city, whereas the PV system produces electric power at the place where it is consumed. Flat tilted modules in south or east west direction on green roofs generally require intensive maintenance to prevent them from being shaded by plants and often cover the roof area to a large extent. Because of the space requirement conflict between PV on the roof and green roofs, it is essential to combine these two systems in a smart way. Vertically mounted bifacial modules can be an option to combine PV and green roof and to also allow a cost-effective maintenance. In this paper we report about the layout and the performance of a corresponding system, subdivided into two groups with differing albedo. Custom made bifacial modules with 20 cells were produced to reduce the wind load and to improve the general appearance. This 9.09 kWp bifacial plant achieved a specific yield of 942 kWh/kWp in one year (11.08.2017 to 10.08.2018). High quality DC power measurement systems are installed to monitor two modules in each bifacial test field and a reference south-facing module. This allows an energy yield comparison between the vertical bifacial test system with east-west orientation and the monofacial south-facing reference over four months of outdoor measurements. The use of plants with good reflective properties, which are also well suited two the ambient conditions on flat roofs, resulted in a yield increase of 17 % compared to a standard green roof planting. The vertically installed bifacial modules obtained an almost identical specific yield (-1.4 %) compared to a stand-alone monofacial southfacing reference module. Due to the increased yield in the mornings and afternoons, the vertical bifacial modules can achieve higher self-consumption depending on the load profile

Evaluating automated longitudinal tumor measurements for glioblastoma response assessment.

Automated tumor segmentation tools for glioblastoma show promising performance. To apply these tools for automated response assessment, longitudinal segmentation, and tumor measurement, consistency is critical. This study aimed to determine whether BraTumIA and HD-GLIO are suited for this task. We evaluated two segmentation tools with respect to automated response assessment on the single-center retrospective LUMIERE dataset with 80 patients and a total of 502 post-operative time points. Volumetry and automated bi-dimensional measurements were compared with expert measurements following the Response Assessment in Neuro-Oncology (RANO) guidelines. The longitudinal trend agreement between the expert and methods was evaluated, and the RANO progression thresholds were tested against the expert-derived time-to-progression (TTP). The TTP and overall survival (OS) correlation was used to check the progression thresholds. We evaluated the automated detection and influence of non-measurable lesions. The tumor volume trend agreement calculated between segmentation volumes and the expert bi-dimensional measurements was high (HD-GLIO: 81.1%, BraTumIA: 79.7%). BraTumIA achieved the closest match to the expert TTP using the recommended RANO progression threshold. HD-GLIO-derived tumor volumes reached the highest correlation between TTP and OS (0.55). Both tools failed at an accurate lesion count across time. Manual false-positive removal and restricting to a maximum number of measurable lesions had no beneficial effect. Expert supervision and manual corrections are still necessary when applying the tested automated segmentation tools for automated response assessment. The longitudinal consistency of current segmentation tools needs further improvement. Validation of volumetric and bi-dimensional progression thresholds with multi-center studies is required to move toward volumetry-based response assessment

Mechanobiological Principles Influence the Immune Response in Regeneration: Implications for Bone Healing

A misdirected or imbalanced local immune composition is often one of the reasons for unsuccessful regeneration resulting in scarring or fibrosis. Successful healing requires a balanced initiation and a timely down-regulation of the inflammation for the re-establishment of a biologically and mechanically homeostasis. While biomaterial-based approaches to control local immune responses are emerging as potential new treatment options, the extent to which biophysical material properties themselves play a role in modulating a local immune niche response has so far been considered only occasionally. The communication loop between extracellular matrix, non-hematopoietic cells, and immune cells seems to be specifically sensitive to mechanical cues and appears to play a role in the initiation and promotion of a local inflammatory setting. In this review, we focus on the crosstalk between ECM and its mechanical triggers and how they impact immune cells and non-hematopoietic cells and their crosstalk during tissue regeneration. We realized that especially mechanosensitive receptors such as TRPV4 and PIEZO1 and the mechanosensitive transcription factor YAP/TAZ are essential to regeneration in various organ settings. This indicates novel opportunities for therapeutic approaches to improve tissue regeneration, based on the immune-mechanical principles found in bone but also lung, heart, and skin

New PV system concept : wireless PV module prototype

A first wireless PV module prototype is presented. The energy transfer from the solar cells to the string cable is done using the inductive power transfer technology. A half-bridge LLC resonant converter is designed for the DC/AC conversion. The wireless module consists of 60 half-cells and an integrated planar coil. The resonant converter is not yet integrated into the module, but it can be connected externally to the planar coil. The energy is transferred from the primary coil to the secondary planar coil placed outside of the PV module on top of the primary coil. An active rectifier is connected to the secondary coil and it feeds the DC system cable. The first measurements yielded in an efficiency of 88.2 % including the resonant converter, the inductive power transmission and the active rectifier efficiencies. The corresponding output was 207 W

Field testing of portable led flasher for nominal power measurements of pv-modules on-site

Nominal power measurements of individual PV modules are needed to quantify the critical modules of PV plants offering lower energy production than expected. Today’s state of the art procedure of shipping a small number of modules to a laboratory is time- and cost intensive and it bears the chance of accidental damage. The Portable LED Flasher (PLF) was developed to require no dismounting of the modules. The quality of the PLF was tested on three PV plants in Switzerland. Additionally, ten PV modules of each plant were measured in the certified indoor laboratory of SUPSI, resulting in a maximum deviation of 3% of the STC values. Furthermore, a round robin test on a single crystalline silicon reference module at 25°C was performed at the JRC’s ESTI laboratory, the Swiss Mobile Flasher Bus and SUPSI resulting in a maximum deviation of the mean values below 1% compared to the PLF. A throughput of up to 150 modules or 500 modules respectively per day is expected and the total measurement costs are estimated to be about a tenth of the costs compared to an indoor laboratory. Module temperature measurement is crucial for a low total uncertainty. Thus, methods such as pre-shadowing of the module and approximation of cell temperature are the current focus of further improvement of the PLF measurement method