Effect of tilt angle on the performance of a thin-film photovoltaic system

Solar energy is among the cleanest and most sustainable ways to enhance electrical supply's resiliency and reliability for domestic and industrial use. A Photovoltaic (PV) system is the most effective way of capturing solar energy. Long-term warranty, low-cost maintenance, and vast resource availability, solar power generation has an advantage over other approaches. Thin-film technology PV cells are a new kind of solar cell that offers an efficient technique of generating electricity from sunlight. The thin-film PV technology (FFMAT-10, Renovagen, UK) used in this study can supply 0.9 to 1.6 kW of energy to the fast-fold energy hub. The hub’s system status and configuration display battery power input, battery’s state of charge, thin-film PV power and AC power output. Two fast-fold mats (with a surface area of 25.3 m2) were connected to the energy hub. Increasing energy demand coupled with frequent power outages, and inaccessibility of electricity in rural areas necessitates the usage of PV systems at their best performance level. The study objective, therefore, sought to assess the effect of tilt angle on the performance of the thin-film PV system. The study was conducted at Kimicha in Kirinyaga County Kenya, and Juja, Kenya at tilt angles between 0o to 30o. The results indicated that the mean peak PV power for Kimicha was 347.8±231.9 W at 5o and 517.7± 131.3 W at 15ofor Juja. The maximum solar radiation during the study period was 1086.4 ±211.4 W/m2 for Juja and 973.5±219.93 W/m2 for Kimicha. From the study, it was realized that an optimal tilt angle yields optimum solar radiation that translates to maximum power production. Even though the study was conducted in two different regions, it may be applied to any other geographical location. The outcome of the study aids in acquiring self-sustaining power in the most remote locations where electricity is scarce as well as improving energy security

Reducing Cooling Demands in Sub-Saharan Africa: a Study on the Thermal Performance of Passive Cooling Methods in Enclosed Spaces

The paper aims to explore the effect of different passive cooling measures using thermal modelling and predicting. Solar shading, green roofs and cool paints were incorporated as passive cooling measures to evaluate their combined effects on indoor environment, thermal comfort and its importance in energy conservation. A field experiment study was conducted in the sub-Saharan climate of Kiambu, Kenya where microclimate indicators were measured for validating and predicting the thermal behaviour. For this study, both mechanical and natural ventilation were restricted. Modelling and prediction were done in Design Builder and EnergyPlus software. The computer model was validated with data measured for 20 days on the field. A correlation value of 0.85 between the predicted values and the observed values was recorded. This result shows that this energy prediction process can provide reasonable predictions in cooling loads and the effect of passive cooling in reducing indoor temperature gains

CHARACTERISATION AND QUANTIFICATION OF BIOPROCESSING EFFLUENTS FROM COFFEE, DAIRY AND TANNERYPLANTS

There is an increasing rate of environmental pollution resulting from high emission rates from bioprocessing industries in Kenya. This study provides information on the characterization of bioprocessing effluents from 3 industries in Kenya. To achieve this, samples of effluents were collected from the 3 industries and then transported using plastic containers to JKUAT chemistry laboratories within 24 hours for analysis. Each sample was divided into 3 different 500 ml bottles, and the experiment was replicated 3 times. Physico-chemical parameters such as total dissolved solids (TDS), biological oxygen demand in 5 days at 20°C (BOD 5 ), pH, total solids (TS), total suspended solids (TSS), chemical oxygen demand (COD) and electrical conductivity (EC) of collected samples were analysed. The mean concentration levels were found to be (118±5, 176±10, and 128±3) for COD and (1200±2,800±1 and 700±6) for BOD 5 for dairy, coffee, and tannery effluents, respectively. These values were found to be slightly higher than the standard removal levels. The pollutant levels noticed at the different industries were notably high in tannery with 286 mg/l and least in the dairy effluents with 28mg/l. Based on the results obtained, there is need to treat effluents before discharging to water bodies

PERFORMANCE EVALUATION OF AN EVAPORATIVE CHARCOAL COOLER UTILIZING THIN-FILM PHOTOVOLTAIC SYSTEM FOR PRESERVATION OF AVOCADO

Fruits are high moisture agricultural produce rendering them highly perishable hence the danger of postharvest losses is also lurking when there are inadequate storage facilities. The losses result from physical, chemical, and physiological changes that are triggered by the loss in moisture content. Preservation of fruits using available and affordable technologies (such as charcoal coolers) can benefit small-scale farmers in minimizing postharvest losses. An evaporative charcoal cooler 4 m long, 4 m wide, and 2.5 m high providing a 40 m3 storage capacity was utilized in the study. The cooler with a 150 mm wide cavity filled with charcoal had a perforated pipe connected to a 1000-litrecistern raised at 2.5 m above the ground and connected to a water pump (Pedrollo PKm 60, Italy) that kept the charcoal wet by a drip system. The pump and the three axial fans (REC-21725 A2 W, USA) rated 180 cubic feet per minute (CFM) and 2600 revolutions per minute (RPM) were powered by fast fold thin-film PV (FFMAT-10, Renovagen, UK) system connected to a 10-kWh rated energy hub (FFENERGYHUB-10, Renovagen, UK). Temperature, relative humidity and product quality parameters (weight loss, total soluble solids, vitamin C content and firmness were evaluated).The evaporative cooler temperatures reduced significantly (P<0.05) with an average 25.0±0.37 oC and 32.1±0.99 ºC outdoors temperatures. The cooler relative humidity increased significantly (P˂0.05) averaging 76.8±1.6% and 43±2.8% for ambient conditions. The average cooling efficiency in the charcoal cooler was 83.0%.The percentage weight loss of the avocado was 3.9% and 7.5% for the cooler and outdoors respectively. The percentage vitamin C loss was 39.0% for the cooler and 49.6% for those kept outside. The total soluble solids in the cooler rose from 0.5 to 1.6 oBrix and 0.5 to 2.6 oBrix in ambient conditions. Firmness decreased from an average 65.0 N to 10.7 N and 65.0 N to 8.0 N after 12 days for samples in the cooler and ambient conditions, respectively. In conclusion, the evaporative charcoal cooler incorporated with thin-film PV system preserved the postharvest quality and extended the shelf life of hass avocado