More efficient PV panels by cooling and the Performance enhancement of a PV-driven boat by active cooling

Abstract: A competition named Frisian Solar Challenge is organized for solar boats every second year in Holland. A team from the European Solar Engineering School (ESES) at Högskolan Dalarna was participated twice in the race. In this thesis a theoretical design of a cooling system for a PV driven boat is presented and the benefit of that is investigated. The aim is to enhance the output power of the PV panels by way of reducing the cell temperature of the modules. If the panel can deliver more power for the electro-motor during the stages, the boat can go at a higher speed.The method of the design bases on combining the PV with Thermal collector (PVT). The idea is that an absorber plate with rectangular duct-like fluid channels contacting the entire surface is integrated in each of the PV modules by way of mounting with glue on the back sheet. Then all of the modules are interconnected in parallel according to the Tichelmann method. The system is filled with water, which is taken from the lake and forced by pump. In course of the calculation the volume of heat transferred from the PV to the fluid at a maximum fluid flow rate of 700l/hr based on the pump power was estimated first. For determining the transferred heat the fraction of solar radiation dissipated was necessary to define. The formula, which was derived by Matthias Rommel and Wolfgang Moock for the collector efficiency factor F’ of narrow-duct absorbers, was used for determining the transferred heat. After making a diagram containing the calculated values for PV module efficiency plotted against irradiance data from Amsterdam, a difference of 0.8% in efficiency at the highest solar radiation was obtained as a result of cooling. This means that under favourable conditions (I = 860W/m2; Ta = 17.5°C) almost 6% more power can be extracted by decreasing the cell temperature with 20 degrees. Then the overall pressure drop in the system was calculated for selecting the pump. The characteristic curve giving the relationship between the electro-motor performance and the boat speed in case of having a cooling system was made for investigating the benefit of the cooling system. The curve bases on measured data. For estimating the benefit of the cooling system the parameters of the last race such as the distance of the stages were taken as reference.Calculations show that the boat could go at a speed of 1km/h higher on average and the time benefit would be maximum 24 minutes (depending on the distance of the stage) on days with an irradiance of H (500-700) W/m2. On days with an irradiance of H (750-850) W/m2 the average top speed would be 2km/h higher and it would result in a racing time of 37 minutes shorter on average.