Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
This thesis was aimed at validating an Excel tool developed by Energicity Company. In addition, to study a commercial software that can be used to design a solar mini-grid system for the company.
A 9.9 kW solar mini-grid in Bekwai, Ghana was used as a case study. Weather data from Meteonorm and component specification was used as input parameter for the simulation works.
HOMER pro and PVsyst commercial software were selected to validate the Excel tool. Each software was also explained in detail.
The validation was done by comparing input parameters and simulation results of the Excel tool with the selected commercial software. The process was divided into two main parts. The first part was, comparing the mathematical model, and the PV array electricity production of the software used as an input to the Excel tool, which was SAM, with HOMER pro and PVsyst. The second part was comparing the final simulation result of both tools, including the Excel tool.
The comparison result shows that the difference in the mathematical model for the diffuse irradiation in each software leads to a difference in the electricity production at the PV array output. Even though the difference is not significant for a small scale mini-grid system, the difference can cause a wrong estimation for critical loads, where a higher percentage of availability is required.
The DC losses at the PV array has a notable impact on estimating the electricity production. PVsyst considers more loss parameters than SAM and HOMER pro. As a result, the simulation result of the PVsyst shows lower electricity production at the output of the PV array compared to the others. This indicates as PVsyst is a more conservative software model.
The loss in the battery has another significant impact on estimating the energy delivered to the load. The battery model for each tool was different. The Excel tool uses higher battery loss percentage. Due to this, the energy served to the load by the Excel tool was lower than HOMER pro and SAM. HOMER pro’s estimation of the battery loss was almost equal to the Excel tool. The battery loss estimated by PVsyst was lower than all models. However, there were uncertainties in the input parameters of the battery, because of most of the parameters provided by the battery manufacturer was not compatible with the input parameters required by PVsyst.
2018.