Location: Oslomej, North Macedonia
Capacity: 10 MW
Goal of the study: Optimal site selection and energy yield assessment
Challenge: On-site data collection
One of the first steps of a prospective PV plant is site selection. The availability of the solar resource at the location is the greatest contributor to the feasibility of the project, and the solar resource estimate is the highest driver to the uncertainty that typically ranges from 5% to 17%. Reducing uncertainty is key to minimizing the risk, and correlates a higher financial viability and a greater confidence about the prospective PV system.
Open field locations are prefered over hilly terrains or sites that have hills in the vicinity that may obstruct the sunrays. But, sometimes the choice has to be made between sites that are in hilly terrains and data is needed to make an educated decision. Such was the case with the Oslomej 10 MW plant.
4 candidate sites were chosen by the client to be analysed. For that purpose, 8 Solar Data Collector devices were installed at the sites to collect irradiation, temperature and humidity data for a period of one year. The data was periodically transferred using 3G network connectivity to a cloud based database for further analysis. Preventive maintenance, cleaning the sensors and checking the device operation was done at periods ranging from 1 to 2 months.
One year of data is not sufficient for feasibility analysis, as it can not represent interannual variability of the weather. With the use of correction and interpolation techniques, satellite data of more than 10 years were corrected to match the characteristics captured by the on-site sensors. This corrected dataset was then transformed into a typical meteorological year, which can be used for feasibility assessment.
The findings were that there was an 8% difference in the total sum of irradiation between the least and best performing site. The effect on the energy yield was estimated by simulation to be in the same range. The difference of irradiation was attributed to the terrain and microclimate of the sites.