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Analyzing Solar impact using Geospatial tools

Pratichhya Sharma

January 3, 2021

I am planning to move to Salzburg as a working resident and thus I decided to do some basic study on resident location before renting a house. Since Salzburg is mostly cold, I would prefer to have an area where I will have direct Sun rays every time it shines and I also want to install a solar panel on the roof to save electricity bills. In my study, I decided to analyze the area exposed to the sun; Sunshine duration and solar radiation at that location for a defined period.

Area of Interest

I chose the locality where I had previously stayed. This area is far from City Center but is calm and doesn't have much high rise buildings.

Digital Surafce Model

For the analysis, I used a 1m Digital Surface Model (DSM) provided by ZGIS for my Area of Interest.

Hillshade

With the use of NOAA Solar Calculator, Hillshade for the Area of Interest on 20th September 2020 at 1 pm in the afternoon is generated for better visualization of the DSM. Generated Hillshade is used to determine the illumination of the surface from a specific sun angle, corresponding to a particular date and time of the day.

To calculate the Sun Angle, as suggested, Lat and Long for Salzburg were fed in with the date of interest into the NOAA Solar Calculator . The angular direction of the sun(azimuth) as179.63 degrees and angle of illumination of the Sun above the horizon (altitude) as 43.03 degrees was computed.

The pink, red and green line on the map is shows the azimuth direction of the sun for a given date and time, during sunset and sunrise at the location respectively.

From the Hillshade Map, we can say that there is plenty of areas that are exposed to the sun at the defined time on September 20 of 2020.

With the Hillshade we can now differentiate between several elevated features and can assume that higher the elevation of the building, less will be the shade on neighbouring features.

Solar Radiation

Shortwave for solar energy depends on numerous factors, including latitude, time of the day and year, state of the atmosphere at that time and topography. To know the amount of Solar Radiation in this area I chose to use Area Solar Radiation tool of ArcGIS. It provided me with a raster for the same day of the year (264th day), that showed the incoming solar radiation ranging from 998 W/m² to 3554 W/m². In this case, atmospheric parameters are assumed to be favorable and not included in the calculation.

Solar Radiation on Specific Time of a Day in a Year

The map shows the shades red areas experiencing a comparatively greater amount of Sun hours than blue area. This map will provide me with an idea of where to place a photovoltaic power plant to get more sun hours by identifying the buildings with red or orange rooftops.

Similarly, whole year Solar Radiation over the area was calculated and the map shown below was obtained as a result. It shows that very less area are exposed to almost the same sun hours throughout the year.

Based on visual observation of the Solar Radiation at a specific day of the year and throughout the year, few buildings were selected as the most suitable locations in the overall locality buildings for the installation of solar panels on the rooftops or on that specific areas. Most of these buildings were observed on the south-east in the Area of Interest.

Observation

The sun radiation in the area varies from time to time and in case of a situation when I feel like growing crops which might require constant solar radiation, choice of time of the year is necessary. Using the same geospatial tool for Solar Radiation over the radiation, different maps were generated as shown in the figure below.

Solar Radiation for different period in a month

From the figure, we concluded that more solar radiation can be received from the Month of May until August which might be a suitable time for the cultivation of crops like Sunflower. The choice of location for these crops would be the area will more dark red colours. To be more sure for the incoming solar radiation, mean for each layer was computed and plotted that gave a better visualization for the Solar Radiation over an area in different period of time. With these outcomes, I decided that I will be planting my sunflower seeds near the South-East part of the Area of Interest in the beginning of May so that I can get harvest by the end of August.

But I don't want a whole garden of sunflower but few plants, for this I thought to chose a few locations based on my study until now and among them chose the most suitable. In the South-East part, I manually chose 9 location for the Sunflower plants as shown in the figure.

These points were fed into the Solar Analysis Geospatial tool i.e. Point Solar Radiation to know the most suitable location among these. From the graph obtained in the process, I realized that if I plant my sunflower at point 8 it will receive the maximum solar radiation whereas in point 9 it will receive the minimum. Thus I decide to plant the seeds in two locations 8 and 5.

Comparision of Mean Solar Radiation at Different Point

Conclusion

From my results, I can conclude that values for Solar Radiation are more for one day (264th day) than that for the whole year. The reason could be that the Solar Radiation was calculated for half an hour interval during Autumn afternoon. Whereas, for the entire year, the Solar Radiation was calculated for different seasons with a specific month interval.