METHODS IN SPATIAL ANALYSIS
MY LAB ASSIGNMENT ON SUNSHINE DURATION / SOLAR ENERGY
INTRODUCTION
Solar energy is the technology used to harness the sun's energy and make it usable. Solar energy is lauded as an inexhaustible fuel source that is pollution and often noise-free.
In this assignment, I created a solar energy "roof cadastre" for a community by estimating solar power potential of part of Elsbethen - Glasenbach region over a period of one year. This helped in determining how much electricity could be generated from solar power.
Various processes were carried out to achieve the aim of this task and they were as explained below:
APPROACH
STUDY AREA
For this task, part of Elsbethen - Glasenbach region was chosen as the study area. The green outline denote the boundary of the study area as shown on this slide.
SOFTWARE AND DATA USED
ArcGIS Pro was the adopted software for the task. The "1m DSM (Digital Surface Model) raster image" as available on the ZGIS server in ArcGIS Pro was used to accomplish the task.
It is necessary to use the DSM data since it shows the elevation of the ground as well as the features (buildings and trees) which will aid full actualization of the aim of the assignment in terms of result analysis.
THE PROCESSES
The ZGIS server was connected using the "connection" tool in the ArcGIS Pro and the DSM raster data was loaded into the content pane interface.
CLIPPING OF THE DSM RASTER DATA
The study area DSM was clipped from the original DSM data using the "Clip Raster" tool in order to avoid any delay in the processing time. The map shown in this slide is the clipped DSM of the study area which was later used for the analysis.
GENERATING THE HILLSHADE EFFECT
The Hillshade was generated using the "Hillshade" tool in the geoprocessing tool. The clipped DSM was used as the input raster. The following parameters were used as obatined from the NOAA Solar Calculator for my study area:
Azimuth :- 247 degrees
Altitude :- 23 degrees
At the end of the process, the Hillshade was created as seen in this slide.
Features like Buildings, trees are more distinguishable due to the effect of the hillshade. It's also possible to distinguish whether buildings have sloped or flat roofs which is important for rooftop solar panels.
VECTOR LAYER FOR BUILDINGS
For proper analysis, there is need to have the vector layer of the buildings within the study area and the shapefile for the buildings in Austria as existed on the Open Street Map (OSM) was used. The shapefile was downloaded from the OSM website written below:
After the download, the shapefile was added into the content pane of my project using the "Add data" tool and shapefile was clipped to only show the buildings within the study area.
The buildings was overlayed on the DSM to ascertain its positioning in terms of location and the map in this slide shows the result.
GENERATING THE SOLAR RADIATION
It is necessary to determine how much solar energy reaches rooftop surfaces in the study area over the course of the specified time (one year).
The "Area Solar Radiation" tool was adopted for this process and since it is important to determine the effect of the solar over this certain period. Some parameters were set which were as listed below:
Latitude :- 47.76 degrees
Sky Size / Resolution :- 200
Time Configuration :- Whole year (2019)
Hour Interval :- 1 hour
Calculation Direction :- 16
In the environment menu of the ArcGIS Pro, the clipped building layer for the study area was chosen as the mask since the interest is on the rooftop surface and not the ground surface.
The Solar Radiation map was generated as shown in this slide. So, it can be seen that different colours (orange, yellow and blue) exists in the map however, orange colour depicts higher level (amounts) of solar radiation while yellow and blue colours depicts lower amounts.
Furthermore, it can be observed that the more solar energy a roof surface receives, the more electric power could be generated if it were equipped with solar panels.
IDENTIFYING SUITABLE ROOFTOPS
This process was carried out in order to identify the rooftops that are suitable for the solar panels. Rooftop slope and orientation need to be determined to achieve this aim.
- So, to determine rooftop slope, slope map was created using the "Slope Spatial Analyst Tool".
Also, to determine rooftop orientation, aspect map was created using the "Aspect Spatial Analyst Tool". This slide contains the Slope and Aspect map.
In the slope map, each cell in this layer contains a slope value ranging from 0 to 90 degrees. this implies that the lighter colors represent lower slopes while darker colors represent steeper slopes.
In the aspect map, each cell contains a value expressing orientation in degrees, with 0 representing absolute north and 180 representing absolute south. The layer's legend lists the specific degree ranges for each direction.
POWER PER BUILDING CALCULATION
The Zonal statistics by table tool was used to calculate the power generated by the solar panels per building.
USABLE SOLAR RADIATION AND ELECTRICITY PRODUCED FOR THE STUDY AREA
The result of the zonal statistics by table was merged together with the building layer so as to be able to calculate the usable solar radiation and also the electricity that would be produced by the solar panels to the study area.
The "Add join tool" was used to achieve this aim and after which two fields were created in the Building layer's attribute table named "Usable Solar Radiation MWh" which stands for the Usable Solar Radiation in megawatts per hour and "Electricity Produced MWh" for the Electricity Produced for the study area in megawatts per hour.
Mathematical Calculation was done for each field and the map in this slide showed the result of the calculation after changing the symbology and redefine their respective classes.
By calculation, the Usable Solar Radiation = (Zonal Statistics Area * Mean of the Zonal Statistics ) / 1000 where 1000 stands for converting from kilowatt-hours per square meter to megawatt-hours per square meter.
Also by calculation, Electricity produced = the Usable Solar Radiation * 0.5 * 0.8 where 0.5 and 0.8 means 15 percent efficiency and 86 percent performance ratio respectively.
These values (0.5 and 0.8) means that the solar panels are capable of converting 15 percent of incoming solar energy into electricity, and 86 percent of that electricity is maintained throughout the installation. The attribute table below showed some of the calculated values for both calculations.
Some of the buildings (Buildings ID) with their respective values for the usable solar radiation and electricity produced.
For the Usable Solar Radiation Map, the legend showed the value ranges and the buildings having dark brown colour depicts that they are liable to use more solar radiation than other buildings while the light brown depicts the buildings with little solar radiation usage.
Same can be said to the electricity produced Map which also showed the buildings with highest electricity production in dark brown colour while the buildings with little electricity production are shown in light brown.
The electricity produced was also calculated for the entire period (one year) by adding up the total values of the electricity produced for each building. The statistics table showed the sum.
The Potential Electricity generated for the entire year
From this statistics table, it was concluded that the electricity that would be produced by the solar panels for the study area is 18,100 MWh.
This analysis has successfully helped in creating a roof cadastre for the study area and also determine the estimation of solar panel potential. The solar panel has a great potential in generating electricity over a period of time and it's hightime government looked towards this power generation which can serve as alternative from other form of power generation.
