1) Lab Experiment Overall Goals
The overall goal of the Site Assessment for Solar Energy Utilization Experiment is to learn how to analyze solar data to assess the suitability of a site for installing a solar energy system. Different types of solar energy systems are able to collect different types of solar energy. Therefore, the DNI, GHI, and DHI solar energy should be measured as needed for the particular type of solar energy planned. For comprehensive measurements, all three types of solar energy should be measured.
2) Lab Apparatus and Equipment
a. This remote trigger experiment collects data from a pyrheliometer and two actual pyranometers installed at Amrita University, Amritapui Campus. The geographical coordinates are:
Longitude =76.492016; //units are degrees & Latitude = 9.094258; // units are degrees
b. The equipments used for this experiment include:
- Pyranometer - Huskeflux LP02-30 – receptive in the solar spectral band between 285 and 3000 nm.
- Pyrheliometer - Hukseflux DR01 - receptive in the solar spectral band between 200 and 4000 nm.
- Custom made dual axis solar tracking mechanism.
- Data Acquisition Module - Labjack UE9-Pro over Ethernet
3) Lab Procedures
a. Go to the “RT” tab in this experiment.
b. Click the “Start Streaming Live Data” button
c. Watch how the solar data changes over time. It is recommended that the user watch the data for some time, in order to see changes in the irradiation.
d. “Stop” the experiment.
e. "Export" the data as a Comma Separated Value file (.csv) to Microsoft Excel / LibreOffice / OpenSpreadsheet or a similar program, or a similar spreadsheet program.
f. If it is nighttime when you are performing the experiment, or you want to analyze a longer duration data set, Historical Data is available for download by clicking the Historical Data button.
g. After importing the data into the spreadsheet
i. Create a graph of the GHI vs. time, DHI vs. time, and DNI vs. time.
ii. Find the peak, minimum, and average Irradiance over the data file duration,
iii. Calculate the Energy received by the sensor over the duration of the data file.
To determine the Energy received by a particular sensor:
- Create a new column titled “Energy”, to the right of the column titled which you want to calculate the energy for. For example, if you want to integrate column "B", crease a new column “C”.
- Find the “Delta t”, or the interval between successive data elements. For our experiment, this is set to one second.
- In the second row of the new column, multiply the adjacent Irradiance value by one second. The formula should look something like “=B2*1”. You can copy and paste this cell into the other row elements of column “C”, down to the last row of data. Each of these energy elements approximates the solar energy received over the one second sampling interval.
- Find the Total Energy Received over the duration of the time by adding up all of the energy intervals. This can be done by using a “Sum” formula. This formula will give you the total energy received over the file duration, in units of Watt-seconds or Joules.
- Convert the Total Energy Received from Watt-seconds to Watt-hours by dividing the previous answer by 3600.
- Check your answers against the values given on the experiment webpage. If they match, Congratulations!, you have just done your first solar energy site assessment. If not, go back and check your calculations until the correct answers are obtained. Of course, for an actual site assessment, data should be collected for a much more extended duration of time.