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. This experiment will teach you how to analyze Global Horizontal Irradiance or GHI. GHI is the "global" radiation measured on a horizontal plane. It is global in the sense that it includes both direct and diffuse irradiation. As mentioned in the Theory page, GHI can be used to estimate the production of a solar PV panel.
2) Lab Apparatus and Equipment
a. This remote trigger experiment collects data from an actual pyranometer installed at Amrita University, Amritapui Campus. The geographical coordinates of the pyranometer are:
Longitude =76.492016; //units are degrees & Latitude = 9.094258; // units are degrees
b. The equipment used for this experiment include:
i. Pyranometer - Huskeflux LP02-30 – receptive in the solar spectral band between 400 and 1100 nm.
ii. 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, at least a few minutes, 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 software
i. Create a graph of the Irradiance 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.
In order to calculate the energy received by the sensor, follow the steps below:
- Create a new column titled “Energy”, to the right of the column titled “Irradiance”. This should be 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 "Delta t". The formula should look something like “=B2*1”, when Delta t = 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 sampling interval with duration Delta t.
- Find the Total Energy Received over the duration of the experiment 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.