Karimar Ledesma Maldonado

2012 JISAO Research Experience for Undergrads

An analysis of solar radiation in the northwestern United States for photovoltaic installations

KarimarI’m from the University of Puerto Rico and I had the amazing opportunity and honor to be an intern with JISAO at the University of Washington. I spent the summer working with Laura Hinkelman and JISAO’s director, Tom Ackerman, analyzing solar radiation in the Northwestern United States.

The purpose of this research was to compare forecast model output with measured ground data, compare five-minute global horizontal irradiance (GHI) data, and understand the effect of clouds on solar radiation that reaches the earth’s surface. These measurements have a great importance to photovoltaic (PV) installation by power companies.

This research will be used in different locations of the northwestern United States for renewable energy. Five stations were analyzed for the performance of solar radiation including three in Oregon; Eugene, Burns, and Hermiston, one in Idaho; Twin Falls, and one in Montana; Dillon.

The method used was the following: In the first part of the analysis we took the hourly forecast model data for five stations from 2009 to 2011 and the hourly measured GHI for the five stations during those years. Then we calculated the differences and finally computed statistics for each year. In the second part of the analysis we took the five-minute GHI data for five stations during the years 2003 to 2011. With this data we computed the differences between consecutive five-minute averages for each year and we calculated statistics of the differences for each year. Also with this data we calculated the statistics of five-minute GHI data for each year and compared statistics from year to year.

Karimar presenting her posterOverall, based on results of statistics of the differences between the forecast model and measurement data during the years 2009 to 2011, the forecast model consistently predicts larger GHI values than are measured. Results from the second part of the analysis show that the solar radiation received in each five-minute interval has a large difference from the next interval. We can infer that we have a high standard deviation and absolute deviation because of cloud effects.

In addition to research, I had the opportunity to enjoy Seattle and the surrounding area. Seattle was definitely a new and great experience for me. First, I had the opportunity to do research which taught me so much and helped me to grow as a professional. Second, I experienced weather very different from Puerto Rico’s, and third, I had my first crazy adventure: skydiving. Fourth, I visited Mt. Rainer and I saw snow for first time, and finally, I made new good friends. I had a great time here and I am never going to forget these amazing experiences.

I’m very thankful to my mentors Laura and Tom and to the JISAO internship program. This definitely helped me to have a better idea of I want to do in my future…possibly continuing in graduate studies relate to solar radiation.


Karimar's research poster

Click on poster for full-size image [PDF]