Easy to use tool to calculate details essential to help a user analyze the solar energy available to them. It provides details of a graph of the daily energy profile over the course of a year as well as the total energy produced over that period, the optimum tilt angle and details to help users size a micro-grid. This app provides a unique feature in allowing a user to quantify the number of days annually on which they won't have enough energy to meet their load which is very useful for helping to size a micro-grid.

I am a student who has just graduated with a masters in sustainable energy engineering and a bachelors in physics both from the university of Nottingham. For my masters project I decided to try to create an easy to use programme that could help a user who doesn't have very much knowledge about solar energy implement a solar phototvoltaic system. The end result is this app, a relatively brief description for which is included below.

To calculate the energy output of the user's solar cells the programme performs a series of geometric calculations based on the earth's position with respect to the sun , the earth's rotation, etc... An integral is then solved over each hour of each day of the year to find the intensity of solar radiation incident on a horizontal plane from which the radiation on a plane tilted at any angle can be found. Data of the amount of cloud coverage and surface reflectivity corresponding to the user specified location is read in from NASA's 'POWER' website and used. Once the solar radiation has been calculated it is easy to find the energy produced using the area of the panels and efficiency of the cells and the inverter. This result is then presented to the user in the form of a graph of the daily energy over the course of a year and total energy produced for that year.

The optimum tilt angle is simply calculated by running the code described above over each tilt angle from 0 to 90 degrees and outputting the angle that corresponds to the largest annual energy generation.

The micro-grid sizing section reads in data from the NASA website of daily insolation on a horizontal surface over a 34 year period (this is why it takes a while to run). It then restructures and performs extensive statistical analysis on the data to output a table of energy deficits and the corresponding days annually on which an energy deficit of that size or larger will occur. An energy deficit is defined as the difference between the daily load and energy produced when not enough energy is generated to meet demand. The table produced is very useful for users who are users who are trying to size a micro-grid as it allows them to see the frequency with which energy deficits occur and their extent (how much energy they will lack). Thus, size their micro-grid accordingly. This is the unique component of the app.

It is also worth noting that the NASA website from which this app extracts data is in it's beta testing phase and is sometimes unavailable in which case the app will throw an error.

Lewis O'Leary
[email protected]
+44 (0)7791514094

These data were obtained from the NASA Langley Research Center POWER Project funded through the NASA Earth Science Directorate Applied Science Program.