Stand-alone Simulation

Run the simulation.

System Setup

The first screen presented enables you to select or specify:

• A month's worth of actual data of the 60 watt module's hourly energy output - from a particular year, January 2002 to last month .
• NEW: The tilt of the array in degrees. (0 deg. is horizontal, 90 deg. is vertical).
• An array size (rating in watts peak), where "watts peak" is the power the array would produce in response to a full sun - clear day radiation directed normal to the array. Given this, the simulation will scale up (or down) the actual, 60 watt module data chosen above.
• The battery capacity (in number of days) The energy storage capacity is the product of the number of days and the daily demand.
• The battery in/out efficiency, nominally 85%
• The daily energy demand or "load" on the system (in watt hours)

Clicking on the button "Submit" will then display a new "page" with a summary of your choice of system parameters on the left and a graph to the right shoing the daily energy demand uniformly distributed over the 24 hours of a day (in red). The message "Click onthe graph below to change any hourly value" will appear.

You can then change the load profile so that it varies over the course of the day: To do this, click within the confines of the graph at any hour you wish to alter the hourly value. The daily load will change accordingly. In this, the total daily load is kept constant by decreasing the hourly load level over the other hours of the day.

Clicking on "Run Simulation" will execute the program and bring up a new page with the results.

Running the Simulation

The graph shows two things: the green bars show the daily energy, in watt-hours, produced by the array each day over the course of the selected month/year. The line shows how the state of charge of the battery changes from day to day. both for, in this case, the 31 days of the month of May,2002.

The total excess energy produced over the entire month and total deficit of energy (that which would have to be supply by a backup) is shown above the graph.

For some time periods, system output data may not be available. When this is the case, the day's array output is shown in grey. The height of the bar represents the total array output for that portion of the day for which we have data.

By clicking on any day of the month, a display of that selected day's array output and variation in SOC will be served up. (to the right).

The day plot also shows the hourly variation of the load (as you have specified) over the course of any chosen day. "Daily Excess" records the energy for that day that is not stored because the battery is fully charged.  "Daily Deficit" records the amount of energy that must be provided from a backup source to keep the system running when the battery is empty.

Note that the particular hours for which data is missing is shown, again in grey, in this plot of hourly values.

For those hours for which data is missing, the state of charge of the system is assumed to remain constant across the time interval.  Note that excess/deficit for these periods is displayed as being 0.

A record of dates when data is unavailable is kept here.

The fields on the right allow the simulation to be re-run, with different system parameters.

Run the simulation.