Page 262 - Solar Power in Building Design The Engineer's Complete Design Resource

232 CALIFORNIA SOLAR INITIATIVE PROGRAM

In order to complete the CSI reservation forms referenced earlier, the designer must
also determine the type, model, quantity, and efficiency of the CEC-approved inverter.
For this example let us assume that we are planning for a ground-mount solar farm
with an output capacity of 1 MW. The area available for the project is 6 acres, which
is adequate for installing a single-axis solar tracking system. Our solar power module
and inverter are chosen from approved CEC listed equipment.
Solar power system components used are:

■ PV module. SolarWorlds Powermax, 175p, unit W dc = 175, PTC = 158.3 W ac,
6680 units required.
■ Inverter. Xantrex Technology, PV225S-480P, 225 kW, efficiency 94.5 percent.

Prior to completing the CSI reservation form, the designer must use the CSI EPBB
calculator (available at www.csi-epbb.com) to determine the rebate for systems that
are smaller than 100 kW or larger. Even though BPI calculations are automatically
determined by the CSI reservation form spreadsheet, the EPBB calculation determines
a Design Factor number required by the form.

EPBB CALCULATION PROCEDURE
To conduct the EPBB calculation the designer must enter the following data in the
blank field areas:

■ Project area zip code, for example, 92596
■ Project address information
■ Customer type such as residential, commercial, government, or nonprofit
■ PV module manufacturer, model, associated module dc and PTC rating, and unit
count
■ Inverter manufacturer, model, output rating, and percent efficiency
■ Shading information, such as minimal
■ Array tilt, such as 30 degrees. For maximum efficiency the tilt angle should be close
to latitude.
■ Array azimuth in degrees, which determines orientation. For northern hemisphere
PV modules installations use 180 degrees.

After the preceding data have been entered, the CSI calculator will output the
following results:

■ Optimal tilt angle at proposed azimuth.
■ Annual kilowatt-hour output at optimal tilt facing south.
■ Summer month output from May to October.
■ CEC ac rating—a comment will indicate if the system is greater than 100 kW.
■ Design correction factor—required for calculating the CSI reservation form.
■ Geographic correction.
■ Design factor.