Tips & Tricks - Using PVOptimize and Solar Analysis

Using the CEC NSHP Calculator (CECPV) to estimate PV production (or to test the CECPV Calculator).

Note:  The use of CECPV hourly data is an unsupported PVOptimize feature at this time.  It is also unclear how ready the CECPV calculator is ready for general use or if it will be more seamlessly integrated at some future time.

The CECPV Calculator provides a second data set of hourly data which may help in validating PV production assumptions.  It is believed that the CECPV Calculator may be better at estimating production for BIPV products.  Use of CECPV Calculator data precludes the use of some PVOptimize features and may cause unpredictable results, particularly if an attempt is made to resize the system after the CECPV data is imported.

To use CECPV data, configure a PV system using PVOptimize including selecting an inverter and modules.  Once this process is complete, save the project and reopen a second copy.

To generate CECPV data, open a copy of the CECPV Calculator (You can download a copy from the CEC website).  Enter specific configuration details, locations, azimuth, tilt, inverter and number and type of modules and calculate.

Shading - You may enter shading criteria either in the CECPV Calculator or in PVOptimize.  If you have entered shading in PVOptimize do not enter it into the calculator.  You should not use either of the extra losses either.  PVOptimize shading may also be more accurate than the CECPV  Calculator.

Once you have run the CECPV Calculator you can import the data into PVOptimize.  To import select the SystemTab in PVOptimize.  Press the Alt key in conjunction with the ‘I’ key (think alternate import).  This will open a file dialog box.  Navigate to the CECPV calculator directory and select the file ‘CECPV_output.csv’.  Note: this file is overwritten each time the calculator is run.

Compare this project with the original project.

Note: Your must use version 2 of the CECV calculator when follwoing he directions above.

Calculating PV size with multiple arrays.

This includes PV systems that have strings facing in multiple directions with different tilts or azimuths, and systems with different equipment, i.e. a 6000kW inverter and a 2500kW inverter.

To calculate sizing for multi array systems is relatively straight forward.   Time of use for both production and usage are accounted for.  This technique can consolidate as many arrays as necessary, however, it could become tedious for larger numbers.
Open a new project.  Name this project ‘Something Phase 1’. Enter customer information, utility rates, usage, etc.  Import PVWATTS data for first array, probably the most cost effective one, either production value or installation cost.  Enter inverter and modules that will be used in this array and update system size.  Enter shading data and other loss information as appropriate. Save the Phase 1 project.  Open the Phase 1 project in a second window and rename to Phase 2.

Enter from the Phase 1 Totals tab the usage amounts into the corresponding months and times in the phase 2 Usage tab.  Some of these values may be negative, They should be entered as negative. On the Phase 2 System Tab import the PVWATTS data that corresponds to the phase 2 array.  Size the system to zero the energy costs or what ever other value desired. 

This can be repeated for as many separate arrays as necessary.  The TOU use and production are correctly accounted for.

What are the heating and air conditioning columns for on the usage tab and do I need to use them?

These additional columns are for modeling in new construction.  The usage values are available on from the Title 24 Econ report.  They are included to more easily evaluate the savings that can be derived from additional energy saving measures.  They answer the question, how much to I save by increasing insulation and window quality?  The modeling can actually be done with or without solar.

The heating columns are intended for buildings using electric heat pumps.