AE 868
Commercial Solar Electric Systems

Lesson 4 Activity

Lesson 4 Activity
Activity Details

Part 1

Refer back to the scenario from the Simulation Exercise. You will have the same client in State College, PA with a 10KW system and 240V service. Given the PV module used (Trina solar TSM-250PC/PA05A), find the ambient temperature values needed for stringing the inverters for the location mentioned above, and then select your inverter as the following:
  1. Use Fronius Configuration Tool.
  2. Use ABB (formerly Power-One) to choose an inverter. (Hint: make sure to choose the right country, standards, and click “save” at each section.)
  3. Use SMA inverters (SMA America - access the stringing software) (Hint: watch the short video below for an explanation of the basic functions of Sunny Design Web to get started with the tool).

Video: Sunny Design Web - Introduction (4:12)

Sunny Design Web - Introduction
Click here for transcript of Sunny Design Web - Introduction.

PRESENTER: Welcome to Sunny Design Web. No registration is required to try out our design software. It is also possible to design PV plants without registering. Registered users benefit in many ways, however. After registering for free, you can save and manage projects, create your own PV modules and locations, as well as create your own load profiles and personalized project documentation.

For a new project, assign a project name and specify the location of the PV plant. Based on your selection, Sunny Design Web considers all settings related to the location, including system voltage and underlying legal conditions. You can review all of these settings, and adapt them as needed. Then it's time to configure the PV plant.

First, select the manufacturer and the PV module. Adjust the number of PV modules or the desired peak power. The orientation and mounting type of the PV generator can also be modified as needed. Now you can manually select the inverter, generate the design automatically, or display a list of design suggestions. Sunny Design Web takes into consideration the normative requirements at the location, such as the displacement power factor. A suggestion is computed.

In addition, Sunny Design Web offers the option of restricting the choice of inverters or sorting them by various criteria. The desired design can now be selected and then adopted with a click on the lower right. In the inverter details, you can see at a glance how the PV modules are connected to the inverter, as well as the detailed inverter configuration.

In the next step, you determine the optimal cable dimension from the desired cable length, the cross-section, and the desired DC and AC cable material. Sunny Design Web recommends the minimum required cable cross-section. After dimensioning the cable, continue with determining your possible self-consumption.

You can estimate your possible self-consumption of the generated PV energy with just a few clicks. For this, you merely need to select a load profile and the annual energy demand. To optimize self-consumption, Sunny Design Web also takes the integration of battery storage systems into consideration. In the Results Report, you can see, among other things, the possible self-consumption quota, both with and without optimization via energy storage. The overview summarizes, once again, entries, results, and current information on the PV plant.

All result values are displayed in compact form under Results. To print project documentation or output it as a PDF file, simply click on Document and Output Format under Settings. Choose the desired documents and paper size, and simply click on Download Project Documentation. The selected combination will be displayed accordingly in the preview. This completes the plant design.

Credit: SMA Solar Technology

For each of the three options for Part 1, gather the following information in a Word document. Label this section as "Part 1." You will combine this with Part 2 for a report.

  • Generate a PDF report from each stringing tool.
  • In a Word document, answer the following questions for Part 1:
    • What is the capacity factor, or utilization factor, (Power PV/Power inverter) for each choice?
    • How many inverters did you have to use to string the entire 10KW PV array? Why?
    • What is the best stringing for this system? What is the inverter used?

Part 2

For the same client in State College, PA who wants to install 10 kW using the same PV module from Part 1, you are to come up with the estimated annual energy yield (inverters are considered at this time).
  1. In SAM, choose the right PV module, system configuration (series/parallel), and simulate the effect of choosing different inverters for the same location.
  2. Go to the NREL PVWatt website, try to choose the same values for the system size, tilt, and azimuth angles for the same location, and simulate the energy production and compare with SAM.
In the same Word document used for Part 1, gather the following information. Label this section as "Part 2." You will be combining this information with that of Part 1 for your Lesson 4 Activity submission.
  • Prepare a report showing both simulation results for SAM and PVWatt and indicate the difference in annual energy productions. (Hint: we learned about how inverter efficiency and capacity factor affect annual production.)
  • Answer the question: Does inverter selection depend on the PV module used? Explain why.


Prepare a report with Part 1 and Part 2 for submission. The report is to be no more than two double-spaced pages in a 12 point font.

Bonus: Build your own Excel calculator for Inverter stringing given the PV module parameters. (Hint: use NOCT calculated from the Lesson 2 Activity Bonus Question).

Submission Instructions and Grading Please visit the Lesson Activity page for submission instructions and grading information.