SolarDesignTool is a Web site that allows people to design solar electric grid-tied systems online. It offers two tools for creating a photovoltaic (PV) system design:

  • The first prompts the user to supply basic design and site parameters and then generates a list of all possible system configurations for those parameters. The user can then select a few configurations, compare them, and then save one or more to a project.
  • The second allows the user to build a system design by specifying the details of each array configuration. For example, to create a system with two inverters, the user would first provide the temperature range and utility voltage. The user would then add an inverter and array, which involves selecting an inverter, module, and string configuration. The user would then repeat the process for the second inverter. The tool also allows the user to define any number of roof faces and requires that the array fit within those defined areas.

Screen Shots


photovoltaic, PV system design, grid-tie PV systems, grid-tied pv systems, string sizing, array layout design


The tool performs no energy production estimates or simulations at this time.

Expertise Required

This tool is geared toward novices and experts in the industry. The user should have some basic knowledge about designing grid-tied systems.


1000, mostly in the United States.


PV system designers, installers, integrators, and distributors and retailers of PV equipment.


1. Utility voltage
2. Sizing method (desired power output, desired output and requirement that the array fit within defined areas, largest system that will fit on roof)
3. Record low temperature and average high temperature of project site (in Celsius or Fahrenheit)
4. Output range (in Watts or kW)
5. Dimensions of roof faces (metric or English)
6. Mounting method (flush roof, tilted array, pole/ground mount)


List of all possible systems for supplied inputs. The user can select a few systems and compare the specs of those systems in a comparison table. Users with an Expert account can then save the system and view a summary report that includes:

  • Record low temperature and average high temperature of installation site
  • STC DC output of array
  • PTC DC output of array
  • CEC output of array
  • Number
  • Model names and specs for inverters and modules
  • Area of array
  • Maximum AC output current
  • Dimensions of each roof face
  • Array layout
  • Distances of each row of modules
  • Basic schematics of the roof, including length and width dimensions of the roof faces and layouts.

The report is available in HTML and PDF formats.

Computer Platform

It is an online Web application. The users do not need to install anything on their computers. The site has been tested using Google Chrome, Firefox 3.5, Internet Explorer 7 and 8, and Apple Safari. It does not work with Internet Explorer 6.

Programming Language

The Web application is written in Java, but the users do not need Java installed on their computers.


Quickly determines valid inverter module configurations and confirms whether the array will fit within the defined roof area. Paginated PDF system summary report.


The tool does not perform energy production estimates (kilowatt-hours per month or year).



Renewable Energy Design Tools, LLC


P.O. Box 833
Santa Cruz, CA 95061
United States






Free accounts can use the System Generator (the tool that generates the systems using a few basic design parameters). But free users cannot save or view generated array layouts, save designs, or generate PDFs. Expert accounts currently cost $14.95/month. Users with Expert accounts can save and edit designs, generate reports and graphics, and save a list of favorite modules and inverters. Expert users also have access to the System Builder tool.