Solar System Design

The subject of this page is mostly photovoltaic (PV) solar system, since this is the one that will make direct income in Ontario. Other technologies will be quickly touched on as well.

Producing power from solar energy currently comes out to be a little more expensive compared to other methods common in practice for the long past (e.g. fossil fuels, hydro, nuclear, and even wind). Therefore governments around the world subsidie the costs associated with renewable energy technologies such as solar, to promote green technologies and also to shift away from the traditional fossil fuels-based power production methods.

Solar systems can be stand-alone or grid-connected. In Ontario, with the government subsidy offered by the OPA, grid-connected systems are more financially viable. The FIT and microFIT programs offered by the OPA in 2009 saw dramatic spike in development of renewable energy technologies in general, and solar power in specific, in Ontario.

The starting point for designing a stand-alone system is how much power you need. For a grid-connected system the question is how much you can install (in order to maximize your income).

System Components

There are four major components in each solar system:

  • Solar panels (or some may call them solar modules)
  • Racking
  • Inverters
  • Batteries (for stand-alone systems only)

Solar Panels

Solar panels come in a variety of sizes (power output), usually in increments of 5Watts (W). For a few increments of power, panels usually come with the same dimensions. For example one manufacturer may use the same frame for panels between 230 W – 250W. This gives you some freedom in designing and maximizing your system size.  Your system size can simply be determined by multiplying the power output of your panel with the number of panels, for example:

If you have 35 of 100W panels, your PV system size is 35 x 100 = 3500W or 3.5kW.

If you know your target system size, you need to find the available PV area (the area where the solar system can be installed) before being able to choose what size of the panel you need.


Racking systems come in a variety of designs, but in general could be divided into to main categories: flat roof, and pitched roof. There are various design considerations when choosing your racking system. For a flat roof, you could use non-penetrating rackings that use ballasts to hold panels in place.


The output power of your inverter must be the same number as your contarct with the OPA. Inverter power determines the “nameplate capacity” of the system.

There are three types of inverters most commonly used in the industry:

  • micro
  • string
  • central

Each of these inverters come with their own pros and cons, and are more favorable in various situations.

For Homeowners 

Photovaltaic Systems: A Buyer’s Guide

This guide starts from scratch in explaining the application of PV systems, and teaches how to calculate the required system size for your need.

For Professionals

You will need some softwares in order to carryout your design work. As with any other engineering field, AutoCAD is a must for any design engineer. However the application of AutoCAD for solar system designers is not advanced at all.

Once you start the design work, you will need some numbers to calculate your annual system output. PVSyst is industry’ most common and most credible software. It is not a free software, and probably it is not available anywhere online, but PVSyst website.

You have a second option, a free one, that is less advanced than PVSyst. That is RETScreen that is available on Natural Resources Canada website.

Google Sketchup is not must, but quiet handy for a design engineer. This software can play a major role for presentation purposes to your clients.  Make sure you download version 7 of Google Sketchup.



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