Anatomy of a Commercial Solar Photovoltaic System

The iconic photovoltaic (PV) panel is arguably the most recognizable symbol of renewable energy worldwide.  Photovoltaic panels work by turning the energy of sunlight into DC electricity through a process known as the photoelectric effect.

Each PV panel is actually made up of a multitude of smaller PV cells which combine their individual small electric outputs into a larger output on each panel.  The electric output of each panel is then combined with the outputs of the other PV panels to produce a large system-wide output.

The number of panels used in any given solar electric system will depend on a number of factors such as available roof space and size of the grid connection to the building.  Under the Nova Scotia Power Enhanced Metering program, the number of panels you can put up is limited based on your building's electricity consumption because solar installations must produce less electricity than your building consumes on a yearly basis.

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The racking system  is the structure on which the PV panels are mounted.  Depending on the scenario, the racking system also serves to tilt up the PV array towards the south, and can even allow the PV array to track the sun throughout the day.  

For commercial installations, the racking system typically consists of multiple rows of footings and rails that get structurally mounted to the roof of the building, or are held down by virtue of weighted ballasts integral to the racking itself.

The rails are bolted to the footings, and provide the structural base upon which the PV panels are mounted.  For safety purposes, each rail is electrically grounded to mitigate lighting strike and electrical fault hazards.

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Maintaining a watertight roof barrier is one of the most crucial factors in extending the lifetime of a building.  That's why Doctor Solar offers solar PV systems that require zero roof penetrations, thereby elminating the possibility of compromising roof moisture integrity.

Our ballasted PV arrays allow us to secure the panels to your roof by virtue of counterweights that are installed into the structure of the racking system.  Ballasted PV array designs work best with commercial roofing that can sustain the extra weight of the ballasts.

Because the racking system in not fastened to the roof, wind loading on the PV array must be taken into careful consideration.  This means that the PV panels can only be mounted at angles within 10º of horizontal, which reduces the available solar resource that the array sees.

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A string inverter is a device that takes a high voltage DC output of an entire PV array and turns it into usable AC Power.  For commercial installations this is usually either 240V single phase or three phase.

  • Lower up-front cost compared to micro-inverters
  • Output less power than an equivalent system using micro-inverters
  • Less reliable, since problems tend to propagate throughout the system instead of remaining isolated
  • Can't monitor the output or status of individual PV panels, only the entire system output
  • Can't add additional panels in the future.  Removing existing panels affects performance of remaining panels.
  • More stringent regulations under the Canadian Electrical Code due to dangerous high-voltage DC line run
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A micro-inverter is a small device designed to inverter the DC power produced by an individual PV panel into usable AC power.  In other words, a ten panel system would have ten micro-inverters.  Each micro-inverter detects how much DC power that a particular panel is producing, allowing it to draw the optimum amount of electric current from that panel through a process known as maximum power-point tracking.

  • Higher up-front costs than an equivalent system using string inverter topology
  • Allows the PV array to output the maximum possible power, regardless of shading on or problems with individual panels
  • More reliable since any fault within the system remains isolated from the rest of the system, allowing it to keep running
  • Each PV panel's output can be monitored independently of the other panels, making faults extremely easily to track down
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The line run is the part of the system that brings the electricity from the roof into your building's electrical breaker panel.

The line run consists of a cable that gets installed inside and outside your building.  The cable itself features several layers of protection including an inner electrical insulator, steel shielding, and an external waterproof membrane.  For installations using a string inverter topology, the line run is subject to additional regulatory requirements under the Canadian Electircal Code.

For safety reasons, the cable is connected to an electrical disconnect box before being wired into your home's electrical circuit-breaker panel.

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We're the solar experts

We've been installing solar panels in Nova Scotia for decades, so we know a thing or two about how to get the job done. As the primary installation company under the Halifax Solar City program, we have been installing literally hundreds of solar systems each year. We are fully certified through the Nova Scotia Construction Safety Association, and take pride in providing a full solar system solution to homeowners; from permitting and design, to installation and maintenance.

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Monitor your system in real time

With Doctor Solar's standard micro-inverter monitoring system, you can see exactly how well your photovoltaic array is performing in real time. Because each PV panel has its own dedicated inverter, you can see excatly how much power each panel in your array is producing!  Just log in to your monitoring system web page for useful insights into your solar system, including how much money you've made. Best of all, Doctor Solar will automatically receive an email if there are any problems with your system!