When determining if a solar photovoltaic (PV) system is a good fit for your building, there are a lot of important items to consider. Read the sections below for more information.

The first place you should consider installing solar on your property is the rooftop of your building. As a starting point for evaluating your roof, visit the SolarTO Map.

A number of factors must be considered when evaluating a solar energy system for your roof.

Age & condition of your roof

It is not recommended to install solar on a roof that is more than 10 years old (dependent on condition). If the roof will need to be replaced soon, it is best to re-roof and install solar at the same time or shortly after in order to avoid the cost of removing the panels, replacing the roof, and then reconnecting the solar installation.

Will the solar installer make holes in my roof?

Installers typically penetrate sloped roofs roof with bolts to secure the solar panel racking system in place. To prevent water from leaking, the bolt fixtures are surrounded by flashing, which is an aluminum or plastic shield that fits under the existing roofing material.

Most solar installations on flat roofs do not require penetrations. The panels and racking system are simply ‘ballasted’ which mean that they are weighed down with concrete blocks to secure the panels to the roof.

Roof warranty

If you are concerned about the solar installation impacting your roof warranty, refer to the terms and conditions in your roof warranty documents and contact your roofing company to discuss what is needed to keep the warranty intact. Solar panels can actually protect and extend the life of your roof by shielding the roof from the elements (wind, rain, and snow).

Can my roof handle the weight of the solar panels?

Installing solar panels add additional weight to your roof. On average solar installations weigh two to four pounds per square foot, which is usually within the acceptable limit of most roofs. Ballasted systems on flat roofs add more load. To avoid any structural problems it is critical to have a professional conduct a structural analysis of your roof. A structural review is required as part of the building permit process in Toronto.

Roof size

The average size of a solar panel used for a rooftop solar installation is approximately 20 square feet. Most solar panels today are in the 300 to 450 watt output range, which means that you will require three panels for a one kW system. Additional space is required for mounting structures. So, an average five kW system would roughly take up 500 square feet of roof space.

If you have limited useable roof space, you can opt for higher wattage solar panels to maximize electricity generation in a small area.

Roof slope & direction

Solar systems installed on a sloped roof are typically flush mounted to follow the slope of the roof. An angle between 10 and 45 degrees works well for most solar installations. On a flat roof, the solar panels can be tilted to optimize energy production.

In the Northern hemisphere (as is the City of Toronto), the optimal orientation for solar panels is on a south-facing roof. East/west-facing sloped roofs also work but result in an average of 15 per cent less output in comparison.

Obstructions & shading

Some areas of your roof may not be ideal for solar due to shading from nearby trees and or tall buildings. Smaller amounts of shading can be addressed by installing micro-inverters or power optimizers to enhance system performance.

Obstructions including chimneys, skylights and vents, cannot have solar panels installed over them. If obstructions are limiting your usable roof space, you can opt for higher wattage panels.

Wall-mounted solar

South-facing walls can provide suitable surfaces for solar mounting provided they are not shaded by surrounding objects. Wall-mounted panels should be located high on building walls to reduce the potential for damage and shading. The solar panels can also be tilted off the wall to function as an awning to shade windows and doors located below the panels.

Building Integrated Photovoltaics (BIPV)

Building Integrated Photovoltaics (BIPV) is a technology that integrates solar power generation into the building envelope: roofs (e.g. solar shingles, tiles, and skylights), façade (cladding, curtain wall, windows) or external building systems balcony railings and shade structures). BIPV can be installed during the construction phase of a building or deployed as part of a retrofit in an existing building when the replacement of building envelope components is required. To learn more about BIPV refer to National Resources Canada’s (NRCAN) website.

Solar mounted on adjacent structures

You can also install solar on adjacent structures such as a detached garage, shed, or a leisure shelter. The roof of the house should always be considered before adjacent structures due to proximity of the electrical panel and ease of connection. Solar feasibility for adjacent structures is dependent on their structural integrity and the availability of an existing electricity run.

Solar canopies

A solar canopy is an outdoor structure with solar panels attached. Solar canopies such as solar carports provide shade for cars, and can integrate electric vehicle charging stations. Solar can also be integrated into patio covers, awnings, and gazebos. Solar canopies are more costly than regular rooftop systems, but they make use of otherwise underutilized space.

Ground-mounted solar

Although more expensive, a ground-mounted system can be positioned to face due south and the angle can be set to optimize electricity production. Before considering a ground-mounted system, we recommend that you check regulations governing their design requirements and acceptability for your site.

Solar energy output depends on the level of direct sunlight reaching the panels. Shading can drastically reduce solar energy output. Shading can be caused by the features of the building itself like plumbing stacks, roof vents and chimneys or external factors like nearby buildings and trees.

Shading from trees

Nearby trees can prevent direct sunlight from reaching the solar panels on your property. You may be able to prune several branches before installing solar on your property but removing trees is not advisable as they provide their own benefits to you and your neighborhood. For more information regarding removing trees on private property visit the City’s Permit to Remove or Injure Trees website or contact 311. It is important to also consider the projected growth of vegetation at the design stage of the solar system, particularly in the case of ground-mounted systems.

Shading from tall buildings & new construction

There are no by-laws protecting ‘Right to Light’ in Toronto. If you are concerned about shading impacts from new developments around your property, we recommend you review Toronto’s Official Plan for policies and zoning information on surrounding properties to help you assess the risk of a future shadow impact. You can also use the city-wide zoning maps to find the zoning on a property.

25 years is the standard time period for most solar panel electricity production guarantees provided by the manufacturer, but the useful service life of solar panels can easily exceed 30 to 40 years. Solar panels lose some capacity for energy production over their lifespan due to the following factors:


Solar panels slowly degrade over time, which means they produce slightly less electricity from the same amount of sunlight. On average, solar panels have a degradation rate of about 0.5 per cent per year which means that they will operate at 91 per cent of their original efficiency after 20 years, and about 82 per cent after 40 years.

Soiling from dust & grime

Dust and particulate matter buildup on the surface of the panels can reduce energy output, so panels should be cleaned periodically. Avoid climbing on the roof for safety reasons; a hose and nozzle from ground level should work for washing.

Cloudy & snowy weather

Solar panels still produce electricity when clouds are present, but they will produce less energy than they would on a sunny day. Snow cover blocks sunlight from reaching the solar panels. Most panels are installed on a slope, so snow slips off easily once the sun comes out and the panels warm up.


Solar panels require minimal maintenance as they have no moving parts. Maintenance for residential solar panels is straightforward: wash the panels periodically, trim nearby tree branches if needed and remove snow from the surface of the panels with a broom if it’s safe to do so. Snow will slide off by itself once the sun comes out and the modules warm up. Many companies offer panel cleaning services.

The solar installation’s connection components and inverters can benefit from professional preventative maintenance inspections.  When selecting a solar installer, ensure they provide a minimum one year workmanship warranty (see warranty section below). You can also pay your contractor to rectify any problems on an as-needed basis.  If you purchase a service agreement, it should include regular observation of your system via remote access, and annual site visits to check components, retighten bolts, test connectors and perform scheduled cleaning.


A monitoring system provides real-time information about your solar system’s performance and provides a notification if there is an issue. If your monitoring software relies on the internet, try to maintain a consistent internet connection to ensure a complete data set.

As a solar system owner, it is advised that you verify your solar electricity generation numbers regularly by checking your monitoring interface and phone app, and your monthly Toronto Hydro bill if your system is connected to the grid. If you notice any abnormalities, contact your solar installer or a trusted solar maintenance provider.

Larger commercial and industrial systems typically require more detailed maintenance and monitoring, which includes performance monitoring and diagnostics, energy forecasting, and preventative or condition-based maintenance, in addition to cleaning the panels and vegetation control.

A few warranties are available for solar panels, equipment and installation:

Equipment warranties

  • Solar panel warranty
    • The performance warranty will typically guarantee a minimum of 80 per cent of the initial energy production at 25 years. If your solar panels degrade faster than the warranty indicates, the manufacturer will either repair the panel or replace it.
    • The equipment warranty will typically guarantee 10 to 12 years without failing. The equipment warranty should protect you against premature wear and tear, manufacturing defects, etc.
  • Inverter warranty
    • The warranty for your inverters will depend on the manufacturer. Standard “string inverters”, which handle power from a “string” of panels, are usually warrantied for a period ranging from five to 12 years. “Micro-inverters”, which attach to each individual panel, have warranties for up to 20 to 25 years. Inverter warranties generally cover material or manufacturing defects; while they likely won’t cover improper installations, normal wear and tear caused by weather conditions, and improper maintenance.
  • Racking warranty
    • Most racking or mounting equipment come with a 10 to 20 year manufacturer’s warranty on material defects. The manufacturer may choose to repair or replace a defective product in the case of a warranty claim.

Installation/workmanship warranty

Where equipment warranties protect you against component-related issues, the workmanship warranty protects you against labour-related defects arising from improper installation. These warranties cover things like labour, electrical work, roof penetrations, etc. Solar workmanship warranties vary depending on the installer. Some companies don’t offer a warranty, while others provide two to five years of coverage.

Is solar a good investment?

Whether you are a homeowner or a business, electricity costs can make up a large chunk of your monthly expenses. Solar allows you to reduce your electricity bills by generating a portion of your own electricity. Most solar panel manufacturers feature a 25-year output warranty, but panels can continue to generate electricity for over 30 years.

The price of electricity in Ontario has risen by five to seven per cent annually over the past decade. By producing a portion of your own electricity with solar, you can protect yourself against rising electricity costs and make your monthly bills more predictable.

Cost of a solar PV system

Dollars per watt ($/watt) is the price you pay for every watt of solar being installed.  It is calculated by dividing the total cost by the solar system capacity. $/watt is the most useful metric for comparing multiple vendor quotes as it allows for an apples-to-apples comparison of quotes that may vary in total wattage, selected equipment, layout, etc. Generally, a low $/watt value is considered favourable while a high $/watt is considered unfavourable (assuming a basic solar installation, price will increase with the integration of premium equipment and complicated designs). The $/watt of the solar system should decrease as the size increases due to economies of scale in solar contracting.

How much can you save with solar?

Grid-connected solar energy systems create savings by offsetting costs on your monthly electricity bill. For example, the Toronto Hydro ‘Time of Use’ rate averages about $0.156/kWh, so you save this amount with each kWh generated by your solar panels. A typical five kW system generates about 5,750 kWh per year, meaning you could rough save $900 annually.

Another way that solar panels create savings is through incentives such as grants and tax credits. The right mix of utility bill savings and incentives make solar an attractive investment.

Solar savings depend on the size of the system, the percentage of energy you are looking to offset, annual electrical usage and your energy habits, electricity rates, and your chosen financing option.

What is the average payback?

The payback period is the length of time (measured in years) that it will take for the savings generated by your solar panels to equal the initial capital cost. The average payback period for a residential grid-tied system is about nine to 11 years, without considering any incentives.

The payback period can vary by several years depending on your location, sun exposure, shade from trees/buildings, and the orientation/slope of your roof, electricity rate (time of use or tiered), your annual electrical usage and the financing option that you choose.

See financing, grants and incentives available that can help off-set costs.

It is important to understand the energy consumption of your property as it plays the most important role in determining the appropriate size of the solar system or limitations on the size of the system. Your solar system will need to be connected to Toronto Hydro’s electricity grid to qualify for Net Metering, which allows excess energy generated by your system to be sent back to the grid in exchange for credits on your electricity bill.

As part of their proposal/design, your solar installer should measure your current energy use in order to properly size your solar generation capacity to align with your needs. Your solar installer should ensure that the solar generation does not exceed your consumption.

The way Toronto Hydro’s Net Metering program works is that any excess electricity generated will be exported to the grid in exchange for a credit on your electricity bill (to be used when your system is not generating as much energy). These credits are only valid for 12 months, so there is no benefit to generating more electricity than your home/building uses on an annual basis. For more information about the Net Metering program, visit the Net Metering – Toronto Hydro webpage.

How do I measure my electricity use?

The best way to find out how much electricity you consume and how much you pay is to review your Toronto Hydro bill. You can add up your usage (in kWh) over 12 months to see how much electricity used in a year.

The payback period for solar will vary depending on your electricity rate (time of use, tiered/fixed, or SPOT). The Ontario Energy Board (OEB) website explains how to read your electricity bill. For more information, visit the OEB’s Understanding your electricity bill webpage.

Prior to installing solar, consider whether you plan on making any changes that will change your electricity use like an addition/major renovation for your home, buying an electric vehicle and charging it on-site, upgrading your HVAC system, or investing in improving your energy efficiency. For example, if you drive an electric car 25,000km/year and charge almost exclusively at home this could add up to 4,000kWh/year to your electricity usage.

These plans should be discussed with your installer in advance so they can account for your future electricity needs while designing your solar system.

I just moved into my home – how do I measure my energy use?

If you don’t have a full year of electricity consumption data, your installer should be able to roughly estimate your annual consumption. Provide them with as much information as possible to help them with their estimate. If you have not yet moved into your new building or moved into a building that has undergone major renovation, you would need to consult an electrician for your electrical load forecast.

Investigate your building’s energy efficiency

Before going solar, it is recommended that you investigate potential energy efficiency upgrades in order to reduce your electricity demand. This can include low-cost and easy-to-implement  measures such as switching to LED lighting, replacing windows and adding insulation. By reducing your electricity demand, you will decrease the number of solar panels required to meet your needs, bringing down the capital cost of your system.

We recommend starting with an energy audit, which will help you understand where your property is losing energy and the steps you can take to improve the efficiency of your building.

The City offers resources to help with your energy improvement decisions. Refer to Energy Efficiency Incentives for Homeowners to explore options. Businesses/building owners can refer to the Better Buildings Navigation & Support Services for details.

Electricity bills after solar

How much money can I save on my electricity bill by installing solar?

Solar panels will generate savings by offsetting the cost of electricity that you would otherwise be paying for from the grid. Any excess solar electricity that is exported to the grid will earn you a credit on your bill to be used later on when your panels are not producing as much.

For example, the Toronto Hydro Time of Use rate currently averages $0.1565 per kWh, so this is roughly how much you will save for each kWh your solar panels generate. A typical five kW solar system generates about 5,750 kWh of electricity per year, which means that you could save approximately $900 annually. Savings will depend on the size of the system, annual electricity usage, electricity rates and your chosen financing method.

Will I receive an electricity bill if I have solar panels?

Unless your solar energy system includes battery storage, and you are disconnected from the electricity grid (very rare in Toronto), you will continue to receive a monthly electricity bill. However, solar panels will allow you to drastically reduce your bill with a solar system that matches your energy consumption. Administrative fees on your Toronto Hydro bill, such as the delivery charges, will still apply.

Planning for the installation of solar when designing a building

When solar design is not considered in the early stages of construction/renovation of a building, it may become technically or financially unfeasible to install solar. If you have future plans to go solar, discuss ‘solar ready’ design considerations with your contractor/electrician so they can support your goals.

Solar ready design includes considerations and modifications that can be made to new buildings and buildings undergoing substantial renovation, to facilitate and optimize the installation of a future solar energy system,  For example, solar-ready design guidelines include adding an extra electrical conduit (1/2 to ¾ inch) from the main electrical panel to the roof while the walls are open, and to locate any roof obstructions like roof vents, plumbing stack and skylights on the north side of the roof to avoid future shading.

We recommend you review the following resources and share these with your builder/architect/renovator.

  • Natural Resources Canada (NRCAN) produced a Solar Ready Guidelines document, which specifies a number of design considerations builders can implement in new building to prepare for the installation of a future solar photovoltaic or solar thermal systems.
  • The Photovoltaic (PV) Ready Guidelines, also created by NRCAN, describe design considerations and specify modifications builders can make to new attached and detached homes in preparation for the installation of a future large array photovoltaic system. The PV Ready Guidelines are intended for large array PV systems (e.g., as would be the case in near net zero or net zero energy home designs). The Solar Ready Guidelines are intended for solar thermal and small array PV systems.
  • Natural Resources Canada (NRCAN) produced the Planning & Decision Guide for Solar PV systems to provide solar consultants, home owners, home builders, and their design and construction teams with a framework for making decisions on the types of solar PV systems to use in residential building projects.
  • Planning and Decision Guide for Solar PV Systems Webinar: This webinar by the Canadian Renewable Energy Association (CanREA) demonstrates the use of the Planning & Decision Guide.

Solar can meet a portion of the building’s electricity needs, offset electricity usage in common areas and provide clean power for electric vehicle charging. The logistics of installing solar for a multi-unit building are more complicated.

Is the building’s roof suitable for solar?

Consider the age and condition of the roof. Installing solar on a roof that is older than ten years is not advised. To determine the remaining lifespan of the roof and the schedule for roof replacement or major repairs, you could access the reserve study (evaluation of a property’s physical components), your building’s maintenance records or consult a qualified roofer or professional engineer.

Roof obstructions such as mechanical equipment, can limit space for solar. In this case, a solar canopy, which raises the array above the obstructions, can be considered but is complex and costly.

If you determine that the building’s roof is not a good fit for solar, consider:

  • Other parts of the property such as a parking lot or garage
  • A ground-mounted solar system (less optimal in dense neighbourhoods)
  • Building Integrated Photovoltaics (BIPV) to make use of vertical space (better suited for new construction)
  • Focusing your efforts on other energy efficiency upgrades

Configuration of the building’s electric metering

The size of the solar system for a multiunit building can also depend on how the building is metered. Metering types include:

  • Bulk-metered: multiple units are billed through one master meter
  • Sub-metered: one master meter, but the consumption of each unit is determined by apportioning the bulk bill by sub-metering
  • Suite-metered: each unit is individually metered by the utility, with a separate meter for common areas

Toronto Hydro’s Net Metering program only allows for one application per meter and does not allow meter aggregation. To connect solar to multiple meters, a separate application will be required for each meter. Typically, the easiest option in a multi-unit building is to connect to the meter servicing common areas. For both bulk- and sub-metered buildings, the solar system can be connected to the master meter to offset common and individual electricity consumption. Since systems are sized to meet electricity consumption, master metering allows for a larger solar system.

Financial considerations

Taller buildings typically have a smaller rooftop area, so solar will only cover a small percentage of the building’s total electricity needs. There are also extra costs for lifting panels to the roof, racking due to higher wind loads and extended electrical runs. Ensure your solar installer is experienced with taller buildings.

A project that offsets the electricity usage in the building’s common areas will still benefit all residents and the cost of the solar system can be factored into maintenance fees or the condominium association can use reserve funds to finance the project.

It is also important to consider the rate classification (Time of Use, Tiered or SPOT), that applies to the meter connected to the solar system. The electricity rate will impact the payback period, but the solar installer will help determine the optimal solution to maximize your return on investment.

The City of Toronto offers many grants and incentives including the Energy Retrofit Loan program to help multi-unit buildings invest in energy improvements.

Decision-making considerations

You might have ownership for part of the roof but in most cases the roof space is considered a common resource. Find out who has controlling rights to the roof space and whose permission will be required. To ensure all relevant legal factors are considered, check applicable by-laws and declarations. The solar system must be connected to at least one meter, so the chosen meter(s) and their account holder(s) must be decided.

You will also need buy-in from the governing body and those who control the building’s financial decisions.

If you are exploring options in the capacity of a unit owner, you can submit your proposal for solar to the condominium board. The proposal should explain the scope, economic analysis including cost, incentives, financing and any foreseeable legal issues or other concerns. You can also present a preliminary proposal provided by a solar installer.

Refer to our Solar Directory to find installers that have experience installing solar in multi-unit buildings.

It is important to hire a qualified installer for the following reasons:

  • There are a lot of safety hazards associated with the installation of solar panels, including risk of electric shock, slip and fall accidents and muscle injuries.
  • You can cut costs by buying through an installer. Solar installers buy equipment in bulk from distributors and pass the savings on to the customer.
  • Installing solar panels is not an easy process. Solar installations involve creating construction plans, purchasing and safely storing equipment, installing the mounting system, applying for utility interconnection and building permits, required inspections, insurance, etc.
  • Wiring and electrical connection of your solar system must be completed by an Electrical Contractor licensed by the Electrical Safety Authority (ESA) in Ontario. It may also be required to qualify for rebates and grants.
  • Many solar equipment manufacturers will only honor their warranties if a professional installer installs their equipment. Also, installers often offer an additional workmanship warranty.
  • The installation process may require drilling into your roof. Drilling in the wrong spots can create structural issues and improper sealing and flashing can cause roof leaks, which can lead to interior water damage and mold growth.