Before you spend any considerable cash on your solar project, it is important to evaluate whether your rooftop is fit to install and properly operate a solar energy system.
A site survey is a good starting point to assess the condition of the roof and address any issues that may affect the proposed solar power system.
The data gathered from the site survey and your energy load form the basis for the preparation of the system’s design, quotations, and the installation plan.
Surveying the site and collecting the essential information about the roof will help you plan and install your solar panels in a timely and cost-effective manner.
The various aspects you must consider when conducting a solar site survey include an assessment of:
- An appropriate location for the solar panels
- Roof Structure and Condition
- The roof’s shading during the critical solar window
- The solar panel mounting system
- The location of all the electrical components
- A suitable location to place the solar panels
Start by establishing a usable roof area that decides the maximum amount of solar panels (the power rating) that can be installed.
After selecting the location for the solar panels, make a determination whether the area of the roof is enough for the installation of adequate solar panels to power the home.
Determining the quantity of useable roof area is usually a challenge for areas that are not rectangular.
Keep in mind that you must provide access to the solar panels when planning the layout of the panels on the roof. For easiest access, just provide a walkway between rows of modules.
Also consider the structural mounting, the electrical arrangement, and routing of the cables when determining a suitable location to install the solar panels.
The main factors to consider when choosing where to install (location) rooftop solar panels are:
- The surface area of the roof
- The roof orientation for maximization of the solar energy produced
- The area shading throughout the day
- The roof structure strength and ability to support the solar panels and mounting framing.
- How the solar panels will be mounted, installed and maintained.
- The distance between the solar panels on the roof and the inverter(s)
- The risk of damage to the solar panels from falling objects, strangers and weather (wind or heavy hailstones).
- The local fire codes
A proper solar PV design is helpful in determining possible acceptable array layouts given panel and roof dimensions.
- Roof Structure and Condition
The most important factor you have to consider is the condition of the entire roof system (age, surface, type, and strength). You need to first decide if the roof structure is able to support the added weight of the solar panels and the solar mounting structures.
TIP: If in doubt about the roof’s age, surface, type, and strength, it is highly advisable to first consult a licensed roofing contractor before installing anything on your roof.
The additional loads from the solar energy system on the roof come from the Solar panels, mounting structures, installation workers and equipment, winds and other climatic loads such as hurricane and earthquakes shakings.
Generally, roofs built since the early 1980s be likely to have good roof structures that can withstand the extra weight which is about 3 and 5 pounds per square foot on the roof.
You should manually inspect the type of roof construction from the attic to determine the suitable mounting structure for the solar panels.
Some roof mounting manufacturers provide a loading analysis for their mounting structures which can help in determining the appropriate mounting for your roof.
TIP: Do not try to fabricate your own mounting frames or copy the design of a mounting system. This will, in the end, cost you much more than buying a pre-engineered structure and usually does not meet the mechanical and engineering requirements.
The solar panel mountings must be electrically connected to the building’s grounding system to conduct and ground any external surges. Special jumpers and connectors are used to ensure electrical continuity across the whole mounting.
- The roof’s shading during the critical solar window
You need to be aware that any shading on the solar panels greatly impacts their power output.
Shading is caused by obstruction of the sun shining on any part of the panels during the solar window.
Obstructions that may cause shading on the solar panels include trees, towers, power lines, and other buildings, as well as close by objects like antennas, chimneys, plumbing vents, and windows.
Shading of solar panels is also caused by accumulated dust or water on the panels’ surface.
For maximum energy production, solar panels should be located in an unshaded part of the roof especially between 9 a.m. and 3 p.m. year-round. The bulk of solar radiation and peak system output take place during this solar window.
If an unshaded location is not found, then necessary compromises such as trimming or cutting down trees may need to be made.
Even a slight shading on solar panels during peak solar window can hugely decrease the entire output of the solar panels.
A proper solar PV design incorporates a shading analysis and chooses the best roof location for solar panels for maximum system output.
- The mounting method for the array
Rooftop solar panels cannot just be placed on top of your roof without mounting structures for protection and support. The best mounting system location and approach is determined by the roof type and site location you choose.
The most common solar panel mounting systems are:
- Building Integrated mounting – solar panels are incorporated into the roofing or building exterior.
- Standoff/Flush mounting – solar panels are attached to support rails which are then fixed on the roof.
- Ballasted mounting – solar panels are fixed to the roof using a ballast load to strengthen the structure. This protects the solar panels against being carried by strong winds, hurricanes or earthquakes.
- Rack mounting – solar panels are arranged in a racking structure allowing for spacing between the racks.
- Pole mounting – solar panels are mounted on a steel pole which is normally fixed to the ground.
- Tracking mounting – solar panels are fixed on mountings that follow the sun for maximum output.
The roof age, type, and the condition usually determine the best mounting system and installation plan to use.
The main uses or advantages of solar panels mounting structures on the rooftop are:
- To structurally secure the solar panels on the roof
- To provide adequate physical protection and support to the solar panels
- To limit access to the solar panels for safety
The mounting method and layout of solar panels significantly affect the panels’ operating temperatures and how they cool naturally.
A landscape (horizontal) arrangement of the mounting is slightly better than a portrait (vertical) arrangement because the panels cool more uniformly in a horizontal arrangement.
The best solar mounting methods and structures are determined after a proper evaluation of the:
- Roof surface type, condition, and structural strength
- Roof size, slant, and orientation
- Roof height, risk of falls and safety protection methods
- Roof access during installation and maintenance
- The location of all the electrical components
The site survey must identify where all the other system components will be located.
Apart from solar panels, the other components that make up a solar power system include inverters, solar charge controller, storage batteries, dc combiners, raceways, and wiring (DC and AC cables). You must ensure that you plan and set aside an appropriate location where all these components will be installed.
The factors to consider when choosing a location for the solar inverters, charge controllers, and batteries are:
- Accessibility to the equipment for installation and servicing
- Surrounding Temperature
- Risk of damage by dust, rain and moisture, chemicals and other environmental factors
- Proximity to the main electrical board to reduce the amount of cabling, voltage drop, and installation costs.
Solar inverters, charge controllers, and batteries should be installed in weather-resistant or rain-proof spaces or indoors.
TIP: Do not install any electrical equipment in direct sunlight or areas exposed to high temperatures. Allow for adequate ventilation and cooling to the power room.
You should also make sure the electrical equipment is protected damage by pets, insects, rodents, and other pests.
Learn more about what a Proper Solar Design Can do for You Here