Vertical or horizontal, what's the correct way to install solar panels on your roof?

Francisco CastroMay 23, 2019 29345 2

Horizontal or vertical: which is best for solar panels?

Is your roof flat or tilted? Does it face in a southern or eastern direction? Is there a tree, chimney or other structure that throws shade on it?

These and other questions must be considered when one is about to install a home solar energy system.

The contractor you hire to install the solar panels will review your energy use and recommend the correct size of your solar power system, detailing the number of photovoltaic (PV) modules to be installed and in what area of your roof.

Determining the size of the domestic solar power system should be easy enough by accessing the Hahasmart price checker. Just provide your address and your average monthly utility bill and you’ll get the actual price of solar panels and inverters - which are the most critical parts of a solar powered system - as well as provide you with an estimated cost of installation based on thousands of completed solar projects in your area. 

They’ll even provide you with an estimated buyback period, the point where the electricity savings achieved with your solar array cover the purchase of your residential solar panels and your system becomes free.

In addition, they’ll connect you with their installer network to get your residence equipped with solar power as possible.  

Computer Science major Aniruddha Joshi gives the following suggestions on an Internet message board devoted to solar energy when it comes to the actual installation.

  1. Panels should face south, assuming you are installing it in the Northern Hemisphere.
  2. Panels should be tilted at an angle with ground that equals the latitude of the location. This will help optimize energy output. However, in some cases, it may be better to install them horizontally or at some other angle for other considerations.
  3. If you are installing multiple panels in a series, all of them should be of the same rating and ideally from the same manufacturer.
  4. Panels should be installed in a shadow-free location. Having just one solar panel in the shade can stop your whole solar array from working. Also when you are installing solar panels, make sure that shade won't come with the changing of the seasons or with the future development in your neighborhood.
  5. The installation must be strong enough to sustain the maximum wind load for the given location.

The best way to deal with the installation is to hire a licensed solar energy contractor who will secure the permits from the utility and your municipality. The installer should also be familiar with the limitations on system size and grid connection. 

The installer should also recommend the best type of solar panels to meet your energy needs. There are two main types of solar panels: monocrystalline silicon solar panels and polycrystalline silicon solar panels. The main difference between the two is the color, mono (black) poly (blue). They both come in a variety of power ratings and looks. 

The entire installation process averages about two days and then you’ll need permission from the utility to turn on your domestic solar power system and start generating power on your own.

Something else to keep in mind when installing solar panels is to consider using an area of the roof where there is considerable space for the addition of more panels in the futureSolar panels are supposed to last for 25 plus years and a lot of things can happen in that time.

Horizontal or vertical

Solar panels are mounted on racking that uses the rafters in your roof as anchors. Solar installation companies mount their solar panels on rails attached to steel bolts, specifically for added security and stability. 

While most solar panels are installed horizontally, there is also valid reasons for placing them vertically, according to

  • Fewer rails are required to mount a solar panel vertically instead of horizontally. Horizontal solar panels require about twice as many railings and mountings to be installed. 
  • It is easier to have a continuous row of solar panels if they are installed vertically.
  • The size of solar panels makes them well suited to be installed vertically on most roofs.

The amount of sunlight the roof gets could also impact the direction in which they are placed. Regardless of the orientation, experts note that it is more efficient to have a consecutive block of solar panels installed using the same orientation— either vertical or horizontal. This also helps if you’re using a string inverter that connects all the panels together and send the power to a central unit. If you use microinverters that attach to each single solar panels, you have more flexibility in terms of the layout of the array.

If you live in an area with snow, your best option is to lay them horizontally because most panels are made up of two or more strings of cells that run lengthwise the module. If the panel is mounted vertically, snow will slide down, covering the bottom part of each panel, blocking some cells from all strings in that panel, thus practically killing all output. By placing them horizontally, as the snow settles on the bottom of the solar panels, it will keep the strings of solar cells that run lengthwise along the solar panel clear of snow and able to convert sunlight into energy.

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Comments (2)

  • PV Structures • December 15, 2020 1 0

    In the Southern Hemisphere we also mount the panels horizontally, however the best angle will depend on the direction on the sun. We work on commercial projects at and will create the structure that best suits the location.

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