Engr. Ajiboye Alasolewu
Roof Mount or Ground Mount? Most people choose roof mounts by default. They cost less, take less time to build, and take advantage of unused space on your property. Even though ground mounts have extra material and labor costs associated with the installation, they offer a number of benefits as well.
Building your system at ground level makes it easier to clean, maintain and replace the equipment. You also may discover that you don’t have enough space to build your system on your roof, due to obstructions, sharp angles or simply a lack of roof space. In these cases, ground mounts may be your only option.
Likewise, if you don’t have a yard (common if you live in a big city, for example) then the roof would be your only viable place to build.
Angle & Azimuth
Solar panels should point directly toward the equator for maximum exposure to the sun. If you live in northern hemisphere , you want to face your panels as close to true solar south as possible.
If you live south of the equator, face them north instead. East and west work at a reduced efficiency, if you’re building on your roof and can’t change the orientation. (Never build a system facing away from the equator. It won’t produce a significant amount of power.)
The horizontal facing (in relation to the equator) is known as the azimuth of your panels. That’s half the equation: you also have to find the right angle to tilt your panels
As a rule of thumb, you should set your panels at an angle equal to your latitude to get the most output year-round. For example, Nigeriais located at a latitude of 14.05°N. In L.A., you’ll get the most out of a system built at a 14° angle.
Throughout the year, the angle of the sun in the sky will change by about 15° in either direction. Special mounts are available to track the sun’s position throughout the year: pole mounts (which must be adjusted manually) and trackers (which follow the sun automatically).
In theory, these sound like a nice idea to squeeze a bit of extra production from your panels. In practice, they rarely make sense for residential systems because it’s almost always cheaper to buy a few extra panels to get more output. Trackers really only make sense in large-scale commercial projects when you need to squeeze every last drop of output from a large-scale system.
If at all possible, try to build your panels where they will never be covered by shade. Keep in mind that shadows grow longer in the winter, and try to anticipate how shadows from your house, trees and other obstructions will cover the area where you plan to mount your panels.
Solar panels only output their rated efficiency in full sunlight. Shade not only reduces production of the panel it touches, it can potentially hamper an entire string of panels depending on the kind of inverter you are using.
With a string inverter like the SMA Sunny Boy, if shade falls on one panel in a string, the entire string is affected. If some shade is unavoidable, though, you can turn to micro-inverters or shade optimizers to address the problem.
These systems provide shade mitigation and allow panels to produce energy independently from each other. If shade falls on a panel, the others in the string aren’t affected
Solar panels don’t require a ton of maintenance. It’s smart to clean your panels occasionally so that dust, leaves and other debris don’t impact their production.
The good news is that precipitation often takes care of this process naturally. Rain or snow will remove debris when it slides off the panels. In heavy snow regions, pole mounts are useful for lifting your system above snow banks and tilting your panels so that snow slides off naturally. In dry, dusty areas, we’d recommend wiping down and cleaning the face of the panels once a year.
In more temperate regions, once every few years is fine. This becomes more important for lower tilt angles, where debris can more easily build up and pooling water might leave spots.