Installing solar panels is a great way to earn money from your un-utilized roof space, while protecting the environment. But how much roof space do you need in order to install solar panels? In this post we answer this question along with a couple of others on panel orientation, tilt and roof shading.
The rule of thumb for a reinforced concrete roof (the roof typically found in most households and buildings) is that you need about 100 square feet (or 10 sq m) of space for installing 1 Kilowatt (KW) of solar capacity. So a 5 KW system would require about 500 square feet (50 sq m) of ‘shadow free’ roof space. In case you do not know the exact capacity of system required by you, you might want to refer to this post here.
How do we get to that number of 100 sq ft? Most solar panels today are in the 300-350 watt output range and thus you will require 3 panels for a 1 KW system. Each panel is roughly 20 sq ft (2 sq m) in size. Thus accommodating 3 panels will require at least 60 sq ft (6 sq m) space on your roof. In addition to the actual space occupied by the panels, we also need to leave space around the panels and their mounting structures to ensure ease of access for installation and cleaning. Additionally, in case your installation involves multiple solar panel rows, it is important to leave a gap between the rows to ensure that one set of panels does not cast a shadow on the others. this brings the total space required to the earlier mentioned 100 sq ft per KW.
In case, your installation is on a tin-shed, the shading issues no longer exist and the space required is reduced to about 80 sq ft per KW.
It is critical to ensure that the area on the roof is shadow free during the peak generation hours of 9 AM – 3 PM. This is because solar panels generate electricity using the sunlight falling on them and a shadow drastically reduces the output of the panel. Often, it is not possible to find enough area on the roof on account of shadow from things like stairwells, water tanks, trees etc. In such cases, it is still possible for you to install solar panels by using custom designed elevated structures or by installing a tin-shed on your roof so the shading is no longer a concern. The team at Earth 47 specializes in these kinds of custom installations.
It is also possible to minimize the loss due to shading through the use of advanced technologies like optimizers and micro-inverters, though this increases the system cost marginally.
India being in the northern hemisphere, the panels are installed facing South to ensure maximum generation through the day. This is because in the northern hemisphere, the sun tracks from East to West via South and South direction provides the maximum sunlight exposure. In the Southern hemisphere, solar panels are installed facing north.
However, this does not mean that panels can’t be installed facing East or West in case the conditions of your roof restrict a South facing installation. East or West facing panels will see typically see a generation loss of about 10% compared to South facing panels. Given that this is not a drastic loss, in most cases it still makes great economic sense to install solar with only a marginal increase in pay back period.
The power loss in a north facing orientation is substantially higher though and might not make economical sense.
Panels are typically installed at an angle close to the latitude of the installation site. This allows maximum amount of sunlight to hit the panels perpendicularly, thus ensuring maximum generation.
It is also possible to install panels at a tilt different from the latitude, as in the case of tin-shed installations, while suffering only a minor loss of 7-8% in generation.
In summary, it is viable in most cases to install solar panels on most roofs with the help of custom designed solutions. In case, the area available is not enough to meet 100% of your requirement, you could still offset your bill partially by utilizing the existing space optimally. After all, every rupee saved and every KG of CO2 emissions reduced count.
Reach out to Earth 47 team for a free site survey and see how much of a difference your roof can help you make to your bill today.