How do I know where to position solar panels on my roof?
The amount of solar energy that the earth receives on a daily basis is far more than the total energy than what we need – as a matter of fact – almost 6 000 times more. The sun is a powerful source of energy. The picture below indicates the size of the sun compared to earth, what more do we need to say about this source of power for our earth?
Southern Africa is swathed in a solar resource easily available and is perhaps the highest in the world enjoying sunshine almost all year round. Thus providing South Africa with excellent radiation for renewable energy. The solar radiance levels, particularly those in the Northern Cape and the North-West Province are exceptional, which means that the strength of the solar power received in South Africa is phenomenal compared to other counties in the Northern Hemisphere.
Needless to say South Africa is geographically well-placed to make use of this free and reliable source of energy which the sun has to offer day in and day out.
This leads one to the question:
How do I know where to place solar panels [modules] on my roof?
South Africa is in the Southern Hemisphere. Therefore True North is the most efficient direction solar panels must face to obtain the best all year round optimum radiation from the sun. The sun is higher in the sky in summer, almost directly above as can be seen from the diagram below.
Where as in winter the sun is at a lower angle as can be seen from this diagram.
So the big question is: “What do you do if you don’t have a North facing Roof?” If you have a South facing roof unfortunately a roof option won’t work. Don’t despair we can look at a ground mounting solution. Solar Carports serve the dual function of creating shade for vehicles in a parking area and simultaneously providing an area for the solar modules to be mounted upon.
On farms or when there is open space, a ground mounted solution will eliminate the incorrect roof orientation. The examples below are some of the solutions we offer our clients.
Another option is an East/West orientation. In Cape Town, during summer we have early sunrises at 6.00 am and late sunsets at 8.00 pm which are great but in winter it will be less efficient.
From the graph below one can see although East/West is efficient in summer overall a true North is actually the most efficient orientation for a solar module in the Sothern Hemisphere.
Therefore when you purchase a new home ensure the roof orientation is true north and there is sufficient roof space, approximately 20 m² should be sufficient for most solar systems.
How do I know if my roof structure is strong enough for the weight of solar modules?
If your rafters are at a maximum of 1 meter apart and the structural integrity of the roof design is solid. Our installers will immediately on site be able to ascertain if a residential home roof is strong enough to hold the weight from a solar array.
The local municipalities do not require any plans for the solar panels to be installed on a roof, provided they are installed directly onto the roof without infringing on any height restrictions.
Business Owners what you need to negotiate prior to signing that lease contract.
Business owners before you sign a lease include in writing from the future landlord that permission will be granted to install solar panels on their roof. Also ensure a structural engineer approves the roof structure to be able to withhold 20 kilograms per 1,5 meters squared. This will give you the knowledge upfront to know if solar panels can be installed on the roof.