Planning Solar PV System for Home and Business
When planning a Solar PV system installation for your home or business, you will need to figure out first if your desired location can accommodate the solar module array so it operates at or near its rated efficiency. Regardless of whether you wish to install the solar modules on the roof or on the ground, it is necessary to check for existing factors that will limit the power production of the system.
How to determine if your desired site can accommodate a solar PV system?
- Southern exposure.
You need enough sunlight through-out the year with little or no obstruction, in order for the solar modules to operate at their rated efficiency. This is a very important factor when installing solar system. The southern exposure is very important so your array must face south between SW (45 Degrees West) to SE (45 Degrees East). Directly South being the best possible.
- Shading.
Shading is the biggest enemy of solar power production. To benefit from 100% of the rated efficiency of the solar modules, you have to make sure that the modules will not be shadowed at any given time of the day.
The sun’s positioning is very different depending on the season and which part of Canada you are in. Also, the average of sun hours in a year varies. Let’s use Ontario as an example. In Ontario, the sun in the summer is up high and low in the winter. This factor is very important when selecting a location to install your solar pv system.
If there are any “objects” nearby the prospective location, the solar modules must be installed away from the obstruction by at least 5 times the height difference between the top of the object and the lowest module. The “object” can be anything; trees, street wires, posts or another building.
You must also consider even objects that may change and eventually shade the array, such as trees or another building. You have to remember, this is 20 year contract so you want to make sure that your system will generate the expected yearly income. A good example is a tree nearby that is not fully grown or a chance that a tall building will be built to the south of your building.
- Angle or Inclination.
Because we live in Canada, we experience all different seasons there is on the planet. The solar array MUST NOT be installed on an angle that will be efficient for only one season.
The appropriate angle of inclination of the panels when installed is related to sun’s positioning through–out the year. The relationship between the inclination or slope of the Solar PV is: “The higher the position of the sun in the sky is, the better production electricity occurs when the slope of the solar system is lower”. What about in the winter? Not to worry, as your installer it is our job to determine that the solar panels are positioned in the most efficient inclination to ensure that the solar modules will operate near at or to its peak efficiency throughout the year. An angle is chosen that is best for the full season, then it is simulated using our software package and the output is predicted. We optimize the return based on this analysis.
- Roof Area.
The roof area required depends on the system size you wished to install and the dimension of the solar PV panels used. The higher the wattage and the smaller the dimension of the panels used, the smaller the area of the roof is required. This is what the efficiency of the panel determines. The higher the panel efficiency, the more watts per square foot (meter). The roof area required is also affected by the inclination of the roof. A flat roof will require much larger area than a sloped or pitched roof to accommodate the same size system. This is due to the racking system having to hold the panels at a certain angle and then creating shadow between panel rows.
The following table shows the system size and the area required. This is based on flushed mount to a pitched roof. All sizes below have a margin of safety and can be used as a "rule of thumb".
| System Size in kW | Approximate Roof Area Required |
Number of 200W panels |
5 |
500 sq ft ( 46 sq M) |
25 |
10 |
1000 sq ft ( 92 sq M) |
50 |
50 |
5000 sq ft (464 sq M) |
250 |
100 |
10000 sq Ft (930 sq M) |
5000 |
- Ground Area.
API has two types of ground mount installations; Fixed ground mount or Single-Axis Tracker ground mount. For the ground mount installation, the same rule on installing Solar PV on the roof is applied.
Please note that there is no two systems of the same size will generate the same income per year because of the following reasons;
- - Solar systems installed in different regions with different sun hours
- - Solar systems were built using different make of Solar PV panels or different specifications
- - Solar system installed on a Tracker ground mount almost always generate greater income than a system on a ‘Pitched Fixed’ roof or ground mount as the sun hours is increased by the system tracking the sun positioning through-out the day
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