Roof Top Solar Panels and Installations

Roof-top solar installations are essentially solar panels mounted on the roofs of residential or commercial buildings. As mentioned earlier, there are four ways a solar panel may be mounted (fixed rack, ground-level mounting, solar trackers and roof-top installations) and this article deals with the last kind of solar panel mounting. 

Roof-top solar panels offer three benefits to the user:

• Roof-top solar panels are an easy way to reduce your electricity bill:

Since solar energy generates savings over the long run, your energy bills will see a decline over time. Granted, the installation costs can be rather high, but once the system is up and running, solar energy is much cheaper compared to traditional energy generated by burning fossil fuels. These days, different solar energy leasing and financing schemes help reduce the initial setup cost.

• Roof-top solar panels help reduce the cooling requirement of your building:

It turns out that buildings with roof-top solar panels have cooler ceilings compared to buildings without such solar panels. This was discovered in a study by UC San Diego Jacobs School of Engineering (America). As a result, savings in energy bills are compounded.

• Roof-top solar panels can increase the retail value of your building:

A recent market study states that roof-top solar arrays can add to the value of one’s property by around 3%. Of course, this trend is more pronounced in areas where environmental conservation is a priority, because home buyers are willing to pay a premium for the cause. Read more about this here.

What are Solar Panels and How are They Mounted

Solar Panels are a collection of solar cells that convert solar radiation into electricity. Since they use photovoltaic technology, solar panels are often called ‘photovoltaic panels’ as well.

The placement and size, as well as the material, of photovoltaic solar panels determine the amount of current generated. For instance, for a given size, a solar panel located near the equator will harness a lot of sunlight compared to solar panels in the north or south poles. However, the current may be increased if the solar panel’s size is increased, and it is mounted in a way that maximizes the absorption of solar radiation.

There are four ways a photovoltaic solar panel can be mounted:

• Solar trackers – that track the sun’s movement to maximize absorption
• Fixed racks – the photovoltaic solar panel remains in one position
• Mounting at ground level – solar panels are mounted on frames that are attached to structures on the ground
• Roof-top installations – solar panels are mounted on roof tops

 The choice depends on:

• The amount of available sunlight
• Energy requirements of the home or business, and
• Size of the solar panel.

Solar Cell Inefficiencies – Why are Efficiency Levels Low?

There has been plenty of talk about high efficiency solar cells but the figure only lingers around 15-20% and when breakthroughs are mentioned, the solar module efficiency rates only go up to 50%.


Sure, these numbers get higher each year, but it will take years before they get close to 100%. There are two reasons for the poor efficiency levels of solar cells.

Firstly, Sunlight (which bumps into electrons and makes them loose to complete a circuit) is not fully absorbed by photovoltaic solar cells: 

Explanation: light is made of energies with different wavelengths (remember the 7 colors of the rainbow?) and photovoltaic material, the most common of which is silicon, can only absorb a certain range of wavelengths. As a result, the other light rays simply pass through the solar cell, and lead to losses in current production.

The problem may be fixed if a photovoltaic material with a higher absorption band is used, but this compromises the current’s strength.

Secondly, solar cells are made of semi-conductors that offer resistance to electrons:

Explanation: since silicon is a semi-conductor, it isn’t a very good means of transporting current from the circuit to the appliance. Electrons loose some of their energy as they travel across the silicon solar modules to the metallic plates placed above and below the cell to collect the current.

How Photovoltaic Solar Cells Work

We’ve previously talked about the photovoltaic effect, which is the conversion of solar radiation into electricity. Today we talk about how photovoltaic solar cells achieve this transition from light to electric power.

Solar cells are made of different types of photovoltaic material (you can read about these different types by clicking on the link) which are typically semi-conductors, such as silicon. When sunlight, or any other light for that matter, reaches these photovoltaic materials, some of the energy from the light is absorbed into the materials in the form of ‘photons’.

These photons bump into the electrons in the photovoltaic material and make them loose. These electrons then move about the solar cell and complete a circuit, which creates electricity.

Of course, one solar cell produces a tiny amount of wattage (electricity); hence, several photovoltaic solar cells are arranged in a frame or array to form a solar panel. Depending on the required power, thousands of solar panels may be placed together, such as at solar power plants; on the other hand, a small solar powered calculator can manage on a few solar cells.

The electricity is drawn away from the solar cells via metallic wires that connect to the relevant device, such as calculator, bulb, car battery, etc. The power can also be stored in batteries for later use if it’s not required immediately.

A previous blog post also covers this topic through different details.