Photovoltaic systems - solar panels

1. Advantages and disadvantages of photovoltaic systems

People opt for a photovoltaic energy system because it is an eco-friendly way to obtain electricity. It does not emit harmful by-products and works silently and continuously. Above all, a PV system allows the user to be independent from the national grid. Nevertheless, relying on solar energy also has its downsides – the system is relatively inefficient compared to the costs involved in setting it up.

2. When is a PV system used?

A PV system can be used for any building. However, it’s most often used for those buildings which are situated in more remote locations without access to the national grid, such as mountain chalets and holiday homes, remote hamlets, and the like.

For those buildings that are closer to the national electrical supply, a PV system is used mainly when customers want a clean and long-lasting source of energy. In such cases, buildings that use solar energy are often connected to the national power grid, too. Thus, in months with a lot of sun, unused electricity can be sold back to the power companies.

3. How does a PV cell work?

At the heart of a photovoltaic system is a solar cell, which converts photons, or particles of solar energy, into electricity. When the photons penetrate the solar cell, they push electrons from the surface back and this movement creates a flow of current. Photovoltaic cells are most often made of silicon and combined to form panels or modules. Another part of the system is a controller, which links the modules, user, and batteries together. Its role is to regulate the flow of electricity between the elements of the system.

If you want to monitor the operation of the system, an additional device is placed between the battery and the controller to show the flow between the individual elements. When a building is not connected to the public grid and is completely autonomous, a generator is added to the system. It means that, at night or when there is no sun and the cells are not generating electricity, power can still be drawn from the generator.

4. Efficiency of a photovoltaic system

Monocrystalline cells have the highest efficiency rates at 15-17.5%. Polycrystalline cells also exist, but their rate of efficiency ranges from 13-15%.

5. Calculating the size of the PV system

The size of the system is determined according to predicted usage. You need to add up all the sources of electricity in your home, including small and large appliances (each permanently connected household appliance is counted as a single source), and multiply this number by the number of hours of expected use per day. You should also remember that some devices are used during the day and some at night, so this needs to be factored into your calculations.

6. How is a PV system installed?

The place where the PV cells will be situated is of vital importance. The panels must be positioned so that they receive as much sunshine as possible:

1) solar modules should face south or as close to south as possible;

2) the modules are mounted at an angle of between 10° and 40° - during the dry season when the sun is always out, the optimal angle is 30°, while during raining or cold seasons its 70°;

3) the amount of sunshine the site gets should be as high as possible – between 7 and 18 hours a day on sunny days;

4) solar modules are mainly installed on the roof.

Modules can be mounted on adjustable stands, meaning they can move and follow the sun. Such a system is somewhat more expensive, but makes maximum use of the suns rays. Installing the PV system itself is not a complicated task. The modules are bolted to the installed substructure and connected to the transformers.

7. Subsidies for PV systems

Photovoltaic systems are considered to be long-term green investments and are therefore supported by the government. When you decide to install a PV system, the suppliers you contact will be able to explain all the details to you.

8. PV system - prices

How much does a photovoltaic system cost? The prices of PV systems can vary wildly due to the number of modules, the type of cells, and any accessories that are installed with the system. For an average family home, you will usually be looking at spending between NGN400,000 - NGN1,500,000.