Beyond the panels
AS I MOVE AROUND THE ISLAND and talk to people about renewable energy it has become very clear that most people only know about solar panels. The panels are the most visible as they are installed on the roof, but I believe it is important for the average citizen to understand all of the components required to power a home or a business from the sun.
Let’s start with what everyone seems to know about – the panels. The solar panels, or more accurately called Photovoltaic (PV) panels, convert sunlight into electrical energy. However, the electricity that comes from the panels is not the type of electricity we use in our homes.
It is direct current (DC), the type we get from batteries. The electricity we use in our homes is called alternating current (AC). So the panels only start the process of powering your homes.
The next component is the brain of all solar power systems and wind turbine systems as well. It is called an inverter. The inverter converts the DC to AC electricity. This process is very important and it is specific to the type of electricity that is available in your country.
Now before we go any further, it is important to understand that there are two main types of inverters – a grid-tied inverter and an off-grid inverter. Most of the companies in Barbados provide grid-tie systems.
As the name suggests, they are tied to the grid or connected to the grid. The grid is just another name for the electricity network or the cables you see on the poles throughout the island carrying electricity.
So when you are connected to the grid, it is understandable why the utility company specifies what the minimum requirements for your inverter should be.
Once you are connected – or to be more accurate inter-connected, your inverter can impact on the correct functioning of the grid. So a grid-tie system’s main components are the solar panels and the inverter. There are some other small components that are safety requirements.
There is a switch to disconnect the inverter from the grid and a switch to disconnect the panels from the inverter.
The grid-tie system allows you to sell excess electricity to the grid. So if the system produces enough energy to meet the needs in your home or business during the day, it will push the excess energy to the grid for use by other homes on the grid.
Now let’s look at an off-grid system. As the name suggests, the off-grid is not connected to the grid – well, not exactly. The more accurate thing to say would be that it is not inter-connected to the grid.
The off-grid or battery-based system uses batteries to power the system. So now they are a few more components to add to the system.
First, there are solar panels like the grid-tie system but then the panels are connected to a charge controller and the charge controller is then connected to the batteries.
The charge controller does not convert the DC electricity from the panels to AC. It regulates the DC electricity to provide the right conditions to charge the batteries. Then the inverter is connected to the batteries and converts the DC electricity from the batteries to AC electricity that you will use in your home. The off-grid system cannot sell electricity to the grid because it is not inter-connected to the grid.
The main component of an off-grid system is the panels, the charge controller, the batteries and the inverter.
Like the grid-tie system, there are several other components to meet the safety requirements. In addition to the same safety switches in the grid-tie system, the off-grid system also has a switch to disconnect the batteries.
What I have explained are the two basic types of systems, however, inverters are becoming more and more advanced. So the line between a grid-tie and off-grid system is becoming blurred. There are now hybrid inverters that can function like both grid-tie and off-grid (for more information on hybrid inverters see my BARBADOS BUSINESS AUTHORITY article of April 6, 2015). These hybrid inverters will be the future of renewable energy solutions, which will give the consumer greater flexibility in the way they use energy and interact with the utility company.
As we move into the future, the flexibility of the systems will change, the efficiency will change and the physical appearance will change, but the components that make up the system will always be required to perform the function of a solar PV system. So once you understand the basics, you would be able to understand how any system works.