A panel is constructed out of layers of silicon cells. These cells are made from Quartz sand. One layer of cells is positively charged and the other layer is negatively charged. These are called photovoltaic cells. Photo meaning light, and voltaic meaning volts. The generation from Solar PV panels is light generated, and not heat.
When you use the heat from the sun, this is called Solar Thermal.
When light hits the cells, it energizes the cells causing electric current to form. This electric current formed is in direct current (DC). This current is the same as the current we get from batteries.
Now that the sunlight has formed electric current to form (electricity), the direct current will need to converted into the current that homes and businesses uses. This is alternating current, or AC. For this to process to occur, you will need to have an inverter. You invert the power from DC into AC. For most homes this could be a single inverter and in commercial installations, it could be a number of inverters.
When the power has been converted (or inverted) into AC, it is distributed to the appliances inside your home.
In the case of a grid tied installation, meaning that you have grid supplied power (Eskom) and Photovoltaic power (or Solar PV), you will first utilise the power that is being generated by Solar to power you appliances and any shortfall will automatically come from the grid.
If more power is being generated than what you are able to produce then you have a couple of options;
- Throttle your generation back to just meet the usage (electrical load) or your appliances. This is done via installing a meter which can communicate the load to the inverter so that the inverter can make the necessary adjustments, OR
- You can add energy storage like Lithium Ion battery banks to store the excess energy to utilise later, OR
- You can export the excess energy storage back to the grid. Naturally, you will need to check on whether your electricity provider (municipality or Eskom), allows excess energy to be sold back into the grid.
There are two ways that your electricity provider will allow power to be exported into the grid. The one way is to give you a unit price (kWh unit). This is known as a feed-in tariff or FIT for short, OR, they will allow you to trade one unit of power for the cost of a unit of power. This is known as Net-Metering.
So in short, this is the basics of how Solar PV energy is generated from sunlight. You only need light and because we have many years of irradiance (sunlight) history, we are able to accurately predict how much energy you are able to produce in each month of the year, based on where the panels are installed. See our next blog on what can impact the performance of a Solar PV system.
If you would like to know more or a free quote on a PV Solar system, please do not hesitate to contact our office today!