Now that we get into renewable energy systems, let’s take a quick look at the terminology.
There are solar (or photovoltaic) cells. You typically find 60 cells on residential and 72 cells on commercial solar (or photovoltaic) modules . You can see that our Panasonic modules have 96 solar cells, which makes them a premium module. The module is the fundamental and most visible building block of a solar electric system, and is often referred to as solar panels.
When a number of modules are installed into one power generating unit, it is referred to as a solar (or photovoltaic) array.
As you can see in the pictures below, our system has modules with 96 cells each, and the array consists of 26 modules total.
The solar cells produce direct current (DC). Yet the electricity we use in our buildings is alternating current (AC). To convert the direct current into usable alternating current, we need an inverter.
The direct current from the solar array flows to the inverter, where it is changed to alternating current. The inverter is feeding into our electrical panel (or load center), from where the alternating current can power electrical loads in our home, such as the fridge, dishwasher, vacuum, lights, the TV and radio, our PC’s and laptops, etc.
If the solar array generates more power than we need in the building, it flows from the electrical panel through our smart meter back into the electrical grid. This is possible because smart meters have two channels. Channel A measures the energy flow FROM the grid. Channel B measures the flow of energy TO the grid. Using a smart meter to feed electricity back into the grid is called a grid tied system. Unlike off grid systems, we do not have to rely on batteries. The grid is in effect our battery.
For a grid tied system to operate property, we need to link our solar electric system to the grid of our electric service provider (ComEd). This process is called interconnection, and requires approval from the electrical service provider.
Once the systems are interconnected, we can receive credit for the excess electricity we generate. This credit process is called net metering, which we also need to set up with our electric service provider.
There will be more information on the details of Interconnection and net metering in an upcoming post.
In summary, the key terms to remember when talking about a solar electric system are:
- Solar cells (PV cells)
- Solar modules (PV modules)
- Solar array (PV array)
- Electrical panel (load center)
- Smart meter
- Grid tied system