In Part 3A of this series, we’ll discuss the second type of system used to produce solar power, the grid-tied system with battery backup. Here we’ll cover the components from the PV panels to the battery bank and associated items.
Grid-tied – A Definition
This was covered previously in Part 2 of this series, but, briefly, to recap, a grid-tied solar power system produces electricity that is fed into the utility grid, and then, from the grid, back into the home.
The advantage of adding a battery as a backup is that, should there be a blackout or loss of power from the grid, the electricity stored in the battery can be used to keep your household running. Which means you’ll be able to eat – great! The downside is that this type of system is significantly more expensive due to the additional components required.
Components Of A Grid-Tied Solar Electric System With Battery Backup
1. Solar Panels
The solar panel, which goes by a variety of epithets, including solar module or photovoltaic (PV) panel, is where the whole process of turning solar energy into usable electricity begins. A single panel consists of a number of cells that contain silicon, and these react with the sunlight to produce DC (direct current) electricity.
In order to run appliances within the home, several panels will be needed to produce enough solar electrical power. These panels will be joined together to form an array.
2. Mounting Racks
Having determined how many solar panels will be needed to cover a home’s solar power requirements, the next thing to work out is where to put them and how. The “where” can be either on the roof (the most common option), on poles set in concrete or on the ground. The “how” is where mounting racks come in. Mounting racks are used to secure and orientate the PV panels (south-facing is generally best as far as the amount of available sunlight is concerned).
3. DC Disconnect
If a current overload was to occur, the array DC disconnect would enable you to safely interrupt the electrical flow from the solar panels.
4. Charge Controller
If you’re using a system with a battery back-up, a charge controller is a necessity. It regulates the amount of power flowing to and from the battery, and prevents overcharging, and, if it has a low-voltage disconnect, over-discharging, both of which can seriously damage the battery. The moral to this story – be nice to your battery, and your battery will be nice to you! Hence, the need for a charge controller – it’s like your battery’s Mum!
5. Battery Bank
A battery bank stores electricity from the PV panels for use in case of a blackout. There are several different types of batteries available, but the one that’s best for grid-tied systems is the sealed absorbent glass mat (or AGM), which requires no maintenance (=potentially less headaches!) and is designed to be kept fully charged, typically what you’d need for a grid-tied system.
6. System Meter
This is used to monitor the status and performance of your grid-tied system, including the state of charge of the battery bank, PV panel productivity and electrical consumption. While this is an optional piece of equipment, it is highly recommended, otherwise you’ll be completely in the dark as to how well or not your system is performing and if something needs tweaking. A bit like driving your car without a gas gauge – not the best option.
As you can see, this type of system is quite a bit more complex than the relatively straightforward grid-tied solar power system (see Part 2 of this series). And that’s just half of the system. We’ll cover the rest in Part 3B, so please check back for the next installment.
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