What is Solar Power and How Does it Work? A Step-By-Step Guide - Part 2
Having discussed the basic definition of solar power in Part 1 of this series, we'll now move on to discuss the various types of systems used to produce solar power, beginning with grid-tied systems.
Grid-Tied - A Definition
A grid-tied solar power system (also referred to as grid-intertied, or on-grid or utility-interactive(UI)) produces solar electricity that is fed directly into the utility grid, hence the term grid-tied, as the system is tied, literally, to the grid. It's very often the case, e.g. during the day on weekdays when most families are away from their homes, that a grid-tied system is still producing electricity, even though very little, if any, is being used in the home. This excess energy is then fed into the grid, offsetting a residence's electrical usage, and causing the electricity meter to spin backwards, resulting in the account with the utility company being credited with that amount of energy (this is known as net metering or net billing, and is not available in all states, so please check with your utility company as to whether or not this option is available in your case). Thus, the utility grid is acting as a storage system and the electricity fed into the grid will be available for later use. In this way, a family's electricity bill can be drastically reduced, or even eliminated in some cases.
Components Of A Grid-Tied Solar Electric system
- Solar Panels
Also known as solar modules or photovoltaic (PV) panels, this is where all the magic of converting solar energy into solar power (or electricity) begins. We discussed the term "photovoltaic" and its definition in Part 1 of this series, but, briefly, this refers to the scientific process by which solar energy is converted into electricity. Basically, there are a number of silicon cells within each PV panel, each of which reacts with photons, or units of light, from the sun to produce direct current (DC) electricity.
One panel by itself will not produce a great deal of power as far as running household appliances, etc., is concerned, so, more often than not, multiple panels are combined to from an array to provide the required amount of power. In order to determine the number of panels needed, a rating is assigned to each panel in watts to indicate the panel's maximum power output under ideal sun and temperature conditions. Divide that into the required amount of power and that's approximately how many solar panels you'll need.
- Mounting Racks
Mounting racks are used to secure PV panels in place and to ensure they're properly orientated, i.e. facing south wherever possible to gain the maximum amount of solar energy. Depending on the amount of space available, obstructions, etc., 3 types of mounts are available: 1) poles that are set in concrete; 2) rooftop (the most common in urban areas); 3) ground (usually only an option where plenty of land is available). The amount and type of additional hardware needed will vary depending on which type of mount is selected.
- DC Disconnect
This is used to safely disconnect the flow of electricity from the PV panels in case of current overload.
The inverter takes the raw DC power produced by the solar panels and converts it to usable AC (alternating current) power, which can then be fed into the utility grid, and, subsequently, available to power household apliances, lighting, etc., since they all run off AC electricity.
- AC Breaker Panel/Inverter AC Disconnect
The breaker panel is where, as they say, "the twain shall meet", i.e. the electrical wiring of a dwelling connects to the power supply, be it either the grid or the solar energy system. It contains labeled circuit breakers used for both maintenance purposes and to protect the wiring from fires, etc.
The inverter AC disconnect, as its name implies, performs the same functions for the inverter and its wiring.
- Kilowatt Hour Meter
In the case where a building has a grid-tied solar electric system, most utility companies supply a bi-directional meter at no cost that can measure both the electricity being fed back into the grid as well as being pulled out of the grid.
As you can see, there's not a great deal in terms of complexity to a grid-tied solar power system, but the benefits and savings it can provide are far-reaching. This system doesn't provide complete energy-independence - in the case of a blackout, no power would be available. For that, stay tuned for Part 3 in this series, when we'll discuss the solution to that particular type of dilemma.
For more information on this subject and many others from the exciting world of solar and alternative energy, visit All-You-Need-Is-Solar.com, a resource for solar and alternative energy information and products.