DIY Solar: How Small Solar Systems Work
Once you understand the basics of DIY solar and the options available to you, you’ll in a much better position to make sound decisions.
DIY Solar, in reality, is pretty basic. Solar electric systems, also known as photovoltaic, PV systems for short, convert sunlight into electricity. OK, you already knew that.
Solar cells—are the basic building blocks of a PV system—they are made out of semiconductor materials. When sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms.
This phenomenon is called the "photoelectric effect." These free electrons then travel into a circuit built into the solar cell to form electrical current. Only sunlight of certain wavelengths will work efficiently to create electricity. DIY solar systems can still produce electricity on cloudy days, but not as much as on a sunny day.
The basic PV or solar cell typically produces only a small amount of power. To produce more power, more solar cells can be interconnected to form modules. PV modules range in output from 10 to 300 watts.
If more power is needed, several modules can be installed together on a building or at ground-level in a rack to form a PV array.
PV arrays can be mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun, allowing them to capture the most sunlight over the course of a day.
Because of their modularity, DIY solar systems can be designed to meet any electrical requirement, no matter how large or how small. You also can connect them to an electric distribution system (grid-connected), or they can stand alone (off-grid).
A typical small DIY solar electric, or photovoltaic (PV), system consists of these components:
Modules or panels (which consist of solar cells)
Arrays (which consist of modules)
A typical small DIY solar electric system usually includes the following balance-of-system components:
Mounting racks and hardware for the panels
Wiring for electrical connections
Power conditioning equipment, such as an inverter
Batteries for electricity storage (optional).
Stand-by gasoline electric generator. (Optional)
A PV system can be a stand-alone, or “off-grid” system, or connected or “tied” to the utility grid. If tied to the utility grid, it will have these components:
• One or more PV modules, which are connected to an inverter
• The inverter, which converts the system's direct-current (DC) electricity
to alternating current (AC)
• Batteries (optional) to provide energy storage or backup power in case of a power interruption or outage on the grid. AC electricity is compatible with the utility grid. It powers our lights, appliances, computers, and televisions.
What Is Net Metering?
Net metering is a billing mechanism that credits solar energy system owners for the electricity they add to the grid. For example, if a residential customer has a PV system on the home's rooftop, it may generate more electricity than the home uses during daylight hours.
If the home is net-metered, the electricity meter will run backwards to provide a credit against what electricity is consumed at night or other periods where the home's electricity use exceeds the system's output. Customers are only billed for their "net" energy use. On average, only 20-40% of a DIY solar energy system’s output ever goes into the grid.