What is Solar Energy?
Solar Energy is light from the sun which grows, warms, and sustains life here on earth. Solar Energy can be converted into Electricity through Photovoltaic Arrays. Photo means light and voltaics means it has to do with electricity. The Arrays are whatever captures the sunlight, most often these are solar panels. This is why solar panels are often referred to as PV (photovoltaic) arrays.
What makes a Solar Panel work?
A Solar Panel is made up of many individual Solar Cells. These Solar Cells are made up of a semiconducting material like silicon. Semiconducting is a fancy way of saying that these materials move (or conduct) the flow of electrons. Organizing the flow of electrons into a useful stream gives rise to an electric current. This current can then be used to charge batteries or power DC electronics but not typical AC wall outlets yet. To learn more about inverting DC to AC current see the next question.

Below is a diagram explaining the different layers inside each solar cell and how they conduct electrons into a useful current.
  1. Light comes in from the sun and hits the Solar Panel. The Solar Panel is made up of many Solar Cells which now absorb the sunlight. Inside the Solar Cell we find two different semiconducting layers: the p-type and the n-type. The p-type has an abundance of electrons and the n-type has few electrons.
  2. The incoming sunlight knocks off a few negatively-charged electrons from atoms in the electron-heavy p-type material.
  3. These energized electrons flow through the electron-barren n-type material.
  4. This constant one-way flow of electrons creates a Direct Current. The energized electrons flow through a circuit, are made to do electrical work charging batteries or powering light bulbs, and are sent back into the p-type to be energized again.
 Diagram of a Solar Cell

What is an inverter and why do I need one?
The light that comes from the sun that is converted into electricity gives rise to a DC current or Direct Current. This means that the flow of electrons (or electric charge) is one-directional. This one directional flow can charge batteries but cannot directly power the typical wall outlet in your home.

This is where a power inverter comes in. After the sunlight is converted into electric current by way of the solar panels, it then directly charges a bank of batteries to store up this useful electric energy. When you want to draw on this supply, the batteries send their DC current to the Power Inverter which inverts the current from DC to AC power which then can be used in common U.S. household (120 Volts AC) outlets.

Below are two of inverters we use:
  1. Model: Xantrex XW Inverter
    Up to 16kW of continuous DC to AC inversion
  2. Model: Xantrex 400 Series
    Up to 400 Watts of inversion
    Used with our Li-Ion Battery packs to
    provide two AC outlets anytime, anywhere
 Solar Panel Power Inverter: Xantrex
Solar Panel Power Inverter: Small Xantrex
What other parts are used in a Solar Powered system?
  1. Light comes in from the sun
  2. Many Solar Cells in a Photovoltaic Array produce a DC current
  3. The current is regulated by the charge controller to protect the battery bank
  4. The battery bank stores the electric charge to be used later. Devices using DC can draw power directly
  5. The electric current is inverted from DC to AC in the inverter and sent to power AC outlets
  6. Electronic devices can now draw power from the system like a normal wall outlet
 Diagram of a Solar Powered System
What should I look for on my monthly energy bill?
Below is a sample electric bill with the total cost and the total consumption circled in red.

This bill was chosen because the consumption is near the national average of 1250 kWh per month. Your local electric company will charge you for each kWh of power you use during a monthly period. Here the charge was roughly 16 cents per kWh ($206.71 / 1242) which is relatively high. The average cost per kWh is around 9.5 cents according to the Department of Energy Household Survey in 2001.

For more information about household energy consumption and a great pie chart of what uses the most energy is your household, visit EnergyStar.gov
Monthly Energy Bill