How Solar Energy Works

Scientists have known for almost 200 years that sunlight can generate electrical energy when it falls on the right type of material. This phenomenon is known as the photoelectric effect.

A Simple Technology

The photoelectric effect is actually quite simple. It occurs whenever sunlight strikes a solar, or photovoltaic, cell, which is basically a sandwich of silicon (glass) and metal. Two types of silicon are used — one with a positive charge, and one with a negative charge.

When the two types of silicon are layered together, they form an electric field, with electrons from the negatively charged silicon seeking holes in the positively charged silicon. But the electrical field also acts as a barrier, preventing the electrons from actually filling the holes.

A solar panel consists of two layers of silicon — one with a positive charge and one with a negative charge.

Enter Sunlight

It takes the sun to break this logjam. When sunlight strikes a photovoltaic cell, it loosens the electrons and holes in the silicon atoms, allowing them to find each other.

When you add sunlight — and a little wire — you get an electric current.

If you connect the positive and negative layers by wire, electrons flow through the wire, creating an electrical current. This current is what we call electricity. We can use it to light our homes, run computers and tools, and do all the other things that make modern life so enjoyable and efficient.

Fun fact: When Albert Einstein won the Nobel Prize for Physics in 1921, it was not for his famous formula E=MC2. He actually won the Nobel for explaining the photoelectric effect — the fundamental principle behind solar panels.

Advances in Solar Technology

The technology behind solar cells continues to improve. In recent years, engineers, scientists, and inventors have made solar electric generation more efficient, more reliable, and much less expensive. In fact, the price of photovoltaic panels has plummeted by 90 percent in the last 30 years. Solar energy is now a significant energy source in countries around the world. And it keeps growing.