How Do Solar Panels Work?

By Subodh / November 15, 2013

More people are becoming interested in solar power. This might be because they’re beginning to worry about the effects of humankind on global warming. Maybe they’d like to go off the grid by generating their own electricity. Or perhaps they’re simply curious about the science behind how solar power works. Whatever the reason, there seem to be more solar-powered products and solar power generation kits available on the market today.

Solar Cells

If you look closer at a solar panel, you’ll see that it contains many relatively smaller wafers throughout its surface. These are the solar or photovoltaic cells. This is where sunlight which is absorbed is converted into usable electricity. Let’s break down a solar cell even further. If you take a closer look at one cell, you’ll find that it has a number of parts.

solar-panels

Solar Cell – 2 Slices of Silicon

Each solar cell contains two slices or pieces of silicon. While both pieces are made of silicon, they are not identical. Instead, one piece has been infused with small amounts of phosphorus while the other piece is infused with small amounts of boron. These trace elements are important because they help facilitate the solar energy conversion process. You see, the silicon piece with phosphorus additives contains a greater number of negatively charged particles compared to plain old silicon. In contrast, the piece infused with boron contains fewer negatively charged particles. This difference is what helps get things started.

When the two silicon pieces are brought into close contact with one another, the negative charges will tend to transfer very quickly from the phosphorus-infused piece to the boron-infused one. This transfer ends up creating a positive charge in one layer and a negative charge in the other.

Sunlight Absorption

When the rays of the sun are absorbed by a solar cell, this causes negative particles in the 2 silicon pieces to become loose. It’s these negative particles which will flow in order to become the current that will be usable as electricity. However, for that to happen, the negative particles or electrons need to be given a path to follow.

Solar Cell – Metal Strips

Each solar cell contains strips of metal which act as conductors. So when the sun’s rays end up knocking those electrons loose from the 2 silicon wafers, these electrons end up following the route set out by the metal strips. This route will then lead to the wires which collect the current and either collect it in a battery or route it directly into the building where it will be used. However, the current that is created in this way is known as direct current or DC power. It’s not the kind of electricity that’s used to run appliances and large devices in a house or office. So there will be a need to use some form of inverter to convert the DC power into alternating current or AC power.

Solar Cell – Coating

One of the things that needed to be worked out about solar cells is that the silicon layers could potentially act as reflectors or mirrors. So instead of the sun’s rays being absorbed by the cell, they might just be reflected away. This is why the top of the cell features a layer of coating which is meant to prevent this form of reflection and instead absorb as much of the light as possible. This way, there will be more of the sun’s photons available to unmoor electrons from the 2 silicon layers.

Solar Cell – Cover

There’s also a need to make sure that all solar cells, and all solar panels in general, receive some form of protection from the elements. You don’t want rain, snow, sleet or other weather conditions to ruin the components of the solar panels and cells. That is why each cell and panel comes with a cover made of glass. It’s transparent so that it doesn’t impede the absorption of sunlight, but it’s also waterproof and it offers a barrier to the elements, so that the various components of the solar energy collection system remain protected.

Angles

In order for solar panels to be maximized, they need to be exposed to as much sun as possible. That is why in certain cases, panels are mounted onto platforms which track the movement of the sun. As the sun moves through the sky, the position and angle of the solar panel are changed, so that it’s absorbing the most possible light from the sun.

In cases where motorized tracking isn’t available, a home owner will have to figure out how the orientation of her roof and the location of her home, throughout the seasons, will affect the amount of available sunlight. Based on this information, she will be able to calculate how many solar panels she will need in order to meet her energy needs. Care must also be taken so that none of the panels end up in the shade of any large trees or other obstacles.