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Solar energy

How Does Solar Power Work?

Solar farm in the United States

The Sun is the main source of power on planet Earth even we talk about solar energy, wind power or fossil fuels.

The Sun produces the sunlight, the wind, and is also the source of energy that was stored by ancient plants and animals, which died and were turned in the today’s reserves of fossil fuels.

At any moment, our star sends us about 174.000 TW (terrawatts) of clean energy, and that is about ten thousand times much more energy than our civilization uses.

To understand how does solar energy work, we first need to talk about solar panels.

How do solar panels produce energy?

Solar panels contain smaller units called solar cells, and the most common solar cells are made of silicon. Silicon is a semiconductor that is the second most abundant element on the planet.

In a solar cell, silicon is put between two conductive layers. Each silicon atom is connected to its neighbors through a number of four strong bonds. These bonds have the role to keep the electrons in place, so there is no current flow.

A silicon cell uses two different layers of silicon. The N-type silicon layer has an increased number of electrons, while the P-type silicon layer that has an increased number of spaces for electrons, which are called holes.

Where the two layers of silicon meet, electrons can wander across the P/N junction, which will leave a positive charge on one side and will create a negative charge on the other side.

How do solar cells produce electricity?

The sunlight is a flow of tiny particles called photons. When one of these photons strikes the silicon cell with enough energy, it can knock an electron from its bond, leaving a hole.

The negatively charged electron and the location of the positively charged hole are now free to move around, but due to the electric field at the P/N junction, they will go only one way.

The electron will be drawn to the N side, while the hole is drawn to the P side.

The moving electrons are collected by thin metal fingers located at the top of the cell.

From there, they flow through an external circuit to do electrical work like powering a light bulb, gadget or appliance, before returning through the conductive sheet of aluminum located on the back of the PV panel.

Each silicon cell produces up to 5W, so to produce a solar PV panel with an output of 300W, we have to use a number of 60 solar cells.

To power a smartphone or a laptop, a 60W solar panel would be enough, but to power an entire house we have to use a much larger number of solar panels.

How to use solar energy in your advantage?

To benefit from this free source of energy represented by our Sun, the only thing to do is to install a solar PV system or solar heaters on your roof, because in both cases you will start paying smaller energy bills.

Solar PV system

To understand if your location is suited for solar, you have to contact a solar installer that will tell you if solar is a good option for you.

When installing the solar PV system on your roof, the installer will take care of the panels, the solar panel cable sizing, charge controllers, inverters, utility meter, and the connection to the electric grid.

Once you have the PV system installed on your roof, you will start generating your own power during the day.

The maximum output of the PV system will be reached during the summer, when the sky is clean and the days are longer.

If you generate more power than you consume, the excess energy will be sent back into the grid to power your neighbors.

The utility company will pay you for all the energy sent back into the grid by your solar power system.

However, to benefit even more from your solar PV system, you can use a battery system to store the excess energy. That energy will be used during the night and in the next morning or in the days will less sun. This way you can save even more money on energy bills.

Solar heater

A solar heater can reduce your energy bills because you will no longer use electricity to heat the water.

Solar heaters usually work well from April to October. However, the are solar heaters that work even in the winter, but due to this feature, they cost three to four times more money than regular solar heaters.

Can a house run on solar power alone?

A solar PV system that is properly sized, can power an entire house all day long.

To find out the size of the PV system that can cover all your household energy needs, you have to start by measuring your daily consumption.

You can do this by checking the meter every day at the same hour. Do this for a couple of days, and you will have the average consumption of energy per day.

Once you know this value, you have to order a solar PV system that can the energy demand of your house.

A battery system can help you store some energy that can be used during the night or on cloudy days.

For the winter, you can’t rely on solar for heating. Solar doesn’t work well in the winter because the days are much shorter and mostly cloudy.

How does solar power work at night?

During the night, solar panels don’t work because there is no sunlight. However, solar panels start working in the morning even if the sky is cloudy.

In cloudy days, the panels will produced a reduced amount of power. The maximum output of your PV system is reached in the summer during a day with clear sky.

As we get closer to winter, the PV system will produce less and less power because the days will become shorter and the Sun is harder to see in the sky.

As we get closer to the spring, the days become longer and the panels start producing more power.

Do solar panels work in rain?

Solar panels do work in the rain even if the amount of energy produced is reduced. The presence of light even if talk about diffused light, is enough for the panels to produce electricity through the photovoltaic effect.

The rain is also useful because it washes off the dust and debris from the panels, and keeps them clean.

Dirty solar panels produce less energy even in the summer, because the surface on the panels used to capture the sunlight is almost opaque.

This is the reason why you should keep your panels clean all the time.

Do solar panels work when the power goes out?

On-grid solar power systems stop working in case of an outage, to protect the workers sent by the utility company to solve the issue in the grid.

Once the power in the grid is back, the on-grid solar power system will start working again to produce clean electricity for your house.

Off-grid solar power systems use a battery system to store the excess energy produced during the sunny days. In case of an outage, the off-grid solar power system will continue to work because is not connected to the grid.

Final thought

The Sun is the most important source of clean power available for us here on the planet. Once you install a solar power system on your roof, you will start saving money on energy bills, and the carbon footprint of your household will be reduced.

Article written by:

I am a writer and reporter for the clean energy sector, I cover climate change issues, new clean technologies, sustainability and green cars. Danny Ovy

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