What is a Solar Panel? (Solar Panels Explained)

Solar panels convert sunlight into electricity. 

In actual fact, solar panels can convert many light sources into electricity, but the most powerful source will always be sunlight.

A solar panel is made up of multiple smaller solar cells. These solar cells are pieces of semi-conductor, usually silicon. A large home solar panel will be built from 60 to 80 solar cells which are then placed in a frame and covered with glass. In addition, you can also get thin flexible solar cells wrapped in a plastic coating of PET or ETFE.

When photons of sunlight hit these cells it energizes electrons to create an electric current. This is known as the ‘Photovoltaic (PV) Effect’ and solar panels are also referred to as ‘PV Panels’ for this reason.

When this electric current from multiple solar cells is combined it is enough to power appliances and electrical loads.

With this simple explanation of solar panels we can now take an in-depth look at their uses, history, benefits, and the inner workings.


What Are Solar Panels Used For?

The use of solar panels has grown rapidly since the turn of the century. Next time you go out keep your eyes peeled and you’ll see them everywhere from rooftops to road signs.

Solar panels are very useful for producing electricity anywhere there is sunlight (which is most areas of the world!)

Here are the most common ways solar panels are used:

Homes and Buildings

solar panels on a building

The use of solar panels on houses is growing at an outstanding rate. In fact, the average annual growth of solar power is nearly 40% since the start of the century, explains Nick Jelly in Renewable Energy (2020). Plus 40% of this growth is accounted for by distributed systems rather than solar farms.

Solar panels are used on houses and buildings to supplement usage of electricity from the main grid. It allows an individual property to generate its own electricity and top up its supply from the main grid. If you look at the rooftops of houses, you will now regularly see them covered in solar panels.

While it is possible to run a house completely from solar panels, it is not that practical. Often there is not enough space to generate enough electricity. Adding to this, solar panels don’t work at night so electricity must be supplied by the main grid at these times.


Solar Farms

Solar farm in the countryside

Farms are no longer restricted to crops and animals. You can now get solar farms! 

In agricultural areas with large fields, the popularity of solar farms is growing.

A solar farm is simply a huge field covered in solar panels. It is an efficient way to create a large amount of electricity for the general population or commercial needs. 

Solar farms can vary in size, on average from 0.5 MW to 15 MW (Mega Watts). 1MW can power over 500 homes for a year so a 15MW solar farm could power more than 7500 homes each year. 


Remote Locations

Solar panels allow you to generate electricity in remote locations rather than needing to extend power from the main grid. Often it is much more cost effective to use solar power in this situation. 

Example, could be a cabin, garden shed, portable CCTV equipment, or street lighting like this:

Solar panels on a remote street light

Instead of needing to keep replacing batteries or run a diesel generator, solar panels provide a maintenance free, cost efficient and clean way to produce off-grid electricity.


Off-Grid Vehicles

Solar panels on a narrowboat

Owners of vehicles like RVs, campervans, boats, vans, and food trucks absolutely love solar panels.

If you live or work in a vehicle it is not always easy to find an electrical hook up. Imagine you are on a boat at sea… There’s nowhere to plug in.

With solar panels, you can generate electricity to run your appliances and charge devices. Plus you can charge deep cycle batteries to store electricity for later.

In the past, you would need to go back to shore to charge batteries or use a dirty noisy generator. Solar panels solve this problem using the sun’s energy.


Battery Charging

The beauty of solar panels is that they produce DC electricity which is what you need to charge any type of battery. You can hook a solar panel up to a battery and leave it to charge. The speed depends on the panel power, sun conditions, and size of battery.

Common examples of using solar panels to charge batteries include:

  • Deep cycle batteries
  • Vehicle starter batteries
  • Phone charging
  • Portable power banks
  • Solar generators
  • Remote camera equipment

Aerospace

Solar panels in space above clouds

The original use for solar panels was in space! In fact, the international space station has a huge solar array which delivers ample electricity for its operations.

The benefit of solar power in space is that the sun’s energy is more intense as it doesn’t have to pass through the Earth’s atmosphere or compete against weather conditions like cloud cover.


The History of Solar Panels

The first time a photovoltaic effect was seen in a solid cell was in 1877 which was created with Selenium. This was the first step in more than a century of developments to get to what we know as a solar panel today. It was Charles Fitz who went on to create a thin-film Selenium photocell in 1883 in an attempt to harness sunlight for electricity. 

The problem at this time was that it was incredibly expensive and terribly efficient. Just 1% of the sun’s energy was converted to electricity, which had no practical applications.

From this point, there became a long wait until 1940 for any advancements in efficiency. Next Russel Ohl stumbled upon the photovoltaic effect in silicon in the Bell Laboratories, USA. This yielded significant progress from making a silicon rod via slow crystallization. 

As we know today, silicon is a key ingredient in electronics as a semiconductor. It was the advancements in using this element for transistors that helped the solar industry. By 1954 a solar cell with 6% conversion efficiency was developed giving a 10 times better result than previous devices. This was the first time the world saw solar cells with a useful output.

Outside of high tech industries like space programs, solar cells still had little use in everyday life for years to come. Over time research enabled costs to be lowered to a point in the 1980s when the technology was touted for wider use. 

By the turn of the century, things really started to ramp up and demand began to spike. Since then the average annual growth of solar panels is around 40%. This in turn has led to increased efficiency of over 20% coupled with huge cost reductions in manufacturing. In fact, the cost of manufacturing between 2011 and 2018 fell by a factor of 3.5.

After the invention of silicon solar cells, it took 60 years for the efficiency to reach over 20% and the cost to fall several hundred times. Now, the price and electricity production makes solar power a competitive, and often cheaper, source of energy compared to fossil fuels.


How Do Solar Panels Work?

Solar panels work by absorbing energy from the sun and converting it into electricity. 

Each solar cell is made up of layers. These are layers of silicon which are either positively or negatively charged using phosphorus and boron respectively. This opposite charging of two layers creates an electric field, just like a magnetic field with a positive and negative end.

When a photon of sunlight hits the solar cell it knocks an electron free from its atom into the electric field. The electrons can then flow in a directional current (DC) to produce electricity. 

This current then flows from the solar cells into a wire to wherever the electricity is needed. In a house, the solar panels are connected directly to a solar inverter which converts the DC to AC electricity in order to run appliances. Or be sent to the main grid.

In an off-grid solar system, the electricity will be used to charge a deep cycle battery. You can then draw energy from the battery using a power inverter. 

For more detailed information read our guide to How Does a Solar Panel Work?


Benefits of Solar Panels

We’ve touched on a few of the benefits of using a solar panel. They are an exceptional source of electricity with a range of amazing advantages. Let’s take a direct look at the reasons why solar panels have grown in popularity so quickly.

Free Electricity

They say nothing in life is free, well they didn’t know about solar power. It’s true that the initial purchase needs investment, but after this, there is no cost to generate electricity. 

Once you recoup the cost of buying the equipment, the electricity production won’t cost you a penny. Adding to this, with a home solar array you can earn credit by sending excess electricity to the mains grid. This means you can use Net Energy Metering to actually get paid! You won’t earn money directly but it will be offset against your energy bill. 

If you have a completely off-grid system, like on an RV, you can have electricity without any cost or need to deal with energy suppliers.

Use Off-Grid

Solar panels can be used anywhere there is sunlight, so most places on Earth. You could install solar panels on a remote cabin in the mountains, on a desert island, on a boat, or carry one on your backpack while hiking.

Solar panel on a hut roof

You don’t need any hook up to the main grid! This is a huge benefit as structures like remote cabins don’t need the expense of installing power lines. You don’t even need fuel to run a generator. All you need is sunlight.

Environmentally Friendly

As we shift away from the reliance on fossil fuels and into a growing electrical age, solar panels make complete sense. To produce electricity there are no polluting gases or carbon emissions. The only carbon footprint comes from manufacturing, transporting, and installing. After this, it is completely eco-friendly. Plus they have a long lifecycle with a durable design that lasts at least 25 years (and usually a lot longer).

Quiet and Clean

Along with zero carbon emissions, solar panels are a clean and quiet source of off-grid electricity. In the past, humans would rely on diesel generators and combustion engines to deliver power away from the main grid. This presents a number of problems including noise and toxic gas. Both of these issues are eradicated with solar power which generates electricity in complete silence with no noticeable byproducts.


Disadvantages of Solar Panels

You might be thinking that there’s nothing these magical panels can’t do… Well, while they are pretty amazing, solar panels do have their drawbacks. Like any renewable energy solution, you need to account for certain limitations. The weather, climate, and time of day can all cause issues with solar panels.

Weather

Weather conditions affect power output of solar panels dramatically. For optimal use, they need direct sunlight. While solar cells will still generate electricity in shade or under cloud cover, it can reduce performance by over 70%. That’s a serious drop in electricity output when it’s cloudy.

Time of Day

You will only generate a decent amount of electricity for a small portion of the day. For best results, you need peak sun hours which lasts for 4 -5 hours a day in most parts of the world. During early mornings and evenings, the energy harnessed from the sun reduces enormously.

Plus solar panels do not work at all at night. There will be no electricity production during darkness. And no, moonlight doesn’t help! To account for this, many systems use batteries to store electricity generated during the day to use at night.

Time of Year

Solar panels will be more effective during the summer than in the winter. This is because during the winter you are further away from the sun reducing the amount of energy reaching your solar cells. That’s why it’s warmer in summer than it is in winter!

Climate

As you know, the climate and weather varies around the globe. For example, it is hotter at the equator compared to Northern Canada. Again, this is due to the position of the Earth in relation to the sun. In simple terms, the sunnier and warmer your climate the better suited it is to solar panels.


How Much Electricity Do Solar Panels Produce?

On average, solar panels produce around 8 – 10 watts of power per square foot. 

And a normal home solar panel will generate 150 – 250 watts of electricity per hour. 

The amount of electricity a solar panel will produce depends on its size. For example, you can get 5 Watt solar panels to trickle charge car batteries and 300 Watt panels for commercial installation.

If you’re installing solar panels you will need to work out your total energy consumption to find out how many solar panels you require. In a home, you can find this information on your energy bill or smart meter.


Where Can You Buy Solar Panels?

You should be able to find a solar panel installer in your local area. This is a good place to start in order to get quotes for a complete home installation. There are a huge number of manufacturers to choose from including high profile electronics companies like Tesla, Panasonic, Toshiba, Hitachi, LG, and Sharp.

For off-grid solar panels, you can buy them and install yourself. There’s a wide range of choices online at Amazon, Walmart, Renogy, Eco-Worthy, and more.


FAQ about Solar Panels

Time to answer the most common questions about solar panels.

Do solar panels work at night?

No, solar panels do not work at night. They need sunlight in order to generate electricity. Moonlight will not work with solar panels. The best option is to store electricity in a battery to use at night.

How long do solar panels last?

Solar panels are incredibly durable and should last at least 25 years. Most manufacturers offer a 25 year power output warranty but panels can last much longer than this, even 40+ years.

What are the 3 types of solar panels?

The 3 major types of solar panels are monocrystalline, polycrystalline, and thin-film. Each uses a different cell structure which delivers varying performance. Monocrystalline is the most efficient, followed by polycrystalline. Thin-film solar panels are rare, they are cheap to create but lack performance.

Do solar panels need sun or just light?

Solar panels can work without direct sun. Just light will be enough to create electricity, for example on a cloudy day, but they perform much better with direct sunlight. You should always mount a solar panel where it will receive direct sunlight.

What is the most efficient solar panel?

The most efficient type of solar panel is monocrystalline. They use solar cells made up from a single silicon crystal and have a conversion efficiency of over 21%. Monocrystalline solar panels are deep black in color and have square cells with the corners cut off.

Can solar panels power a whole house?

Yes, solar panels can be used to power a whole house. You simply need enough solar panels to meet your energy requirements. There are limitations however as often there is not enough space to mount solar panels in a sunny area. Plus, you won’t generate electricity at night so you need to fall back on the main grid or store energy in batteries.


Solar Panel Summary

By now you should be able to see why solar panels are so popular. They allow you to generate free and clean electricity.

You can use them at home to reduce utility bills or in off-grid situations to add electricity to remote locations. 

While the sun is shining, you’ll love the way solar panels work to produce energy for your appliances. Plus in the future we can certainly look forward to increasing efficiency and lower prices to make it accessible to more and more people.