Photovoltaic power station facts for kids

A photovoltaic power station, also known as a solar park or solar farm, is a very large system that uses solar panels to make electricity. These big solar farms are connected to the main power grid, which is like a huge network that delivers electricity to homes and businesses. They are different from the smaller solar panels you might see on a house roof because they produce power for a whole city or region, not just one building.

Solar farms mostly use photovoltaic (PV) technology. This means they turn sunlight directly into electricity. There's another type of large-scale solar called concentrated solar power, which uses mirrors to focus sunlight and create heat to make electricity. But PV technology is much more common for big solar farms today.

When we talk about how much power a solar farm can make, we often use terms like megawatt-peak (MW_p) or gigawatt (GW). A megawatt is a million watts, and a gigawatt is a billion watts! Most solar parks are at least 1 megawatt in size, and some of the biggest ones can make over 1 gigawatt of power. By the end of 2019, there were about 9,000 large solar farms around the world.

Many of these big solar farms are owned by companies that specialize in making electricity. In the past, these projects often needed special help from governments, like payments for the electricity they produced (called feed-in tariffs) or tax credits. But now, making electricity with solar panels has become much cheaper. It's often as cheap as, or even cheaper than, electricity from other sources, so these special helps are usually not needed anymore.

How Solar Farms Started

Serpa Solar Park built in Portugal in 2006

The very first big solar park, which could make 1 megawatt of power, was built in California, USA, in 1982. Another even bigger one was built there in 1984.

Then, in 2004, Germany changed its rules to encourage more solar power. This led to many large solar parks being built there. Since then, hundreds of solar parks larger than 1 megawatt have been built in Germany, with over 50 of them being bigger than 10 megawatts.

Other countries like Spain, the USA, China, India, France, Canada, Australia, and Italy also started building many large solar farms. Today, the biggest solar farms being built can produce hundreds of megawatts, and some even over 1 gigawatt!

Where Solar Farms Are Built

Mosaic distribution of the photovoltaic (PV) power plants in the landscape of Southeast Germany

The amount of land a solar farm needs depends on things like how sunny the area is, how efficient the solar panels are, and how the panels are set up. For example, in sunny places, about 1 hectare (about 2.5 acres) of land might be needed for every megawatt of power. In less sunny places, it could be more than 2 hectares.

The best places to build solar farms are often on land that isn't used for much else, like old industrial sites or areas that aren't good for farming. Even on farmland, some parts of a solar farm can still be used for growing crops or helping nature.

Growing Crops and Solar Together

Agrivoltaics is a cool idea where the same land is used for both solar panels and farming. Recent studies show that this can actually make farms more valuable. The shade from the solar panels can help some crops grow better, and the farm gets income from both crops and electricity!

Sharing Space with Other Power Plants

Sometimes, several different solar farms are built next to each other, even if they have different owners. This can help them share things like the connection to the power grid or the cost of getting permits. Solar farms can also be built near wind farms. This is called "co-location" or "hybridization," and it helps use land or ocean space more efficiently. For example, a floating solar park was built on a dam reservoir in Portugal, combining solar and hydroelectric power.

How Solar Farm Technology Works

Most solar farms use solar panels placed on the ground. These panels can either be fixed in one position or they can move to follow the sun. Moving panels can make more electricity, but they also cost more to install and maintain.

Solar panels produce DC (direct current) electricity. But the electricity grid uses AC (alternating current). So, solar farms need special devices called solar inverters to change DC electricity into AC electricity. They also use transformers to increase the voltage so the electricity can travel long distances through the grid.

How Solar Panels Are Arranged

The solar panels are grouped together in "arrays." These arrays are the parts that turn sunlight into electricity. They are mounted on structures and connected to send power to the inverters.

Fixed Panels

Many solar farms use panels that are set at a fixed angle. This angle is chosen to get the most sunlight throughout the year. The panels usually face towards the Equator.

Panels That Track the Sun

To get the most sunlight, solar panels can be designed to follow the sun's movement.

• Two-axis trackers can follow the sun as it moves across the sky each day and as its position changes throughout the year. These systems need more space because the panels move, but they can produce about 30% more electricity in very sunny places.
• Single-axis trackers only follow the sun's daily movement from east to west. They don't adjust for the seasons. This method gets some of the benefits of tracking without needing as much land or costing as much as two-axis trackers.

Changing Power for the Grid

Solar panels make DC electricity, but the power grid uses AC electricity. So, solar farms have equipment to change DC to AC.

• Centralized inverters are large units that handle the power from a big section of solar panels.
• String inverters are smaller and handle the power from a single row or group of panels. Using many smaller inverters can be helpful if different parts of the solar farm get different amounts of sunlight.
• Transformers then boost the voltage of the AC electricity from the inverters to very high levels, so it can be sent through power lines to the electricity grid.

How Well Solar Farms Perform

How much electricity a solar farm makes depends on the weather, the equipment, and how it's set up. The main thing is how much sunlight hits the panels. Things like dust or dirt on the panels can also reduce how much light they get.

The efficiency of the solar panels themselves is very important. There are also small losses as the electricity travels from the panels to the grid. A "performance ratio" is used to measure how well a solar farm is working. A good solar farm should have a performance ratio of over 80%.

How Solar Panels Change Over Time

Older solar panels used to lose a lot of their power output each year. But modern panels are much better. A typical solar panel today might only lose about 0.5% of its power output each year. This means that after 25 years, a solar farm would still be producing about 88% of its original power. Many panel makers even guarantee that their panels will still produce a certain amount of power after 10 or 25 years.

The Business of Solar Farms

Solar power plants are built to sell electricity to the grid, just like power plants that use coal or gas. Most solar farms are owned by companies that produce electricity. These companies often hire other specialized companies to design and build the solar farm.

Before a solar farm can be built, it needs to get permission from the local government (called "planning approval"). It also needs approval to connect to the electricity grid. Solar farms need a lot of land, so where they are built is carefully planned. Sometimes, solar farms are built on old power plant sites to reuse existing connections to the grid.

Once a solar farm is built, it needs to be maintained. Solar plants don't need as much maintenance as other types of power plants because they don't have many moving parts. Companies often monitor the solar farm remotely to make sure it's working well and to schedule any necessary repairs.

The money a solar farm makes comes from selling electricity. The amount of money can depend on how much electricity is produced and the price of electricity at different times of the day.

How Solar Farms Are Funded

In recent years, solar technology has gotten much better and cheaper. This means that solar farms can now produce electricity at a cost that is similar to or even lower than traditional power sources. This point is called "grid parity."

Before grid parity was reached, solar farms often needed financial help from governments to compete. Here are some ways they were helped:

• Feed-in tariffs: These were special prices that electricity companies had to pay for renewable electricity, which helped solar farm owners make enough money to cover their costs.
• Renewable energy goals: Some countries made rules that electricity companies had to get a certain amount of their power from renewable sources. This encouraged them to buy solar power.
• Tax credits: These were tax breaks for companies that invested in solar power.

Now, because solar power is so much cheaper, many new solar farms are built without these special helps. Instead, companies compete in auctions to offer the lowest price for solar electricity. This has led to very low prices for solar power in many places around the world.

The main costs for solar farms are building them and the money borrowed to do so. But once they are built, the running costs are quite low because they don't need fuel.

Where Solar Farms Are Found

Solar farms are becoming more common around the world, especially in places with lots of sunshine and where electricity used to be expensive. The number of large solar farms has grown a lot, making up about 35% of all solar power capacity globally by the end of 2019.

China

China has become a leader in building large solar farms. Many of these are in the Gobi desert and connected to the power grid there.

Germany

Germany was one of the first countries to build many large solar farms, starting in the early 2000s. Many of these were built on old military sites or other unused land.

India

Bhadla Solar Park is the world's largest solar park located in India

India has also built many large solar farms. The Charanka Solar Park in Gujarat was once the largest group of solar power plants in the world. As of 2020, the Pavagada Solar Park and Bhadla Solar Park are among the largest in the world.

United States

In the United States, most large solar farms are in the southwestern states, where there is a lot of sunshine. States like California have rules that encourage the use of renewable energy.

Famous Solar Parks

Here are some solar parks that were the biggest in the world or their continent when they were built, or are famous for other reasons:

See also