How Is Energy Created From Solar Panels?

Solar panels have become increasingly popular sources of renewable energy over the past decade. As concerns grow over fossil fuels’ environmental impact and finite supply, solar power offers a clean and virtually limitless alternative. Solar panel installations are accelerating across residential and commercial buildings worldwide. Understanding how solar panels work helps illuminate the immense potential of solar energy to meet our future energy needs.

Table of Contents

How Solar Panels Work

Solar panels work through the photovoltaic effect, which is a process that converts sunlight into electricity. When sunlight hits the solar panel, it excites the electrons in the semiconducting material, causing them to move and generate electric current.

Solar panels are made up of many individual solar cells, which are usually made from silicon. Silicon is a semiconductor, meaning it shares properties of both conductors and insulators. When sunlight enters the cell, photons from the light knock electrons loose in the silicon atoms, allowing them to flow freely.

The solar cells have positively charged silicon on one side and negatively charged silicon on the other, forming an electric field. Conducting wires connect the positive and negative sides, forming a circuit. The electrons want to go to the positive side, but they can only travel that path if the circuit is closed allowing current to flow.

This movement of electrons from the negative to positive side generates the electricity that solar panels produce. The photovoltaic effect constantly generates electricity from sunlight hitting the solar cells during the daytime.

Solar Irradiance

Solar irradiance refers to the strength of the sun’s energy that reaches the Earth. The sun produces an enormous amount of energy, known as solar irradiance, in the form of electromagnetic radiation. Only a tiny fraction of this energy reaches the Earth, but it provides a significant source of renewable power.

The amount of solar irradiance that arrives at the top of the Earth’s atmosphere is about 1,360 watts per square meter. This is known as the solar constant. However, the amount of solar irradiance that actually reaches the Earth’s surface is reduced due to absorption and scattering by the atmosphere. On average, about 1,000 watts per square meter reaches the Earth’s surface on a clear day.

Solar irradiance levels vary throughout the day and year. The maximum solar irradiance occurs when the sun is directly overhead, providing about 1,100 watts per square meter on a clear day. Solar irradiance is higher in summer and lower in winter, due to the tilt of the Earth’s axis. It also varies due to cloud cover, pollution, and latitude. Areas closer to the equator receive more solar irradiance than areas farther away.

Understanding solar irradiance is important for solar power. Solar panels work by converting the sun’s irradiance into electricity. The higher the irradiance, the more electricity a solar panel can produce. Tracking daily and seasonal variations in irradiance allows solar installers to optimize panel positioning and predict the energy output over time.

Solar Panel Components

Solar panels are made up of solar cells, electrical connections, a glass covering, and a frame. Here are the key components:

Solar Cells – These are made of semiconducting materials, usually silicon, that directly convert sunlight into electricity through the photovoltaic effect. Solar cells are typically very thin and several inches across. Many individual solar cells are connected together and encapsulated between a transparent top covering and a backing material to form a complete solar panel.

Glass Covering – The solar cells are protected from weather and impact by a top covering made of tempered glass, high transmittance plastic, or another transparent protective material. This allows light to pass through to the solar cells while protecting the components.

Frame – This provides structural support and rigidity to the panel. Frames are commonly made of aluminum which is lightweight, corrosion resistant, and durable. The corners are also reinforced to protect the solar cells during transport and installation.

Junction Box – The electrical connections for the solar cells are routed through a junction box on the back of the panel. This contains terminals to connect the electrical wiring that combines the output of all the individual cells into a single circuit.

DC to AC Conversion

Solar panels produce direct current (DC) electricity, but our homes and the electric grid run on alternating current (AC) electricity. In order to use the electricity from solar panels, the DC current must be converted to AC current. This is done using a component called an inverter.

Inverters play a critical role in solar energy systems. They act as an interface between the solar panels and the utility grid. Here’s how inverters work to convert DC to AC:

The DC current from the solar panels flows into the inverter.

Inside the inverter, the DC current passes through power electronics that switch the direction of the current flow back and forth very rapidly.
This rapid switching creates a sine wave pattern in the current, effectively converting it into AC electricity.
The inverter also increases the voltage of the electricity to the standard AC voltage level for connection to the grid.

Most inverters also include important safety features and optimization algorithms to maximize system performance.

By converting the solar panel DC output into usable AC power, inverters are a crucial component that enables our homes and businesses to run on clean solar energy.

Connecting to the Grid

Most home solar panel systems connect directly to the local electrical grid to allow excess electricity to be fed into the grid during the day. This enables households with solar power to earn credits from their utility provider for the electricity they generate but don’t use. The credits can be used to offset electricity drawn from the grid later, like at night when solar panels aren’t generating power.

To connect to the grid, solar panel systems require:

A bi-directional utility meter that spins forwards when consuming grid electricity and backwards when feeding into the grid
An inverter to convert the DC electricity from the solar panels into AC electricity for the grid

A grid connection agreement with the local utility company

The main alternative is an off-grid solar system not connected to utility electrical infrastructure. Off-grid systems require batteries to store excess solar energy for use at night. They are more complex and costly to install and maintain. Off-grid systems make the most sense for remote locations without access to an electrical grid.

Grid-tied systems are generally the most practical and cost-effective option for residential homes. Excess solar electricity is handled automatically by the grid rather than requiring expensive battery storage. The grid also acts as a backup power source when solar panels aren’t generating enough energy.

Solar Panel Orientation

The orientation of solar panels can have a significant effect on energy production. Solar panels work by absorbing sunlight, so optimizing their exposure to the sun’s rays is crucial.

The main factors that impact a solar panel’s orientation are direction and tilt. Direction refers to the compass direction the panels face. In the northern hemisphere, south-facing panels tend to produce the most energy, as they receive direct sunlight throughout the day. East and west-facing panels may also work, but their energy production peaks in the morning and evening respectively when sunlight strikes their surface at an angle.

Tilt refers to the vertical angle of the panels. The optimal tilt angle equals the latitude of the installation location. Tilting the panels allows them to be perpendicular to the sun’s rays at solar noon (when the sun is highest in the sky). This maximizes energy absorption. However, fixed tilt angles are usually set to optimize annual energy production, not just noontime output. There are also adjustable tilt mountings that can follow the sun’s path across the sky.

Overall, orienting solar panels to directly face the equator (south in the northern hemisphere, north in the southern hemisphere) and tilting them based on latitude is the best way to maximize solar energy production.

Solar Panel Maintenance

Proper maintenance is crucial to ensure solar panels operate efficiently for their full lifespan of 20-30 years. Here are some key maintenance tasks solar panel owners should regularly perform:

Cleaning Panels

Dirt, dust, pollen, and bird droppings can accumulate on solar panels over time, blocking sunlight and reducing power output. Panels should be cleaned every few months using water, mild dish soap, and a soft sponge or cloth. Avoid abrasive materials that could scratch the glass. For large solar panel arrays, specialized solar panel cleaning robots can automate the cleaning process.

Checking Connections

It’s important to check that all wiring connections to your solar panels, inverters, combiner boxes, and junction boxes are intact and secure. Loose connections can reduce power output or create safety hazards. Tighten any loose wiring connections and have an electrician address any severely degraded cables or connectors.

Monitoring Performance

Solar panel monitoring systems track power output metrics like energy yield, performance ratio, and degradation rates. Review monitoring data regularly to identify any underperforming panels and troubleshoot issues before they worsen. Monitoring ensures your solar array operates as efficiently as possible.

With routine cleaning, connection checks, and performance monitoring, solar panel owners can maintain optimal system performance for many years. Proper maintenance keeps your solar investment running smoothly.

Solar Energy Storage

One of the main benefits of solar energy is the ability to store excess electricity generated during sunny days for use at night or on cloudy days. This is typically done using rechargeable batteries paired with the solar panel system.

Lead-acid batteries are the most commonly used, as they are reliable and cost-effective. However, lithium-ion batteries are gaining popularity as prices decline, offering a longer lifespan and reduced maintenance. Battery banks are sized according to the solar system’s power output and the home’s energy needs.

When the solar panels produce more electricity than a home is immediately using, the excess charges the batteries. At night or when solar production is low, the home can then draw from battery reserves. This gives homeowners power independence and resiliency.

Solar battery storage supports renewable energy growth by addressing intermittency challenges. With enough storage capacity, solar power can effectively become a 24/7 energy source for homes and businesses.

The Future of Solar

The future is looking bright for solar power. As technology continues to advance, solar panels are becoming more efficient and cost-effective. Some key developments we can expect to see include:

Improved solar cell efficiency – Companies are finding new ways to get more electricity out of each solar cell. This includes using new materials like perovskites that are easier and cheaper to manufacture but can still convert over 20% of sunlight into usable energy.

Thinner, flexible solar panels – New manufacturing processes are allowing solar panels to be made thinner and more flexible. This will open up many new applications for solar technology to be integrated into roof shingles, windows, vehicles, clothing, and more.

Better energy storage – Storing solar energy collected during the day for use at night is a major challenge. But battery storage technology is rapidly improving, with costs dropping dramatically in recent years. Soon affordable home battery systems coupled with solar panels will allow clean solar energy 24/7.

Expanded infrastructure – With solar electricity costs becoming cheaper than fossil fuels, we can expect large-scale solar deployments across rooftops, solar farms, and local power grids. Investments in infrastructure and policy will help solar power play an ever-increasing role in our energy mix.

With these new developments, solar power will continue its rise to become one of our predominant global energy sources and play a major part in the transition to a sustainable clean energy future.