How Is Solar Energy Converted Into Electricity Step By Step?

Solar power has emerged as one of the most important renewable energy sources in recent years. As concerns about climate change and reducing greenhouse gas emissions continue to grow, nations around the world are looking to expand their use of clean energy like solar power. According to one source, solar power was the number one new source of energy generation added worldwide in 2016 (Source). With costs continuing to fall and efficiency improving, solar energy is becoming more accessible and affordable for homes and businesses. This article will provide an overview of how solar panels actually work to convert sunlight into usable electricity.

How Solar Panels Work

Solar panels work through the photovoltaic effect, which describes how certain materials are able to convert sunlight directly into electricity. When light shines on a solar panel, photons from the sunlight are absorbed by the solar cells in the panel, which are made of semiconducting materials like silicon. The energy from the photon knocking loose electrons from the solar cell’s atoms creates an electric current. The newly freed electrons flow through the panel’s internal circuitry collect the electrons and route them to terminals to create a DC electric current (How do solar panels work?, 2022).

Solar Panel Components

Solar panels are made up of solar cells, wiring, and protective glass.

Solar cells are made of silicon and are responsible for converting sunlight into electricity through the photovoltaic effect. When sunlight hits the solar cells, electrons are knocked loose from the atoms in the silicon. The free electrons flow through the solar cell, creating an electric current.

The solar cells are connected together with thin wires to allow the electric current to flow from cell to cell and eventually out of the panel. The wires on the front of the panel are thinner and spaced further apart to allow sunlight to hit the solar cells. On the back of the panel, thicker wires combine together into cables that transmit the electricity out of the panel.

A glass cover protects the delicate silicon cells and wiring from impact and weather damage. The glass is specially treated to be anti-reflective to maximize the amount of sunlight reaching the solar cells. An aluminum frame provides additional protection and mounting points to install the solar panel.

Together, these components work to efficiently convert sunlight into electricity and transmit that power for use in buildings, on the grid, or to charge batteries.

Source: https://www.energysage.com/solar/what-are-solar-panels-made-of-list-of-solar-pv-materials/

Generating Direct Current

The process of generating electricity from solar panels starts when sunlight hits the solar cells of the panel. Solar cells are made of semiconducting materials, usually silicon, that are specially treated to form an electric field across the cell. When sunlight photons hit the solar cell, their energy dislodges electrons from the atoms of the semiconductor material, causing electron flow and generating a DC current (Coremax 2021).

The solar cells are wired together in a series circuit layout so that the currents from each cell add together to produce a total current output. The amount of current generated depends on the intensity of sunlight hitting the solar panel. More intense sunlight results in more photons hitting the solar cells, which creates a larger flow of electrons and higher DC current output (Coremax 2021).

This DC current generated by the solar cells flows through the interconnected wiring in the solar panel and is output through the cables coming from the solar panel. This electricity can then be used to directly power DC appliances and devices or, for AC devices, must first be converted to AC current using an inverter.

Coremax. 2021. “7 Things You Need to Know Before You Build Your OFF GRID Solar System.” Coremax Technologies. October 18, 2021. https://www.coremax-tech.com/7-things-you-before-build-your-off-grid-solar-system/.

Inverters

An inverter is a critical component in the solar energy conversion process, serving the key function of converting the DC current generated by solar panels into AC current that can be used in buildings and fed into the grid. The inverter takes the DC output from the solar panels and uses a rapid switching process to invert the DC power into 240V AC power at the required frequency, typically 50 or 60 Hz depending on the region^[1].

Specifically, the inverter circuitry converts the DC voltage into a square wave, which is a waveform that alternates between the positive and negative DC input voltages. This square wave voltage is then passed through a filter to produce a smooth sinusoidal AC wave. Thus, the inverter enables the DC electricity from solar panels to be compatible with standard AC-based equipment and infrastructure.

Without an inverter, the DC output from solar panels cannot be utilized for most applications. By converting to AC, the inverter allows solar energy systems to connect to the grid, as well as power household appliances, office equipment, factories, and more. Inverters are a key enabling technology for solar PV systems.

[1] https://www.nextpowersolar.com/What-is-the-Function-of-the-Solar-Inverter-id49752647.html

Transformers

Transformers are a critical component in the solar energy production and distribution system. They are used to increase (“step up”) or decrease (“step down”) AC voltage as needed for efficient transmission and distribution (What Is A Solar Transformer?). Step-up transformers increase the AC voltage from solar inverters for transmission along high voltage lines, helping minimize line losses over long distances. They can boost the voltage by 10x or more (for example, from 25kV to 345kV). Custom designed transformers are available from manufacturers like Hitachi Energy for solar installations (Solar Generation Transformers).

Transmission Lines

Transmission lines carry high-voltage AC power from the solar farm to electrical substations. After the electricity is converted to AC power by the inverters, it flows through transformers to increase the voltage. This allows the electricity to travel long distances with minimal power loss. The high-voltage transmission lines are supported by large towers and consist of bundles of wires suspended from insulators. Typical transmission line voltages range from 69 kV to 765 kV.

For example, in India’s Gujarat state, the Gujarat Solar Power Transmission Project involved developing 805 circuit kilometers of 400 kV and 230 kV transmission lines to evacuate power from the Charanka Solar Park to load centers. The project was funded by the Asian Development Bank with the aim of building reliable transmission infrastructure for the successful operation of the solar park.

Substations

A key component in the delivery of electricity from power plants to homes and businesses are substations. As defined by What is an Electrical Substation?, “An electrical substation is a subsidiary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers.”

The main purpose of substations is to transition power from transmission lines to distribution lines. Transmission lines carry electricity at high voltages from power plants to substations, which allows electricity to be transported efficiently over long distances with minimal power losses. At substations, the voltage is stepped down to safer levels for distribution through neighborhoods and cities.

This voltage reduction serves two main functions. First, it prevents dangerous high voltages from reaching homes and businesses. Second, it enables the use of lower capacity, lower cost distribution lines since electricity at lower voltages requires less insulation. Substations contain transformers to reduce electricity to voltages like 120V or 240V for standard household use.

In summary, substations act as the critical intermediary between the transmission and distribution system, enabling the safe and efficient delivery of electricity to end users.

Distribution

After electricity leaves the transmission system, it enters the distribution system. Local distribution lines carry power to homes, businesses, and other customers in local areas (Source 1). The distribution system transforms voltage levels coming from transmission lines to the appropriate level for each customer (Source 2).

Distribution lines carry electricity from substations directly to homes and businesses in the area. Distribution voltage ranges from 2.4 kV to 33 kV. Step-down transformers located at substations reduce the high voltage electricity from transmission lines down to distribution level voltage. From there, distribution lines run along streets above ground or underground to deliver power to customers.

Conclusion

In summary, here are the key steps in how solar energy is converted into electricity and delivered to homes and businesses:

First, sunlight hits the solar photovoltaic panels, causing electrons to be knocked loose from the solar cells. This generates direct current electricity.

The DC power travels from the solar panels to an inverter, which converts it into alternating current that can be used in buildings. Transformers then step up the voltage for efficient transmission over long distances.

The AC power travels over high voltage transmission lines to substations, where transformers step down the voltage for distribution to homes and businesses. This distributed power is then ready for use.

Modern advancements in solar technology, energy storage, microgrids and smart grids will continue to make solar power more affordable, efficient and widespread in the future.