How Does A Solar Panel Work?
A solar panel is made up of solar cells that convert sunlight into electricity through the photovoltaic effect. Photovoltaic cells are made from semiconductor materials such as silicon that release electrons when exposed to photons from sunlight. The electrons flow from the solar panel into an electrical circuit, producing DC current.
The first silicon solar cell was created in 1954 at Bell Laboratories. Through the 1960s, solar panels were mainly used in space applications to provide power aboard spacecraft. It wasn’t until the 1970s that solar power gained traction for commercial and residential uses. Today, solar power is one of the fastest growing renewable energy sources worldwide, supplying just over 3% of global electricity demand.
How Solar Cells Work
Solar cells work by utilizing the photovoltaic effect, the process by which sunlight is directly converted into electricity. Solar cells are made of semiconductors such as silicon, which have a unique ability to absorb sunlight and convert it into electrical current. When sunlight hits the solar cell, the energy knocks electrons loose in the semiconductor material, allowing them to flow freely and produce an electric current.
Specifically, solar cells are made of two types of semiconductors – a p-type with positive charge carriers and an n-type with negative charge carriers. At the interface between the p-type and n-type semiconductors, an electric field forms due to the different charge carriers. When a photon from sunlight hits the solar cell, its energy frees an electron in the p-type semiconductor to move to the n-type semiconductor and flow as electric current. This photovoltaic effect generates voltage and electric power in the solar cell.
Components of a Solar Panel
Solar panels are made up of multiple components that work together to convert sunlight into electricity. The main components of a solar panel include:
Solar Cells
The solar cells are the most important part of a solar panel. They are made up of thin slices of semiconducting material, usually silicon. When sunlight hits the solar cells, the energy from the light is transferred to electrons in the silicon, causing them to flow and produce electricity (source).
Glass Covering
Solar panels are covered by a sheet of tempered glass to provide protection from impact and weather while still allowing sunlight to pass through. The glass covering allows sunlight to reach the solar cells while blocking rain, wind, and other environmental hazards (source).
Frame
Frames provide structural support and rigidity to the solar panel. They are usually made from aluminum which is lightweight, corrosion resistant, and durable. The frames protect the edges of the solar cells and glass covering (source).
Junction Box
The junction box is the output for the solar panel system. It contains terminals to connect the electrical wiring from the solar cells to the other components of the solar system. Junction boxes are weatherproof and house bypass diodes to minimize power loss (source).
Types of Solar Panels
There are three main types of solar panels: monocrystalline, polycrystalline, and thin-film Solar Panel Types – EnergySage.
Monocrystalline solar panels are made from silicon ingots, which are cylindrical in shape. The ingots are then cut into very thin wafers to make the cells. Monocrystalline solar panels have a distinctive look with perfectly square solar cells. These panels have the highest efficiency rates since the cells have a single crystal structure. Monocrystalline panels work better in low light conditions than other types of solar panels. They typically have efficiencies of around 15-22% Types of Solar Panels Guide (2024) – This Old House.
Polycrystalline solar panels are made from square-shaped cells cut from ingots made by melting raw silicon and pouring it into a square mold. The cells have a more bluish color and rounded edges compared to monocrystalline panels. Polycrystalline panels tend to be slightly less efficient than monocrystalline, with typical efficiencies of around 13-17%. However, they are also less expensive to manufacture.
Thin-film solar panels are made by depositing layers of photosensitive materials onto substrates like glass or plastic. Because they use very little solar material, thin-film panels are lightweight and flexible. The main types of thin-film cells are cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and amorphous silicon (a-Si). Thin-film panels have lower efficiencies of around 7-13%, but they can perform well in low light and high temperature conditions.
How Solar Panels Produce Electricity
Solar panels produce direct current (DC) electricity from sunlight, which is the type of electricity produced by batteries. In order to be useful for most household applications, DC electricity from the solar panels needs to be converted into alternating current (AC) electricity, which is the type of electricity delivered over power lines and used by most appliances.
This conversion from DC to AC is done by an inverter. The inverter connects to the solar panels on one side to receive the DC electricity, and connects to the home’s electrical panel on the other side to deliver AC electricity to power the home. Any excess electricity not used by the home can be fed back into the utility power grid.
So in summary, the process is:
- Sunlight hits the solar photovoltaic panels
- Solar panels produce DC electricity
- The inverter converts the DC electricity into AC electricity
- The AC electricity either powers the home or is fed back into the grid
By connecting to the grid via a net metering program, any excess solar electricity can be credited to the homeowner’s energy bill, effectively running the electricity meter backwards and reducing electricity costs.
Factors Affecting Solar Panel Efficiency
There are several factors that can affect the efficiency and performance of solar panels. Some of the main factors include:
Direction and Tilt Angle
The direction that solar panels face and their tilt angle can significantly impact efficiency. Solar panels should generally face true south in the northern hemisphere or true north in the southern hemisphere to maximize exposure to sunlight. The ideal tilt angle depends on the latitude but tilting panels at an angle equal to the latitude will maximize annual energy production 1.
Shading
Any shading on the solar panels, even partial shading, can greatly reduce their output. Solar panels should be installed in a location with no obstructions and full sun exposure throughout the day. Even small amounts of shading from trees, chimneys, or poles can cut energy production 2.
Temperature
Solar panel efficiency decreases as temperature increases. Cooler panels can be 10-25% more efficient than hot panels. Proper air flow and ventilation around the panels can help keep temperatures lower 3.
Sizing and Installing Solar Panels
Properly sizing and installing solar panels are critical steps in the solar energy process. The key considerations when sizing solar panels include assessing your household’s electricity needs, optimal solar panel placement, and wiring the panels to your electrical system.
First, calculate your home’s energy requirements. Review 12 months of previous electric bills to determine your average monthly usage in kilowatt-hours (kWh). Factors like household size, appliances used, and energy efficiency measures will impact energy needs. Once you know your average electricity usage, you can properly size your solar panel system to match your requirements.Homeowner’s Guide to Going Solar
Next, determine the optimal placement for solar panels. South-facing rooftops without obstructions like chimneys or trees are ideal. Panels should be tilted at an angle equaling your latitude for maximum sunlight exposure. Consider possible shading issues from nearby trees and buildings throughout the day and seasons. Proper placement is key for solar panel productivity.
Finally, wiring is needed to connect the solar panels to your home’s electrical system. If your system is grid-tied, you’ll need wiring to link the solar array to the utility grid via an inverter and net meter. For off-grid systems, wire the panels to a battery bank for energy storage and an inverter for AC power. Engage a solar installer for assessing your wiring needs and hooking up the panels safely and efficiently.How to Install Solar Panels In 2024
Maintenance of Solar Panels
Regular maintenance is important for solar panels to keep performing optimally and producing maximum energy output. The maintenance activities primarily involve inspecting, cleaning, and repairing the solar panels.
Cleaning solar panels is recommended at least twice a year, but ideally every few months [1]. Dust, dirt, bird droppings, pollen and other debris on the panels can reduce their efficiency. Panels can be gently cleaned with a soft brush, microfiber cloth, or low pressure water. Harsh chemicals should be avoided. Take care not to scratch the glass when cleaning.
Inspections should be conducted along with cleaning to check for any damage, wear and tear, or issues. Check electrical connections, wires, and the inverter for any problems. Also inspect the mounting structure and panels for any loose parts, cracks, or corrosion. Early detection of minor issues can help avoid bigger problems down the line.
Any noted faults, damage or wiring issues should be repaired by a qualified solar technician to maintain safety and performance. Major panel damage may require replacing the panel. Regular inspections and maintenance helps minimize the need for repairs.
Proper maintenance as per the manufacturer’s recommendations helps solar panels perform optimally for their 25+ year lifetime.
Cost of Solar Panels
The cost of solar panels can vary greatly depending on the size of the system, equipment, installation, incentives, and location. The main costs associated with solar panels are the equipment costs and installation costs.
For equipment costs, the solar panels themselves make up about 40% of the total system cost. In addition to the panels, costs for inverters, racking, wiring, and other electrical equipment make up the remaining equipment expenses. According to Forbes, the average cost for solar panels in 2023 is around $16,000 for a 6 kW system before incentives.
Installation costs account for about 40% of the total solar panel system cost as well. This includes labor, permitting fees, and any additional structural upgrades needed during installation. Typical installation costs range from $2,500 to $5,500 depending on system size and complexity.
There are also financial incentives that can offset the upfront costs of solar panels. These include federal tax credits, state/local rebates, solar renewable energy certificates (SRECs), and net metering savings. The federal solar tax credit is 26% of system costs for 2023 and can drop the net price significantly.
Overall, solar panel costs can vary from $15,000-$40,000+ for a typical home installation. Costs are continuing to decline year over year, making solar more affordable for homeowners nationwide. Carefully calculating the long-term return on investment along with available financial incentives helps determine the total value proposition of installing a solar PV system.
Environmental Impact
Solar panels can have both positive and negative impacts on the environment. On the positive side, solar panels produce clean, renewable energy without emitting greenhouse gases or air pollution. According to the Union of Concerned Scientists, solar photovoltaic systems generate electricity with no global warming emissions during operation and very low emissions during manufacturing (source). The U.S. Energy Information Administration states that solar energy technologies do not produce air pollution or greenhouse gases when operating (source).
However, solar panels do have some negative environmental impacts to consider. Producing solar panels requires energy and resources, and some hazardous materials like cadmium and lead are used. There are concerns around the end-of-life disposal of solar panels, which could potentially leach metals into landfills. Proper recycling is important to prevent negative impacts. According to the Harvard Business Review, some governments classify solar panels as hazardous waste due to the heavy metals they contain (source). Overall, the carbon footprint of solar panel manufacturing is small compared to the clean energy generated over their lifetime.
