Essential Solar Panel System Vocabulary

Current

A flow of electrical charge carried through wires. Learn more about its types under AC and DC.

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The Basics of AC Power

DC (direct current) refers to the flow of electrical current in one direction. This is the type of current generated by solar panels and other renewable energy sources. When DC energy is generated, it needs to be converted to AC (alternating current) to be used by household appliances and electrical devices, as AC is the standard type of current in most U.S. households. An inverter is used to facilitate this conversion, allowing the energy produced by solar panels to be used efficiently within the home.

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Direct Current (DC)

This refers to the type of electrical current an electrical device uses. Alternating Current (AC) is the form of current used in our homes and businesses. It alternates direction periodically, making it efficient for long-distance power transmission. On the other hand, Direct Current (DC) flows in one direction and is commonly produced by solar panels and batteries. DC must be converted to AC through an inverter to power our homes using electricity from solar panels. When discussing the power (in watts or kW) of solar, we're referring to the DC output. However, after conversion to AC, the resulting AC output is typically 15%-20% less than the original DC output due to inefficiencies in the conversion process.

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Light Reflection Angles

The angle of incidence refers to the angle between a ray of sunlight and a line perpendicular to a solar panel's surface. When the angle of incidence is 0 degrees, the sunlight strikes the panel directly, allowing for maximum energy production. At sunrise and sunset, the angle of incidence approaches 90 degrees, which means the sunlight is hitting the panel at a lower angle and results in less energy generation. In general, the closer the angle of incidence is to 0 degrees, the more effective the panel is at converting sunlight into energy.

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Exploring the Role of CO2 in the Atmosphere and Beyond

Solar energy is a clean and renewable source of energy that can significantly reduce carbon emissions compared to fossil fuel-based power sources. By installing solar panels, you can generate your own electricity and reduce your dependence on the utility grid. This not only lowers your carbon footprint but also contributes to the global effort to combat climate change. With solar energy, you can harness the power of the sun to power your home or business, leading to a more sustainable and eco-friendly lifestyle.

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Shared Solar Energy Projects

Community solar is an innovative approach that enables multiple individuals within a community to collectively invest in a shared solar system. This arrangement allows utility customers who are unable to install solar panels on their own property to participate in the benefits of solar energy. While the integration of community solar with existing utility systems is still being refined in some regions, other areas have already successfully implemented community solar programs. By participating in such a program, community members can potentially reduce their electricity costs and contribute to the reduction of carbon emissions for the entire community.

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Scattered Solar Radiation

This sunlight refers to the indirect light received as it passes through clouds, haze, fog, or other atmospheric obstructions. Although not as efficient as direct insolation in generating energy, diffuse insolation can still contribute to energy production. Monocrystalline solar cells are optimal for capturing and converting diffuse insolation into electricity effectively.

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Rectifier

A diode is a device that allows electricity to flow in one direction while blocking it in the opposite direction. In solar systems, diodes are commonly used to prevent energy from being sent back to the solar panels when they are not generating electricity. This helps protect the panels and maintain the efficiency of the system. By controlling the flow of electricity, diodes play a crucial role in safeguarding the solar setup and ensuring smooth operation.

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Direct Exposure

This refers to the amount of direct sunlight that reaches a specific area on Earth's surface. It is calculated by starting with the solar irradiance that strikes the atmosphere and then subtracting the amount of sunlight lost due to atmospheric absorption and scattering.

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Flow of Electric Charge

This is the movement of electrical charge. The charge arises from electrons traveling through a conductor such as a wire.

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A Comprehensive Audit

Energy audits are conducted on buildings to assess their energy consumption and identify opportunities for efficiency improvements. These audits take place during the construction phase to ensure compliance with municipal regulations and later on when building owners seek to reduce energy consumption. Homeowners commonly request these audits to gain insight into their energy usage and explore potential upgrades that can lead to cost savings and improved energy efficiency.

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An Overview of Fossil Fuels

Coal, oil, and natural gas are the primary fossil fuels used to generate energy in today's world. These resources have developed naturally over millions of years. However, burning them for energy releases large quantities of pollutants into the atmosphere, significantly contributing to climate change. In contrast, solar energy harnesses the power of the sun directly, offering a clean energy source that does not rely on burning fossil fuels and helps mitigate the effects of global warming.

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Full Sun

The peak intensity of sunlight striking a surface occurs at midday, representing the highest level of energy that a system can harness. This maximum irradiation corresponds to the potential maximum output of the system in terms of energy generation or performance.

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Grounding Essentials

Grounding is an essential safety measure in solar systems, where metal components are connected to the ground to prevent electrical hazards. This involves attaching conductive parts of the solar system to a designated ground, ensuring that the voltage is effectively neutralized and that any electrical charges are safely dissipated. This process helps protect against the risk of electric shock or fire by stabilizing the voltage in the system and ensuring it remains at safe levels.

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GW or Gigawatt

A gigawatt is a substantial unit of power, equivalent to 1 billion watts. This measurement is also equal to 1 million kilowatts or 1 thousand megawatts. It represents a large-scale output that is commonly used to measure the generation capabilities of power plants and other significant energy-producing facilities.

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Incident Light

When sunlight falls upon the surface of a solar module, it initiates a process of energy transformation that is both remarkable and crucial for sustainable power generation. The sun's radiant energy interacts with the photovoltaic cells, exciting the electrons within and creating an electrical current. This seamless conversion of sunlight into electricity not only powers our homes and devices but also represents a cleaner, greener future for energy production. By harnessing the sun's rays, we unlock a resource that is both abundant and renewable, paving the way for a more sustainable approach to meeting the world's energy demands.

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Insolation

Solar power density, often referred to as solar irradiance, is a measure of the amount of solar energy received on a surface over a period of time. It is measured in watts per square meter (W/m²). This metric helps in understanding how much solar energy can be harnessed at a specific location and time, and is crucial for evaluating the efficiency and effectiveness of solar panels and other solar energy systems.

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Irradiance

Insolation is the cumulative amount of solar energy that reaches a surface over a specific period, combining direct sunlight, scattered or diffused rays, and reflections from other surfaces. When irradiance is measured over a period of time, it results in a quantity known as insolation.

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Legal Authority

The governing body that oversees the administration of justice operates across different levels, including state, national, and local jurisdictions such as townships or cities. In the context of solar energy, the local jurisdiction is responsible for determining the requirements and guidelines for obtaining construction permits. These solar permitting laws can differ significantly depending on the local authority and must be considered when planning solar installations.

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Kilowatt (kW)

A unit of power equal to 1,000 watts.

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Kilowatt-hour (kWh)

A measure of energy equal to 1,000 watts consumed over 1 hour.

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Latitude

Latitude defines the north-south location on Earth's surface. The Equator is at 0 degrees latitude, while the North Pole is at 90 degrees latitude. The higher the latitude, the less sunlight reaches the Earth's surface throughout the year. As a result, solar systems located closer to the equator tend to generate more energy compared to those farther north, given equal conditions. Additionally, your location's latitude will determine the optimal angle for tilting your solar panels. The further north you are, the steeper the ideal tilt angle for maximizing solar energy absorption.

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Longitude

Longitude specifies a location on Earth east or west of Greenwich, England. While your longitude doesn't directly affect your solar energy production, it does determine the local time of solar noon. Solar noon is when the sun is at its highest point in the sky, which is relevant for solar panel alignment and potential energy capture. Latitude, on the other hand, is a key factor in optimizing solar production as it influences the sun's angle and path throughout the day.

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Megawatt (MW)

A unit of power equal to 1 million watts or 1,000 kilowatts.

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Net Metering: Balancing Energy Usage and Production

A system that connects individual solar systems to the public utility grid allows solar energy to be integrated into the broader power network. These solar installations can send excess energy back to the grid, earning the individual credits for the surplus energy. These credits can then be used to offset future energy consumption, enabling the user to pay only for the "net" energy usage. This approach provides a balanced and efficient use of solar power while maintaining a connection to the main power grid.

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The Basics of Open Circuit Voltage (VOC)

The open-circuit voltage (VOC) represents the maximum voltage output a solar panel or system can produce when there is no load connected (current is zero). This voltage increases as the temperature of the solar equipment decreases. It is crucial for the VOC to remain below the inverter's maximum input voltage to avoid potential damage to the inverter.

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Parallel Electrical Circuits

An electrical circuit with multiple paths for the current to flow is known as a parallel circuit. In a solar energy system, micro-inverters establish a parallel circuit, ensuring that each solar panel operates independently. This setup enhances the overall performance and efficiency of the system by protecting against the reduced output of a single panel. On the other hand, a string inverter configures the system in a series circuit, where the panels are connected in a single line and the performance of the system is limited by the least efficient panel.

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The Passive Solar Home Approach

This is a dwelling specifically constructed to harness the sun's energy throughout the year. In winter, its features such as walls, windows, and floors capture and store solar energy to provide warmth. In summer, these same elements are designed to block out excessive sunlight, maintaining a cooler indoor environment. This approach ensures efficient temperature regulation in the home, utilizing natural solar power for passive heating and cooling.

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Photons

Particles that are carried through sun rays and essentially produce solar energy.

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Solar Photovoltaic Technology

A photovoltaic system (also known as a PV system or solar system) converts sunlight into electricity through the process of exciting electrons with photons. This energy transfer creates an electric current, enabling the system to generate power from the sun.

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Energy Conversion and Efficiency.

The proportion of sunlight that is transformed into electrical energy by a solar panel is known as its efficiency. Any remaining energy is dissipated through other channels, such as light that is reflected away or lost as heat. The overall efficiency of a solar panel is critical, as it dictates the amount of energy that can be generated per unit area of the panel.

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Sustainable Energy Solutions

Renewable energy sources derive their energy from the sun, making them sustainable and environmentally friendly. These sources include solar power, wind energy, geothermal, biomass, and tidal power, all of which rely on the sun either directly or indirectly. These forms of energy are continually replenished by the sun, ensuring a consistent and clean supply. Their use produces minimal to no carbon emissions, offering a green alternative to fossil fuels and contributing to the reduction of global carbon footprints.

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Series Circuit

An electrical circuit with only one path for the flow of electric current is known as a series circuit. In this type of circuit, all the components are connected end-to-end, forming a single loop through which current can flow. This arrangement is common in string inverters in solar systems, where the strings are wired in series. A clear example of a series circuit can be seen in a strand of typical Christmas lights; when one light in the series goes out, the entire strand stops working. This is because the current can no longer pass through the broken light. In contrast, if each light bulb were connected in parallel, the remaining bulbs would continue to function even if one goes out.

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Silicon

This is a material found in solar cells that facilitates the generation of electrical energy from sunlight through the photovoltaic effect. The base material for all PV cells is silicon, a semiconductor that plays a crucial role in converting solar energy into electricity.

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Solar Cell or PV Cell

Solar panels convert sunlight into electricity using photovoltaic cells. These panels consist of numerous solar cells, typically arranged in configurations of either 60 or 72 cells. The solar cells are usually made from silicon, which can be either monocrystalline or polycrystalline. Monocrystalline cells are known for their uniform appearance and high efficiency, while polycrystalline cells are slightly less efficient but often more cost-effective.

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Solar Noon

The point of time during the day that the sun is at its highest point in the sky. The time of solar noon is dependent on the longitude of a location.

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Solar Photovoltaics or Solar Cells

Turn sunlight into electricity through the photovoltaic effect.

Solar Power Plant

Much like a coal, nuclear, or natural gas power plant, but entirely powered by sunlight. A solar power plant can be composed of either solar photovoltaics or through heating steam through a combustion engine. Every home that puts solar on their roof creates their own solar power plant.

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Solar Radiation

Solar energy refers to the radiant energy emitted by the sun, which encompasses a broad spectrum of radiation. This includes visible light, which illuminates the world, as well as ultraviolet rays that can cause sunburn. The sun's energy is a crucial source for life on Earth, providing heat, light, and power for various natural and human activities.

Solar Spectrum

The solar spectrum encompasses the full range of electromagnetic waves emitted by the sun. The wavelength of these waves determines the form of energy they carry, whether it manifests as visible light or ultraviolet radiation.

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Solar Thermal

Solar thermal technology harnesses the energy of the sun's rays to heat fluids. Initially popularized in the 1970s as a method for heating water in homes, its use has since grown to include heating pools as well. In addition, larger-scale solar thermal power plants utilize this technology to heat fluids and produce steam, which in turn drives turbines to generate electricity.

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Transformer

This is a transformer, an electrical device that is used to adjust voltages in various applications such as appliances, power lines, and other electrical systems. Transformers can either increase (step-up) or decrease (step-down) voltages, ensuring that the appropriate voltage levels are delivered to different parts of an electrical circuit for safe and efficient operation.

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True South

True south is the direction directly opposite to the sun at solar noon, unlike magnetic south which varies depending on geographic location. To determine true south, you need to establish when the sun is at its highest point in the sky. Solar systems function most efficiently when oriented toward true south.

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Utility

When relating to solar, we speak of Utilities as the source that delivers you electricity. Your utility might also deliver water and natural gas. Your Utility maintains your power lines, balances the grid’s load, and generates or procures electricity.

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VAC

This pertains to the AC voltage. U.S. homes have sockets that are between 110 and 120 VAC.

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VDC

This pertains to the DC voltage. Most batteries run at 12 VDC.

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VMP or Voltage Maximum Power

This refers to the voltage of a solar panel at maximum output current with ideal conditions.

Voltage

This is the electric potential between two points, measured in volts.

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Volts

A unit of electrical force that will cause one a current of one amp to move through a resistance of one ohm.

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Watt (W)

The rate of energy transfer over time is measured in joules per second, which is equivalent to one watt. A standard light bulb, for instance, typically consumes between 40 and 60 watts of power.

Watt-hour or (Wh)

One watt-hour (Wh) is a unit of energy that represents the consumption of one watt of power over a duration of one hour. For example, if a 40-watt light bulb is used for one hour, it will consume 40 watt-hours of energy.

Zero Net Energy

This refers to a building that produces the same amount of renewable energy that it consumes.

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