Glossary

Solar Terminology

Activated Shelf Life: The length of time at a specific temperature that a charged battery can be stored before it’s electric capacity runs out.

Alternating Current: (AC) electricity type commonly used by households and businesses. Alternating current reverses direction at regular intervals. Direct Rays from the sun must be converted to AC before it is used in homes and businesses.

Ambient Temperature: The temperature of a surrounding area.

Ampere: (amp) The rate of flow of electrons that are considered a unit of electric current. One volt across one ohm of resistance causes the current flow on one ampere.

Angle of Incidence: The angle a ray of sunlight makes with a line perpendicular (90 degrees) to a surface. A solar panel that directly faces the sun has an angle of incidence of zero.

Annual Solar Savings: Energy savings from solar features on a building compared to energy requirements of non-solar building.

Anode: Positive electrode in a battery or the ground in a cathodic protection system.

Array Current: Electric current that a photovoltaic array produces when exposed to the sun.

Array Operating Voltage: Voltage produced bay a photovoltaic system when exposed to sunlight and is connected to a load.

Azimuth: The orientation, or direction, your property faces. It can be measured from 0°:360°. Ideal solar systems in Delaware will face 180° south to receive the maximum amount of sunlight.

Balance of System: All components and costs other than the photovoltaic array such as design, land, site preparation, installation, maintenance, storage, power conditioning, support structures, operation, and related costs.

Battery Backup: Rechargeable devices that can be installed in conjunction with a solar system to capture and store excess energy generated by a solar system. Battery backups can also be known as solar batteries or solar storage.

Battery Capacity: The maximum total electrical charge which a battery can deliver to a load under specific conditions.

Battery Cell: Single unit in an electrochemical device with the ability to produce direct voltage by converting chemical energy into electrical energy.

Battery Energy Storage: Energy that is stored using a electrochemical battery.

Battery Life: The period a cell or battery can operate above an efficiency performance level or capacity before it fails.

Charge: The process of adding electrical energy to a battery.

Charge Controller: A component of a photovoltaic system that controls flow of current to and from a battery to protect it from over discharge or over charging. Sometimes it indicates the amount of charge left.

Cost Analysis: The close look at labor, time and resources required before a solar project can begin.

Cycle: A discharge and recharge of a battery.

Direct Current: Energy that flows in one direction through a conductor. Opposite of Alternating current used in buildings.

Distribution: Transference of electricity over short distances through cables into homes or businesses.

Efficiency: Rating ability to covers sunlight into useable electricity

Electrical Grid: A system of electricity distribution by a utility company that covers a large area.

Electricity: Energy created from the flow of charged particles.

Electricity Consumers: People that purchase and use electricity.

Electricity Retailers: Businesses that sell electricity to consumers in a deregulated electricity market.

Electric Utility: Private or public entities that own and operate the powerlines that transport electricity.

Energy: The capability of doing work; energy can be transformed into other forms of energy, but the total amount of energy remains the same.

Energy Audit: Survey of a building that reveals how much energy is used then identifies ways to use less electricity.

Fixed Tilt Array: A photovoltaic array set up to a fixed angle in relation to the horizon.

Frequency: Repetitions per unit of time of a waveform, expressed in Hertz (Hz).

Full Sun: The power of sunlight received on the Earth’s surface at noon on a clear day.

Generation: Process of converting energy to electricity. This is done via renewable sources such as solar, wind and hydroelectric power; nuclear plants or power plants that generate electricity from fossil fuels such as coal, oil and natural gas.

Generators: Powerplants used to generate electricity.

Gigawatt: 1 Gigawatt (GW) =1,000 Megawatts

Grid: The grid is what utility companies use to transfer electricity to customers. It is a network of powerlines, transformers and other equipment that powers a region. Modern grids allow people to make and sell their own energy.

Ground-Mounted solar: A solar system that is installed on a plot of land and not on a roof. Most large-scale commercial systems and community solar systems are ground mounted.

Home Energy Auditor: A trained professional that can identify areas of a home or business that are costing them money in higher utility bills. Auditors identify and make suggestions of ways to improve energy efficiency.

Input Voltage: Total power required by the alternating current loads and voltage of any direct current loads. The larger the load, the higher the inverter input voltage.

Installer: The qualified individual or company that installs the solar system at your property.

Interconnections: Expansive grids across large regions of the U.S. that are not connected. Electricity does not flow between the large interconnections.

Interconnection agreement: The agreement between a solar system owner and their utility that allows the system owner to connect their solar system to the utility grid.

Inverter: A solar inverter takes direct current (DC) electricity from the solar system and converts it to alternating current (AC) electricity that is usable. Inverters can be tiny or as large as a truck.

Kilowatt: A standard unit of electrical power. 1 Kilowatt (kW) =1000 Watts. Number of panels x watts per panel give you the kilowatts of a system.

Kilowatt-Hour (KWh): A thousand watts acting over a period of an hour.

Life: The length of time a photovoltaic system above a specified performance level.

Life Cycle Cost: Estimated cost of owning and operating a photovoltaic system for the period of its life.

Load: Sometimes called demand, it is the amount of electricity appliances use in your home or business. For example: Heating and Air Conditioning units (HVAC) and refrigerators and hot water heaters use more electricity or load than a television. Some homeowners may have a smart panel to control the load of appliances in the home at specific times of the day. Like shedding loads at nighttime.

Megawatt: Measure of a power plant generating capacity. 1 Megawatt (MW) = 1000 Kilowatts = 1 million watts.

Net-Metering: A utility billing functionality offering credit on your electric bill for excess solar energy generated by your system that is not used to power your home.

One-Axis Tracking: A system capable of rotating about one axis.

On grid/Off grid Systems: A solar array with battery backup that is not connected to the electric grid and supplies electricity when the grid goes down. Solar panels collect solar radiation and covert it to Direct Current (DC). Inverters connected to the panels convert energy to AC. When needed off grid inverters can convert the AC from the exterior inverters back to DC and store it in a battery backup system. When electricity stored in the battery is needed the interior inverters convert the DC back to AC to use in the house or building. Homeowner may have a backup generator attached to this type of system to provide power when batteries are drained. Large backup systems can cost many thousands of dollars.

To have a whole home back up system you may need the following: a separate room for system and batteries. Because batteries are very heavy you may need to increase floor support. The room should also have a form of temperature control.

Panel Degradation: The reduction of a solar panels output over time. Solar panels have a 0.5% degradation rate per year. Check the manufacturers warranty on the panels – most will say your panels will be at 85% in year 25.

Parallel Connection: Joining solar cells or modules with positive leads

Perovskite: A calcium titanium oxide mineral found in the Earth’s mantle that is used in solar cells. It is named after a Russian mineralogist.

Perovskite Solar Cell: Type of thin:film solar cell that includes a perovskite structured compound built with layers of materials that are printed, coated or vacuum deposited onto a substrate. Cells can produce energy at a lower rate per kW than silicon made cells. They can capture wavelengths of light and convert them to electricity that silicon cells cannot.

Photovoltaics (PV): The sun’s energy or light, shines on solar panels. The photovoltaic manmade cells in the panels convert light energy into electrical charges that continue to move creating electricity. Solar systems are frequently referred to as solar photovoltaic, or solar PV, systems.

Photovoltaic (PV) Array: Connected PV modules that function as a single electric producing unit. Modules have a common support or mounting system.

Power Purchase Agreement (PPA): A financial arrangement in which a third:party developer owns, operates, and maintains a solar system. The host customer agrees to site the system on its property and purchases the system’s electric output from the solar services provider for a predetermined price.

Reverse Current Protection: Method of preventing unwanted current flow form battery to photovoltaic array.

Silicon: An abundant element (Si) found everywhere. Refined by a chemical process it is converted into crystalline silicon which conducts electricity.

Solar Array: Multiple solar panels wired together form a solar array.

Solar Cell: One small unit of a solar panel strung together with other cells that create a module or panel. Modules are connected together to make a solar array or system.

Solar Energy: Solar radiation or electromagnetic energy transmitted from the sun.

Solar Lease: A financial arrangement in which a third-party developer owns and maintains a solar system. The host customer agrees to site the system on its property and pays a monthly fee to system owner in exchange for all of the electricity produced by the system.

Solar Nuclear Fusion: The sun releases energy that solar panels use to produce electricity. The sun has hydrogen atoms that are fused to create helium which is responsible for the energy the sun emits.

Solar Panel: A collection of solar cells that are connected to each other.

Solar Power: Energy from the sun that is converted into electrical or thermal energy.

Solar Renewable Energy Credits (SRECs): Credits generated by a solar system based on the electricity produced by the system. One SREC is generated for every megawatt hour (MWh), or 1,000 kilowatt hours (kWh), of electricity generated by a solar system.

Standard Test Conditions: Testing done by manufactures 25 degree Celsius, 1000 watts per metered² of sunlight hitting the panels. It varies depending on the amount of sunlight and conditions of light hitting panels. Temperatures also cause panel out to vary.

Transformer: Electricity is transferred at high voltages to minimize the loss as it travels over the miles. A transformer is needed to decrease voltage levels used by homes and businesses.

Transmission: Power plants transport electricity over long distances from where it is generated to the end users of electric energy.

Tilt: The slant or slope of your roof. The best tilt for solar panels is between 30° and 45° from horizontal (flat). When solar panels are installed on your roof, they will follow the tilt of your roof.

Tilt Angle: The angle that a photovoltaic array is set to face the sun relative to a horizontal position.

Tracking Array: Photovoltaic array that follows the path of the sun to make best use of the solar radiation on the PV surface.

Utility Grid: The interconnected network of power lines, transformers, energy generators, etc. that delivers electricity to your home or business. This is also referred to as the power grid or electrical grid.

Vertical Integrated Utilities: Electric utilities that own and produce at powerplants then transmit and distribute electricity in the area they serve.

Volt: Amount of electromotive force that exists between two points.

People to know:

Asset Owner: The entity that owns a community solar project.

Developer: The entity that builds the community solar project.

Subscriber Aggregator: Sales organization that sources subscribers for Community Solar projects. The subscriber aggregator may present a Community Solar Subscription Agreement which will have a clause that the subscription can be sold to another entity.

Subscription Manager: The organization in charge of the administration of a solar project, including handling subscriptions, billing, and contracts. Some asset owners manage subscriptions inhouse and other outsource to third-party subscription managers with whom you will interact with instead.

Community Solar Subscription: A subscription plan to an offsite community solar project that allows homeowners, renters, small businesses, schools, and other nonprofits to support clean, renewable solar energy without the need to purchase a solar array or install rooftop panels on their property.

Subscription Fees: The subscription fee is a charge by the Community Solar Subscription Agreement owner which could be your Subscriber Manager or the Community Solar project owner. The fee reflects the monthly cost to subscribe to the solar project.

Agency: Some Community Solar subscription agreements have a stipulation that the contract owner has the right to adjust your subscription or move your subscription to a new project without needing consent ahead of time.

Subscription Size (kW) is based on your annual household electricity consumption.

Solar Production (kWh) is the amount of electricity production from the solar project that corresponds to the proportion of the total project that you’ve subscribed to.

Percent Savings are calculated as your annual solar savings divided by your annual electricity costs.

Bill Credits: The bill credit rate is the amount in dollars that participants receive from their electric utility for the electricity generated by their subscription.

Bill Savings: Calculated as the difference between bill credits and subscription fees.

Subscriber: a customer who is signed up for/subscribed to a community solar project.