A
AC Coupling
Inverters & Charge Controllers
AC coupling is a system architecture where the solar panels and battery storage each have their own separate inverter, a...
AGM
Battery Storage
AGM stands for Absorbent Glass Mat, a sealed lead-acid battery design that suspends the sulfuric acid electrolyte in fib...
Amp-Hour (Ah)
Battery Storage
An amp-hour (Ah) is a unit of electrical charge that measures a battery's storage capacity in terms of current delivery ...
Azimuth
Installation
Azimuth is the compass direction a solar panel faces, measured in degrees from true north. Due south is 180° azimuth, du...
B
Ballasted Mount
Installation
A ballasted mount is a solar panel racking system that uses heavy weights — typically concrete blocks or precast concret...
Battery Bank
Battery Storage
A battery bank is a group of individual batteries connected together to form a single energy storage unit with the desir...
Battery Management System (BMS)
Battery Storage
A battery management system (BMS) is an electronic circuit board built into lithium batteries that monitors cell health ...
Bifacial Panel
Panel Technology
Bifacial solar panels generate electricity from both the front and rear sides of the module. The front captures direct a...
Blocking Diode
Electrical Fundamentals
A blocking diode is placed in the circuit between a solar panel (or panel string) and a battery bank to prevent reverse ...
Bulk Charge
Battery Storage
Bulk charge is the first stage of the multi-stage battery charging process, where the charge controller or charger deliv...
Bypass Diode
Electrical Fundamentals
A bypass diode is a small semiconductor device installed inside a solar panel's junction box that provides an alternate ...
C
Cell Efficiency
Panel Technology
Cell efficiency is the percentage of sunlight energy hitting a solar cell that gets converted into electrical energy. It...
Combiner Box
Electrical Fundamentals
A combiner box is an electrical enclosure that merges multiple parallel solar panel strings into a single output feed be...
Community Solar
Incentives & Policy
Community solar (also called shared solar or solar gardens) allows people to benefit from solar energy without installin...
Cost Per Watt
Financial
Cost per watt is the most common metric for comparing solar system prices across different sizes, configurations, and in...
Cycle Life
Battery Storage
Cycle life is the total number of complete charge-discharge cycles a battery can perform before its capacity degrades to...
D
Degradation Rate
Panel Technology
Degradation rate is the percentage of power output a solar panel loses each year due to natural aging processes. All sol...
Degradation Warranty
Financial
A degradation warranty is the portion of a solar panel's performance guarantee that specifies the maximum allowable annu...
Depth of Discharge (DoD)
Battery Storage
Depth of discharge (DoD) is the percentage of a battery's total capacity that has been used. If a 100Ah battery has deli...
E
Energy Offset
Financial
Energy offset is the percentage of your total electricity consumption that is replaced by solar production. A 100% energ...
Equalization Charge
Battery Storage
An equalization charge is a controlled, intentional overcharge applied to flooded lead-acid batteries that raises the ch...
F
Feed-in Tariff
Incentives & Policy
A feed-in tariff (FIT) is a policy mechanism that pays solar system owners a guaranteed, fixed rate for every kilowatt-h...
Fill Factor
Electrical Fundamentals
Fill factor (FF) is a measure of a solar cell's quality that describes how closely its IV curve approaches an ideal rect...
Float Charge
Battery Storage
Float charge is the final stage of the multi-stage battery charging process. After the battery reaches full charge throu...
G
Gel Battery
Battery Storage
Gel batteries are a sealed lead-acid design that uses a thickened electrolyte — sulfuric acid mixed with fumed silica to...
Grid Parity
Financial
Grid parity is the point at which the cost of generating electricity from solar panels equals the cost of purchasing ele...
Grid-Interactive
System Types
A grid-interactive solar system is functionally similar to a hybrid system — it connects to the utility grid, incorporat...
Grid-Tie Inverter
Inverters & Charge Controllers
A grid-tie inverter converts DC electricity from solar panels into AC electricity synchronized with the utility grid, en...
Grid-Tied System
System Types
A grid-tied solar system connects directly to the utility grid through a grid-tie inverter, allowing you to use solar po...
Ground Mount
Installation
Ground mount installations secure solar panels on a freestanding structure built at ground level, using posts driven int...
H
Half-Cut Cell
Panel Technology
Half-cut cell panels use solar cells that have been precisely laser-cut in half before being wired into the module. A st...
HJT
Panel Technology
HJT stands for Heterojunction Technology, a solar cell design that sandwiches a crystalline silicon wafer between thin l...
Hybrid Inverter
Inverters & Charge Controllers
A hybrid inverter combines the functions of a grid-tie solar inverter, a battery charger, and a battery inverter in a si...
Hybrid System
System Types
A hybrid solar system combines grid connection with battery storage, giving you the financial benefits of net metering a...
I
IBC Cell
Panel Technology
IBC stands for Interdigitated Back Contact, a premium solar cell design that moves all electrical contacts to the rear s...
Interconnection Agreement
Incentives & Policy
An interconnection agreement is a formal contract between a solar system owner and the local utility that establishes th...
Investment Tax Credit (ITC)
Incentives & Policy
The Investment Tax Credit (ITC), also known as the federal solar tax credit, is a dollar-for-dollar reduction in your fe...
IV Curve
Electrical Fundamentals
An IV curve (current-voltage curve) is a graph that plots all possible operating points of a solar panel by mapping the ...
L
Lead-Acid
Battery Storage
Lead-acid batteries are the oldest rechargeable battery technology, invented in 1859, and have been the workhorse of off...
Levelized Cost of Energy (LCOE)
Financial
Levelized cost of energy (LCOE) is the total lifetime cost of a solar system divided by the total lifetime energy it pro...
Lithium Iron Phosphate (LiFePO4)
Battery Storage
Lithium iron phosphate (LiFePO4 or LFP) is a lithium-ion battery chemistry that has become the dominant choice for solar...
M
Maximum Power Point (MPP)
Electrical Fundamentals
The maximum power point (MPP) is the specific combination of voltage and current at which a solar panel produces its hig...
Microinverter
Inverters & Charge Controllers
A microinverter is a small inverter mounted directly behind each individual solar panel, converting DC to AC at the pane...
Microinverter Rapid Shutdown
Installation
Microinverter rapid shutdown refers to the inherent safety advantage of microinverter systems in meeting NEC module-leve...
Modified Sine Wave
Inverters & Charge Controllers
Modified sine wave (MSW) is a stepped approximation of a true sine wave produced by cheaper inverters. Instead of the sm...
Module Efficiency
Panel Technology
Module efficiency is the percentage of sunlight energy striking the entire surface area of a finished solar panel that g...
Monocrystalline
Panel Technology
Monocrystalline solar panels are made from single-crystal silicon ingots sliced into thin wafers. The manufacturing proc...
MPPT
Electrical Fundamentals
MPPT stands for Maximum Power Point Tracking, an electronic technique used by solar charge controllers and inverters to ...
MPPT Charge Controller
Inverters & Charge Controllers
An MPPT charge controller is a sophisticated DC-to-DC converter that sits between your solar panels and battery bank, pe...
N
O
Off-Grid Inverter
Inverters & Charge Controllers
An off-grid inverter converts DC power from a battery bank into AC electricity for household use in a system that operat...
Off-Grid System
System Types
An off-grid solar system operates completely independently of the utility grid, generating, storing, and managing all of...
Open-Circuit Voltage (Voc)
Electrical Fundamentals
Open-circuit voltage (Voc) is the maximum voltage a solar panel produces when no current is flowing — that is, when the ...
P
Parallel Wiring
Electrical Fundamentals
Parallel wiring connects solar panels side-by-side by linking all positive terminals together and all negative terminals...
Payback Period
Financial
The payback period is the number of years it takes for a solar system's cumulative energy savings to equal the net cost ...
Peak Sun Hours
Installation
Peak sun hours (PSH) is a standardized way to express the total daily solar energy at a location as the equivalent numbe...
PERC Cell
Panel Technology
PERC stands for Passivated Emitter and Rear Cell (sometimes Rear Contact). It is an enhancement to standard silicon sola...
Performance Guarantee
Financial
A performance guarantee is a contractual commitment from a solar panel manufacturer specifying the minimum power output ...
Photovoltaic Effect
Electrical Fundamentals
The photovoltaic effect is the physical phenomenon that makes solar panels work. When photons (particles of light) strik...
Polycrystalline
Panel Technology
Polycrystalline solar panels are manufactured by melting raw silicon and pouring it into a square mold, where it cools a...
Power Optimizer
Inverters & Charge Controllers
A power optimizer is a DC-to-DC converter mounted behind each solar panel that performs panel-level MPPT optimization wh...
Power Purchase Agreement (PPA)
Incentives & Policy
A power purchase agreement (PPA) is a financial arrangement where a third-party developer installs, owns, and maintains ...
Production Guarantee
Financial
A production guarantee is a commitment from a solar installer (not the panel manufacturer) that your system will produce...
Pure Sine Wave
Inverters & Charge Controllers
Pure sine wave refers to the quality of AC power output from an inverter. A pure sine wave inverter produces smooth, con...
PWM
Electrical Fundamentals
PWM stands for Pulse Width Modulation, a simpler and less expensive solar charge controller technology that regulates ch...
PWM Charge Controller
Inverters & Charge Controllers
A PWM charge controller is a basic solar charge regulation device that connects panels directly to batteries and control...
R
Racking
Installation
Racking is the mounting hardware that secures solar panels to a roof, ground structure, or pole. It includes the rails, ...
Rail Mount
Installation
Rail mount is the standard solar panel mounting method that uses continuous aluminum rails bolted to the roof structure ...
Rapid Shutdown
Installation
Rapid shutdown is a National Electrical Code (NEC) safety requirement that mandates solar systems reduce rooftop DC cond...
Roof Mount
Installation
Roof mount is the most common solar panel installation method, securing panels directly to the building's rooftop using ...
S
Self-Consumption
System Types
Self-consumption is the practice of using solar-generated electricity directly in your home at the time it is produced, ...
Series Wiring
Electrical Fundamentals
Series wiring connects solar panels end-to-end by linking the positive terminal of one panel to the negative terminal of...
Shade Analysis
Installation
Shade analysis is the process of evaluating how much sunlight a proposed solar installation site receives throughout the...
Shingled Cell
Panel Technology
Shingled cell panels use strips of solar cells that overlap like roof shingles, with each strip's edge layered beneath t...
Short-Circuit Current (Isc)
Electrical Fundamentals
Short-circuit current (Isc) is the maximum current a solar panel can produce when its positive and negative terminals ar...
Solar Irradiance
Installation
Solar irradiance is the power density of sunlight striking a surface, measured in watts per square meter (W/m²). It quan...
Solar Lease
Incentives & Policy
A solar lease is a financial arrangement where you pay a fixed monthly fee to a third-party company that installs, owns,...
Solar Panel Warranty
Financial
Solar panel warranties come in two distinct components: the product warranty covering manufacturing defects and physical...
Solar Pathfinder
Installation
A Solar Pathfinder is a site assessment tool used by solar installers to evaluate shading at a proposed panel location t...
Solar ROI
Financial
Solar ROI (return on investment) measures the total financial return of a solar system over its lifetime, expressed as a...
SREC
Incentives & Policy
A Solar Renewable Energy Certificate (SREC) is a tradeable certificate representing the environmental attributes of one ...
Standard Test Conditions (STC)
Electrical Fundamentals
Standard Test Conditions (STC) define the specific laboratory environment under which all solar panel ratings are measur...
State of Charge (SoC)
Battery Storage
State of charge (SoC) is the percentage of a battery's current energy level relative to its full capacity. A battery at ...
String
Electrical Fundamentals
A string is a group of solar panels connected in series to create a higher-voltage circuit. The term comes from the visu...
String Inverter
Inverters & Charge Controllers
A string inverter is a centralized device that converts the DC electricity produced by a series-connected string of sola...
String Sizing
Installation
String sizing is the process of calculating how many solar panels to wire in series per string to ensure the combined vo...
T
Temperature Coefficient
Panel Technology
Temperature coefficient measures how much a solar panel's power output decreases for every degree Celsius the cell tempe...
Thin-Film
Panel Technology
Thin-film solar panels are made by depositing one or more layers of photovoltaic material onto a substrate such as glass...
Tilt Angle
Installation
Tilt angle is the angle at which solar panels are inclined relative to the horizontal ground surface. It is one of the t...
Time-of-Use (TOU)
System Types
Time-of-use (TOU) is a utility rate structure that charges different electricity prices depending on the time of day, da...
TOPCon
Panel Technology
TOPCon stands for Tunnel Oxide Passivated Contact, a next-generation solar cell architecture that improves on PERC techn...
Transfer Switch
Inverters & Charge Controllers
A transfer switch is an electrical device that switches a home's electrical loads between two or more power sources — ty...
W
Watt-Hour (Wh)
Battery Storage
A watt-hour (Wh) is a unit of energy equal to one watt of power sustained for one hour. It is the most practical unit fo...
Watt-Peak (Wp)
Panel Technology
Watt-peak (Wp) is the standard unit for rating the maximum power output of a solar panel under Standard Test Conditions ...