Solar Glossary 2025 - Photovoltaics & PV terms explained simply

A · B · C · D · E · F · G · H · I · J · K · L · M · N · O · P · Q · R · S · T · U · V · W · Z

A

AC connection
The interface at which the inverter feeds the generated alternating current into the house grid.
Payback period
Period until the investment in a PV system pays off through saved electricity costs.
Connected load
Maximum power that may be connected to the house network or the mains connection.
Plant monitoring
Systems for recording yield, errors and operating data of the PV system.
Degree of self-sufficiency
Percentage of the home's electricity needs covered by the PV system.

B

Balcony power plant
Small plug-and-play PV system for balcony or terrace (usually 300–800 W).
Battery storage
Stores excess solar power for later use and increases self-consumption.
Bifacial module
Modules that absorb light from the front and back and can thus deliver higher yield.
Reactive power
Power that circulates in the grid but is not converted into usable active power.
BYD storage
Branded batteries with high scalability and reliability (LiFePO4 technology).

C

Charge Controller
Controller for controlling the charging of batteries in off-grid systems.
CIS solar module
Thin-film module type with good performance in diffuse light conditions.
CO2 balance
Ecological balance of a PV system over its life cycle.
Cradle to Cradle
Concept for recycling-friendly design and sustainable production.

D

roof hook
Mechanical fasteners for mounting PV rails on tiled roofs.
DC cable
Cables that carry direct current between solar modules and inverters.
Degradation
Long-term performance loss of solar modules due to aging.
Direct consumption
Electricity that is consumed directly in the household, without intermediate storage.
Double-glass module
Robust modules with glass on the front and back for longer service life.

E

Own consumption
Percentage of solar power generated that is used directly in the household.
Feed-in tariff
Compensation for solar power fed into the public grid.
Enphase microinverters
Microinverters that are installed per module and enable module optimization.
Energy management
Software and hardware solutions to optimize generation, consumption and storage.
Earnings forecast
Estimation of the expected energy yield of a PV system at a location.

F

Flat roof system
Mounting systems for modules on flat roofs (ballasted or screwed).
Funding programs
Regional and national subsidies for PV, storage and charging infrastructure.
Fronius inverters
Inverter manufacturer with extensive monitoring ecosystem.
Frequency converter
Technique for adjusting frequency and power in specific systems.
Full-black module
Aesthetically continuous black modules, popular for visible installations.

G

Glass-foil module
Standard construction: glass in front, polymer film in the back – lighter than glass-to-glass.
Glass-glass module
Extremely durable modules with two glass layers – low degradation.
GSE in-roof system
In-roof solutions that visually combine roof and PV module.
Warranty conditions
Manufacturer information on performance guarantees and product guarantees.
Generator connection box
Central connection point for strings, fuses and surge protection.

H

Half-cell module
Modules with split solar cells to reduce power losses due to shading.
Hybrid inverter
Combines inverter functions with battery storage management.
High-voltage storage
Storage systems with a high system voltage spectrum for greater power densities.
Hot spot effect
Local overheating of cells due to partial shading or defects.
High-efficiency module
Modules with particularly high efficiency – ideal for small roof areas.

I

IBC solar modules
High-performance modules with improved cell connections and high efficiency.
Island system
Self-sufficient PV system without grid connection, often with battery storage.
Installation accessories
Mounting materials, cables, plugs and small parts for installation.
IP protection class
Protection class against dust and water – relevant for outdoor components.
Commissioning protocol
Documentation of the safe commissioning and testing of the PV system.

J

Jinko solar modules
Brand for cost-effective, reliable solar modules.
Annual performance factor (APF)
Key figure for evaluating the efficiency of heating and energy systems over one year.

K

Kilowatt peak (kWp)
Nominal power of a module or system under standard test conditions.
Cable management
Neat and safe cable routing to prevent damage and loss.
KfW funding
KfW Bank funding programs for energy projects and storage.
Small wind power
Small wind turbines as a complement to PV at suitable locations.
Climate neutrality
The aim is to offset or avoid greenhouse gases through life cycle measures.

L

LiFePO4 battery
Safe, long-lasting lithium iron phosphate storage for PV applications.
Load management
Control of electrical consumers to optimize self-consumption.
charge controller
Regulates charging processes in off-grid systems and protects batteries from overcharging.
LG Solar
Well-known manufacturer of high-quality solar modules (brand example).
Performance optimizer
Module-specific optimizers that optimize modules independently of each other.

M

Monocrystalline
Highly effective cell technology with dark color and high efficiency.
Microinverters
Inverter per module for better shading performance.
Mounting rail
Aluminum or steel profile for mounting PV modules.
MPP tracker
Controls the optimal operating point of the modules for maximum yield.
Monitoring system
Software for monitoring plant performance and troubleshooting.

N

Grid feed-in
Excess solar power is fed into the public grid.
Emergency power function
Ability to provide local power to critical consumers in the event of a grid failure.
Zero feed-in
Technology to avoid grid feed-in (e.g. in case of regulatory requirements).
Tracking system
Mechanical systems that track modules to the sun and increase yield.
Rated power
The continuous power rating of a device or module.

O

Off-grid system
Self-sufficient system without grid connection, usually with storage and generator.
Open-loop system
Technical term for certain control architectures (example).
East-west orientation
Distribution of modules to the east and west for longer yield periods.
OptiTrac Global Peak
Example name for manufacturer algorithms for MPP optimization.

P

Photovoltaics
Direct conversion of sunlight into electrical current using solar cells.
PV storage
Storage specifically for the temporary storage of PV power.
Complete PV system
Pre-configured packages consisting of modules, inverters, mounting and accessories.
Peak power
Maximum power output under optimal conditions (kWp).
Plug-and-play system
Simple systems for self-installation without complex commissioning.

Q

Q-Cells
Brand example for solar modules with good price-performance ratio.
Quality control
Tests and inspections to ensure long life and performance.
Square module
Rare form factors; usually special design applications.

R

terminal block
Electrical terminal connectors for secure module or string connections.
Non-return valve
Prevents current from flowing back into certain branches of the system.
recycling
Recycling of module materials at the end of their life cycle.
Relay card
Electronic component for control and switching functions in systems.
Redox flow battery
Flow batteries with high scalability for stationary energy storage.

S

Smart Meter
Smart electricity meter for measuring consumption and feed-in.
Solar thermal energy
Generation of heat from solar energy (separate from PV).
SolarEdge inverters
Manufacturer known for module optimizers and monitoring solutions.
Storage capacity
Amount of energy that a storage device can store (kWh).
String inverter
Classic inverters for string configurations on roofs.

T

Trina solar modules
Well-known module manufacturer with a broad portfolio.
Trapezoidal sheet metal assembly
Mounting systems specifically for trapezoidal metal roofs.
Temperature sensor
Sensors for monitoring module temperature and performance.
Type 2 plug
Standard plug connection for AC charging of electric cars in Europe.
Tracking system
Mechanical tracking systems for maximum irradiation yields.

U

Surge protection
Protective devices that protect sensitive components from voltage spikes.
Conversion efficiency
Relationship between the input and usable power of a component.
Substructure
Supporting structure that holds modules securely on roofs or surfaces.
UPS system
Uninterruptible power supply for critical loads.

V

Remuneration rate
Fixed price for electricity fed into the grid (kWh) in certain programs.
Shading
Shading of modules by objects, which reduces performance.
Full load hours
Fictitious hours during which a system would operate at rated power to achieve the annual yield.
VDE standard
Technical standards and testing requirements for electrical systems in Germany.
V2G (Vehicle-to-Grid)
Technology for feeding energy from electric vehicles back into the grid.

W

Wallbox
Wall charging station for charging electric vehicles, often with smart functions.
Inverter
Converts direct current from the modules into grid-compliant alternating current.
Efficiency
Measure of the efficiency of components in energy conversion.
heat pump
Heating/cooling technology, easily combined with PV and storage.
Watt hours (Wh)
Unit for measuring energy (power over time).

Z

Bidirectional meter
Measures both the consumption and feed-in of electrical power.
Meter location
Location of the house installation where meters and connections are mounted.
Brick assembly
Mounting system for roof tiles with special roof hooks and fastenings.
Cycle stability
Information on the durability of batteries in charge/discharge cycles.