Solar Power Glossary: 50 Terms Every Beginner Should Know
A beginner-friendly guide explaining 50 important solar energy terms, from PV and inverters to batteries, MPPT, BMS, and system design concepts.
Guide · July 21, 2026 · 12 min read
Solar energy involves many electrical and technical terms that can be confusing for beginners.
When planning a solar power system, you may encounter terms such as PV, MPPT, Voc, Vmp, BMS, SoC, inverter efficiency, and net metering. Understanding these terms makes it easier to choose equipment, compare products, and design a reliable PV system.
This glossary explains 50 common solar energy terms in simple language.
1. Photovoltaic (PV)
Photovoltaic refers to the process of converting sunlight directly into electricity.
Solar panels are also called PV panels because they use photovoltaic cells to generate electrical power.
2. Solar Cell
A solar cell is the smallest unit inside a solar panel that converts sunlight into electricity.
Most modern solar cells are made from silicon.
Multiple solar cells are connected together to create a solar panel.
3. Solar Panel
A solar panel is a collection of connected solar cells designed to generate electrical energy from sunlight.
A typical residential panel may produce between 300W and 600W.
4. Solar Array
A solar array is a group of multiple solar panels connected together.
Example:
- One panel = solar panel
- Ten connected panels = solar array
5. DC (Direct Current)
DC electricity flows in one direction.
Solar panels and batteries naturally produce DC electricity.
Example:
Solar Panel → Battery = DC power
6. AC (Alternating Current)
AC electricity changes direction periodically.
Homes and businesses typically use AC electricity for appliances.
Example:
Inverter output → Home appliances
7. Voltage (V)
Voltage is the electrical pressure that pushes current through a circuit.
Higher voltage allows electricity to travel more efficiently over long distances.
8. Current (A)
Current, measured in amperes (amps), is the flow of electrical charge.
More current means more electricity is moving through the circuit.
9. Watt (W)
A watt is a unit of electrical power.
The relationship between voltage, current, and power is:
Power = Voltage × Current
Example:
12V × 10A = 120W
10. Kilowatt (kW)
A kilowatt equals 1,000 watts.
Example:
A 5 kW PV system can produce up to 5,000 watts under ideal conditions.
11. Kilowatt-Hour (kWh)
A kilowatt-hour measures energy usage or production over time.
Example:
A 1kW appliance running for 5 hours uses:
5kWh
Electricity bills are usually measured in kWh.
12. Energy Yield
Energy yield refers to how much electricity a PV system produces over a specific period.
Example:
A PV system produces:
- 20kWh per day
- 600kWh per month
13. Inverter
An inverter converts DC electricity from solar panels or batteries into AC electricity used by appliances.
Types include:
- Grid-tied inverter
- Off-grid inverter
- Hybrid inverter
14. Hybrid Inverter
A hybrid inverter combines multiple functions:
- Solar conversion
- Battery charging
- Grid interaction
- Backup power
It is commonly used in modern home PV systems.
15. Grid-Tied System
A grid-tied PV system connects directly to the electrical utility grid.
Excess solar energy can often be exported back to the grid through net metering.
16. Off-Grid System
An off-grid system operates independently without utility power.
It usually requires:
- Solar panels
- Batteries
- Charge controller
- Inverter
17. Battery Storage
A battery stores excess solar energy for later use.
Energy stored during the day can be used at night or during power outages.
18. Battery Capacity (Ah)
Amp-hour (Ah) measures battery capacity.
Example:
A 100Ah battery can theoretically provide:
100 amps for 1 hour
or
10 amps for 10 hours.
19. State of Charge (SoC)
SoC represents the current battery charge level.
Example:
- 100% SoC = Full battery
- 50% SoC = Half charged
- 20% SoC = Low battery
20. Depth of Discharge (DoD)
Depth of Discharge describes how much battery capacity has been used.
Example:
A battery discharged from 100% to 30% has a:
70% DoD
21. Battery Management System (BMS)
A BMS protects lithium batteries by monitoring:
- Voltage
- Current
- Temperature
- Cell balance
It prevents overcharging and deep discharge.
22. Charge Controller
A charge controller regulates power from solar panels to batteries.
It prevents:
- Overcharging
- Excess current
- Battery damage
23. PWM Controller
PWM (Pulse Width Modulation) is a basic type of solar charge controller.
Advantages:
- Low cost
- Simple design
Disadvantage:
- Lower efficiency compared with MPPT
24. MPPT Controller
MPPT stands for:
Maximum Power Point Tracking
An MPPT controller adjusts the operating point of solar panels to extract maximum available power.
25. Maximum Power Point (MPP)
The MPP is the operating point where a solar panel produces its highest possible power.
It changes depending on:
- Sunlight
- Temperature
- Load conditions
26. Voc (Open Circuit Voltage)
Voc is the maximum voltage a solar panel produces when no load is connected.
It is important when designing panel strings.
27. Vmp (Voltage at Maximum Power)
Vmp is the voltage where a solar panel produces its rated power.
28. Isc (Short Circuit Current)
Isc is the maximum current produced when the positive and negative terminals are directly connected.
29. Imp (Current at Maximum Power)
Imp is the current produced when the panel operates at its maximum power point.
30. Efficiency
Solar panel efficiency measures how much sunlight is converted into electricity.
Higher efficiency means more power from the same panel area.
31. Solar Irradiance
Solar irradiance measures the amount of solar energy reaching a surface.
It affects how much electricity panels produce.
32. Peak Sun Hours
Peak sun hours represent the equivalent hours of strong sunlight received each day.
Example:
5 peak sun hours means:
5 hours of sunlight at maximum intensity.
33. Temperature Coefficient
The temperature coefficient shows how solar panel performance changes with temperature.
Most panels lose efficiency as temperature increases.
34. Degradation Rate
Solar panels slowly lose performance over time.
A typical panel may degrade around 0.3–0.5% per year.
35. Microinverter
A microinverter is a small inverter installed on each solar panel.
Advantages:
- Better monitoring
- Improved shading performance
36. String Inverter
A string inverter connects multiple solar panels together into one group or "string."
It is commonly used in residential systems.
37. Solar String
A solar string is a group of panels connected in series.
Series connections increase voltage.
38. Series Connection
Connecting panels in series increases voltage while keeping current the same.
Example:
20V + 20V = 40V
39. Parallel Connection
Connecting panels in parallel increases current while keeping voltage the same.
Example:
10A + 10A = 20A
40. Bypass Diode
A bypass diode helps reduce power loss caused by shading or damaged solar cells.
41. Net Metering
Net metering allows solar owners to send excess electricity back to the grid and receive credits.
42. Solar Monitoring
Solar monitoring systems track:
- Energy production
- Battery status
- System performance
- Fault warnings
43. Inverter Efficiency
Inverter efficiency shows how much DC energy is converted into usable AC energy.
Example:
95% efficiency means 5% energy is lost during conversion.
44. Surge Power
Surge power is the temporary high power required when starting certain appliances.
Examples:
- Refrigerators
- Pumps
- Air conditioners
45. Load
A load is any device that consumes electricity.
Examples:
- Lights
- Fans
- Refrigerators
- Computers
46. Backup Power
Backup power allows a suitably configured PV and battery system to continue supplying electricity during grid outages.
Usually requires batteries and a suitable inverter.
47. Battery Cycle
One battery cycle represents one complete charge and discharge process.
Battery lifespan is often measured in cycles.
48. Lithium Iron Phosphate (LiFePO4)
LiFePO4 is a popular lithium battery chemistry used in solar storage systems.
Advantages:
- Long lifespan
- High safety
- Good thermal stability
49. Building Integrated Photovoltaics (BIPV)
BIPV means integrating solar technology directly into building materials.
Examples:
- Solar windows
- Solar roof tiles
- Solar walls
50. Solar Simulator
A solar power simulator is a tool that allows users to design and test PV systems digitally.
It can simulate:
- Solar panels
- Batteries
- Inverters
- Loads
- Energy flow
Solar simulators help users understand system performance before building a real installation.
Use the Terms to Trace One Circuit
The terms become useful when they answer different questions in the same circuit. Voc and Isc describe boundary conditions for the PV source; Vmp and Imp describe its maximum-power operating point; watts describe the present rate of energy transfer; and watt-hours accumulate that transfer over time.
When a specification is unclear, identify whether it describes an input, an operating value, a safety limit, or accumulated energy. That simple classification prevents mistakes such as comparing batteries by amp-hours at different voltages or treating module Voc as normal operating voltage.
Use the glossary on a live PVAlign circuit
Build one panel, controller, battery, inverter, and load path. Locate Voc, Vmp, Isc, Imp, SoC, DC, AC, watts, VA, power factor, voltage drop, and efficiency in the node labels or inspectors. Change a single rating and trace which terms describe an input, an operating value, a limit, or an accumulated energy result.
Reference sources
Test the variables in PVAlign
Open a reference circuit, then change one input at a time—such as irradiance, temperature, component rating, wiring, or load—and compare the simulated voltage, current, power, losses, and operating state.