Solar Works Pakistan

Guides · Faisalabad, Lahore, Punjab

Solar Glossary: 50 Terms Explained in Plain English

Short answer

This solar glossary explains the 50 terms you are most likely to meet in a solar quotation, an inverter manual or your electricity bill in Pakistan, each in a sentence or two. Every term links to the Solar Works Pakistan guide that explains it in full, so you can go from "what does this mean?" to "what does it mean for my home or factory?" in one click.

Terms are grouped by topic: energy and sizing, panels, inverters, batteries, protection and installation, and bills, rules and the grid. Many buyers say "solar plate" for a solar panel; both mean the same thing here.

Energy, power and sizing

1. kW (kilowatt)

A measure of power: how fast electricity is being made or used at a given moment. Inverter size and solar array size are given in kW. See kW vs kWh explained.

2. kWh (kilowatt-hour), or "unit"

A measure of energy: power used over time. One kWh is one "unit" on your electricity bill, and battery capacity is given in kWh. See kW vs kWh explained.

3. kWp (kilowatt peak)

The rated power of a set of solar panels under standard test conditions. A "10 kW system" usually means about 10 kWp of panels. Real output is usually lower than kWp because of heat, dust and losses. See how many units a solar system produces in Punjab.

4. Specific yield (units per kW)

How many units each kW of panels produces in a year. It lets you compare sites and estimate production. See solar units per kW in Punjab.

5. Peak sun hours

The number of hours per day of full-strength sunlight that would deliver the day's total solar energy. It is a planning shortcut, not the hours of daylight. See solar units per kW in Punjab.

6. Price per watt

The price of a panel or system divided by its rated watts. It makes it easier to compare different panel sizes, but a full system costs more per watt than panels alone. See solar panel price per watt.

7. DC/AC ratio

Panel capacity (DC) divided by inverter output rating (AC). A modest ratio above 1 is normal practice, within the inverter's datasheet limits. See inverter DC/AC ratio.

8. Clipping

When panels can produce more than the inverter's maximum output, the inverter caps it and the extra is lost. A little clipping is normal with a sensible DC/AC ratio. See inverter DC/AC ratio.

9. Self-consumption (self-use)

The share of your solar output that you use on site rather than export. Under net billing, self-used units are worth much more than exported ones. See sizing your system under net billing.

Diagram

Three groups of solar terms

Power

W, kW, kWp

Energy

kWh = one unit on your bill

Grid

Net billing, import, export

Know these and most quotes become easy to read.

Solar panels

10. Monocrystalline, N-type and P-type

Today's panels use single-crystal (mono) silicon cells. N-type and P-type describe how the silicon is treated; most new panels are N-type, which generally ages more slowly and handles heat better. See N-type vs P-type and bifacial panels.

11. TOPCon, HJT and back-contact

Three N-type cell designs. TOPCon is widely sold in Pakistan; HJT (heterojunction) and back-contact designs are alternatives with their own strengths. See N-type vs P-type and bifacial panels.

12. Bifacial panel

A panel that also collects light reflected onto its back side. It gains most on elevated structures over light-coloured surfaces. See N-type vs P-type and bifacial panels.

13. Temperature coefficient

How much output a panel loses for each °C its cells rise above 25°C. Closer to zero is better in a Punjab summer. See solar panels in summer heat.

14. Degradation

The slow loss of panel output over the years. The datasheet and manufacturer's warranty state how much is expected. See solar panel lifespan.

15. Bypass diode

A small component inside a panel's junction box that lets current skip a shaded section, limiting the loss from partial shade. See how shading cuts solar output.

16. String

A group of panels wired in series so their voltages add up before they reach the inverter. String design must stay within the inverter's voltage and current limits. See series vs parallel wiring.

17. Voc (open-circuit voltage)

The voltage a panel produces with nothing connected. It rises in cold weather, so string length is checked against the coldest mornings. See series vs parallel wiring.

18. Tilt and azimuth

Tilt is the angle of the panels from flat; azimuth is the direction they face. In Punjab, south-facing at a tilt near the local latitude is the usual starting point. See solar panel angle and direction for Punjab.

19. Soiling

Dust, smog grime and bird droppings on the panel glass, which block light. Regular cleaning recovers most of the loss. See solar panels in fog and smog.

20. Genuine panel verification

Checking a panel's serial number with the manufacturer's official route to make sure it is not counterfeit. See how to check genuine solar panels.

Inverters and system types

21. Inverter

The device that turns DC power from panels and batteries into the AC power your home uses. It is the "brain" of the system. See hybrid vs on-grid vs off-grid.

22. On-grid (grid-tied) system

Panels and an inverter connected to the grid with no battery. It is the simplest setup, but it switches off during load-shedding. See can a solar inverter work without a battery?.

23. Hybrid system

Panels, a hybrid inverter and a battery, connected to the grid. It can use solar, battery and grid together and gives backup in outages. See hybrid vs on-grid vs off-grid.

24. Off-grid system

A system with no grid connection, running on panels and batteries alone. It suits sites without a reliable supply. See off-grid solar inverters.

25. MPPT (maximum power point tracking)

A circuit that keeps panels working at the voltage where they give the most power. Most modern inverters have MPPT built in. See MPPT vs PWM charge controllers.

26. Anti-islanding

A safety feature that shuts a grid-connected inverter down when the grid fails, so it does not energise lines that workers believe are dead. See can a solar inverter work without a battery?.

27. SBU and SUB modes

Output-priority settings on hybrid inverters. SBU uses solar, then battery, then utility; SUB uses solar, then utility, keeping the battery for outages. See SBU, SUB and utility-first modes.

28. Parallel inverters

Two or more matching inverters linked to share a load, for bigger homes or for three-phase supply. See running two inverters in parallel.

29. Single-phase and three-phase

Two types of supply. Most smaller homes are single-phase; larger homes, shops and factories are often three-phase, and net billing applies to three-phase connections. See three-phase vs single-phase inverters.

30. Optimiser and micro-inverter

Panel-level electronics that reduce the effect of shade or mismatched panels. Most homes in Pakistan do not need them. See optimisers and micro-inverters.

31. Monitoring (Wi-Fi dongle)

A small module that sends inverter data to a phone app, so you can see production, use and faults. See solar monitoring apps.

32. VFD (variable frequency drive)

A drive that runs a pump motor at varying speed, letting a tubewell run directly from solar panels. See solar tubewell with VFD.

Batteries and storage

33. LiFePO4 (lithium iron phosphate)

The lithium chemistry used in most solar batteries. It is valued for safety and long cycle life. See LiFePO4 vs tubular battery.

34. DoD (depth of discharge)

How much of a battery's capacity is used before recharging. Lithium batteries allow a deeper discharge than lead-acid, but a reserve is still kept. See LiFePO4 vs tubular battery.

35. C-rate

How fast a battery can charge or discharge compared with its capacity. 0.5C means a full discharge in about two hours. See kW vs kWh and C-rate.

36. BMS (battery management system)

The electronics inside a lithium battery that protect it from over-charge, over-discharge, overheating and imbalance, and talk to the inverter. See battery BMS explained.

37. Round-trip efficiency

The share of energy you get back from a battery compared with what you put in. Some energy is always lost in charging and discharging. See should you charge your battery from the grid?.

38. High-voltage vs low-voltage battery

Low-voltage batteries are usually 48 V units; high-voltage batteries stack modules to several hundred volts. The inverter decides which type you can use. See high-voltage vs low-voltage batteries.

39. BESS (battery energy storage system)

A larger battery system, usually for commercial or industrial sites, used for backup, self-use and cutting demand peaks. See BESS for factories.

40. Peak shaving

Using a battery to supply power during short spikes in demand, so the grid sees a lower peak. It matters where bills include demand (MDI) charges. See BESS for factories.

Protection, structure and installation

41. MC4 connector

The standard plug-and-socket connector used on solar panel cables. Poorly crimped or mismatched connectors are a common cause of faults. See MC4 connectors and earthing.

42. SPD (surge protection device)

A device that diverts voltage spikes from lightning or switching safely to earth, protecting the inverter. See earthing and surge protection.

43. Earthing

A low-resistance path from the system's metal parts and protection devices to the ground. It is essential for safety and for SPDs to work. See earthing and surge protection.

44. MCB, MCCB and RCCB

Three types of breaker. MCBs protect smaller circuits, MCCBs handle larger currents, and RCCBs trip on earth leakage to protect people. See MCB vs MCCB vs RCCB.

45. Changeover switch

A switch that moves your load between sources, such as grid, generator and solar, without connecting them together. See changeover switch for solar.

46. Zero export (export limiting)

A sensor and inverter setting that stops solar power flowing out to the grid, used when you have no net billing agreement or an export limit. See zero export device.

47. Elevated structure

A mounting frame that raises panels well above the roof or ground, keeping the roof usable and clearing shade from water tanks. See L2 vs L3 vs elevated structures.

Bills, rules and the grid

48. Net billing

Pakistan's arrangement for new solar connections since 9 February 2026. Units you import are billed at your tariff; units you export are credited separately at a lower rate linked to the national average energy purchase price. See net metering and net billing in Pakistan. The older terms net metering and gross metering are compared in net metering vs gross metering vs net billing.

49. Sanctioned load

The load in kW your electricity connection is approved for, printed on your bill. Under net billing, your solar capacity cannot exceed it. See how to read your electricity bill.

50. MDI (maximum demand indicator)

The highest demand in kW recorded on a commercial or industrial meter during the month. Where the tariff includes fixed charges per kW, MDI affects them. See MDI in your electricity bill.

A few more you will hear

Get today's price or a free site survey

If a term in your quotation is still unclear, ask us. Our engineers will explain it plainly and show you how it affects your system.

Site surveys are normally free. Solar Works Pakistan was founded in 2021 and has served 300+ customers, including 50+ industrial clients.

Frequently asked questions

What is the difference between kW and kWh?

kW is power, how fast electricity flows at a moment. kWh is energy, power over time, and one kWh is one unit on your bill. Inverters are sized in kW; batteries store kWh.

What does a "unit" of electricity mean?

One unit is one kilowatt-hour (kWh). Running a 1,000 W appliance for one hour uses one unit. Your bill counts the units you take from the grid each month.

What is MPPT in a solar inverter?

MPPT is a circuit that keeps the panels working at the voltage that gives the most power as sunlight and temperature change. Almost all modern hybrid and on-grid inverters have one or more MPPT inputs built in.

What is DoD in a battery?

Depth of discharge is how much of the battery's capacity you use before recharging. Lithium (LiFePO4) batteries allow deeper discharge than lead-acid, but designers still keep a reserve to protect battery life.

What is net billing in simple words?

You pay your normal tariff for every unit you take from the grid, and you get a lower credit for every unit you export. It replaced net metering for new solar connections in Pakistan from 9 February 2026.

What is sanctioned load and why does it matter for solar?

It is the kW your connection is approved for, shown on your bill. Under net billing, your solar system cannot be larger than your sanctioned load, so you may need to raise it first.

Is a solar plate the same as a solar panel?

Yes. "Solar plate" is a common name in Pakistan for a solar panel or module. The terms in this glossary apply to both.