Accelerated Depreciation

Accounting methodology under which certain Fixed Assets can be depreciated at higher rates in the early years of their asset lives. This directly translates to tax savings.

Alternating Current (AC)

Current which changes its polarity, magnitude and direction in a cycle. (50 cycles per second in India)

Array (Solar Array)

Whole groups (strings) of modules in a solar PV system.


Tracking control mechanism (algorithm) which minimizes the panel-on-panel shading.

Bi-directional Energy meter (Net meters)

A meter which moves in both directions. It moves in forward direction when you import power from the grid and in backward direction when you export power into the grid.


One of the ownership models, wherein users have to pay the total cost of the system to system integrator and are also responsible for O&M.


In this model, the solar system is owned by Rooftop owner and has to bear the cost of solar syatem. Rooftop owner will also be responsible for operating & maintating the solar system.

Capacity Utilization factor (CUF)

Ratio of actual electrical energy generated over maximum possible energy for any given time frame.

Capital subsidy

Subsidy on solar system cost will be granted by MNRE subject to approval & availability of funds. You have to contact State Nodal Agency/ Energy Department for availing the same.

Central Financial Assistance (CFA)

Subsidy or support, which may be provided by MNRE (Ministry of New and Renewable Energy) for the installation of Solar PV Systems in residential, institutional, social sector or government buildings, if they qualify certain conditions.

Central Inverters

Used in large scale applications. Here strings are connected to a central box (combiner box), output of which is then connected to the inverter.

Connected Load

Sum of rated capacity of your electrical appliances/equipment.

Corrective Maintenance

Task performed to bring failed equipment to its working condition.


Delhi Electricity Regulatory Commission

Data Logger

The device which logs events (breakdowns, shut downs etc.) and different parameters of equipment for further monitoring and analysis.

Direct Current (DC)

Current which flows in only one direction without changing its polarity and magnitude.

Feed in tariff

Payment made to houses or businesses which generate their own electricity without hampering natural resources. The payment is proportional to the power generated.

Fixed tilt

Optimum panel tilt fixed for the whole year (generally equal to latitude of the site) to maximize the power output of the panel.

Grid Parity

The level at which levelised cost of electricity produced by the solar system is equivalent to the price of purchasing electricity directly from the grid/local utility.

Grid Synchronisation

Process of matching voltage and frequency of generator to the grid or electrical network. In solar it is done by solar Inverter.

Gross Metering

Metering mechanism to record the entire generated power fed to the grid. No power consumption is allowed at generation end.


A promise or assurance from an equipment manufacturer, which enables the customer to replace the complete item if it underperforms the prescribed standards within a specified period of time.

HT Line

Tension Line used for supply of 11kV and above.


Amount of solar energy received per unit area in unit time. It is measured in kWh/m2.


Contract by which an insurance company provides compensation in case of occurrence of a specified damage or loss.


The rate at which sunlight is received by a surface at a given point of time. It is typically expressed in W/m2 (watt per square metre).

LCOE (Levelised cost of energy)

LCOE from a power plant signifies how much each unit of generated electricity would cost if the total cost of setting up and operating the plant was spread over its lifetime. It’s the most commonly used metric for comparing the cost of electricity generated from different sources.

LT Line

Low Tension line having supply of 415V for 3-phase and 230V for single phase connection.


Angular distance of a location from the equator.

Local Distribution transformer capacity

Capacity of transformer installed at nearest electrical sub-station for supplying electricity to all houses in your area.


Angular distance of a location from Greenwich Meridian.


Ministry of New & Renewable Energy, Govt. of India

MPPT (Maximum Power Point Tracking)

A technique used to maximize power from solar PV system.

Micro inverters

Connected with each solar panel and converts DC power into AC at module level.

Net Metering

Billing mechanism which allows consumers to utilize the generated solar power for their own purpose and feed the generated power to the grid which they don’t use.

Nodal Agency

Administrative agency of state government having responsibility to support the implementation of solar policies and programs.


Operation and maintenance of solar PV system.

Off Grid Solar

A standalone system that is not connected to the grid. Its capacity typically ranges from 1 kW (individual home) to 100 kW and even more, and is supported with battery bank. Most commonly installed in rural areas, where access to grid is either poor or not available.

On Grid Solar

A system that is connected to the utility power source or your existing electrical network.


Power Conditioning Unit simply known as inverter.

PPA (Power Purchase Agreement)

An agreement between the seller of power and the purchaser. It includes term of the agreement, quantum of electricity, rate of power and other commercial terms.

Panel Degradation

Fall in the power output of solar panel with respect to manufacturer’s specification due to its exposure to the sunlight during its lifecycle.

Panel tilt

Angle at which solar panel is mounted on the structure.

Payback period

The time period required to recover the total cost of your investment.

Peak Load

Maximum load on any electrical network/system during any specified time frame like during day, month and year.

Performance Ratio (PR)

An actual performance indicator of solar power system, which shows how efficiently your solar system is performing.


Covers the conversion of solar energy into direct current electricity using semiconducting materials, such as silicon, Gallium, CdTe etc.

Power Quality

Ensures a stable power whose voltage and frequency varies within of specified tolerance.

Preventive Maintenance

Planned maintenance to reduce or eliminate the possible breakdown or failure of any equipment.

Priority sector lending

Banks give solar sector a priority (i.e. first preference) in obtaining loans from banks at a low rate of interest. Renewable energy sector has been added to priority sector lending in the year 2015.


One of the ownership models, wherein user is not required to pay the total cost of the system upfront to system integrator. Here users have to pay only cost of energy on per unit basis as per agreed terms with solar system integrator.


In this model, the solar system is not owned by Rooftop owner. 3rd party owner will operate and maintain the system. No upfront cost is to be paid by rooftop owner and he has to pay only for the energy generated from the solar system on agreed rate for specifed time period.

Recurring costs

The costs that are incurred repeatedly during the entire lifecycle of project. For instance, Operations and maintenance costs.

Return on Investment (ROI)

A performance indicator of your Investment. High ROI number means high profitability.

Roof angle

Slope angle of roof. Its value is zero for flat roof.

Roof orientation

Direction of roof with respect to its optimum position i.e. true south.

Sanctioned Load

Indicates maximum load that any consumer can utilize. Exceeding this may cause penalties from Distribution Company.

Seasonal tilt

Optimum panel tilt as per season (summer and winter) to maximize the power output.

Single phase power

Two wire supply system having one wire for power and other one is neutral. In India, 230V is standard single phase voltage.

Solar Hybrid system

A system that combines the solar power system with other power generating sources like DG, wind, biomass, gas or utility grid supply.

String (Solar String)

Grouping of solar panels (modules) wired together in series or parallel.

String Inverters

Strings wired directly to inverter to convert DC output of the string to AC power. It is generally used for small and medium scale applications.

Tandem Junction

Tandem junction is process to enhance the performance of thin film module.

Three phase power

Has 3 wires for power (R, Y, B) supply and one neutral wire. Standard voltage between phase to phase is 415V and between phase to neutral is 230V.

Tracking System

Orients the panel towards sun as per sun’s direction in order to maximize the power output from the solar panels.


The commercial organization that owns and operates the infrastructure required for the generation, transmission and/or distribution of electricity to the public.

Utility Scale Solar

Systems (generally in the form of solar farms) that are greater than 1 MW and connected to the medium/high voltage power grid.


A promise or assurance from an equipment manufacturer, which enables the customer to get the item repaired if any defects occur within a specified period of time.

kVA or Kilovolt-amp

Apparent power including active and reactive component of power together.

kWh or kilowatt-hour

The unit of electrical energy that is equivalent to the usage of 1000 watts for a period of one hour. The total amount of energy generated by your solar system is measured in kWh.

kWp or kilowatt-peak (Peak Power)

Commonly used measure of the maximum possible output of the solar system under standardised testing conditions (STC) i.e. irradiation 1000W/m2 at a temperature of 25 degree C and air mass 1.5.

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