Punjab PSEB Sr. Sec. NSQF Electronics (Solar Panel Installation Technician) key terms

The process by which a semiconductor material converts absorbed light energy directly into electrical current, releasing electrons that flow through an external circuit when the material is connected to a load.

The instantaneous power of sunlight falling on a surface, measured in watts per square metre. Standard test conditions use 1000 W/m², and module output current rises roughly in proportion to this value.

The daily solar energy received at a site expressed as the number of hours of full 1000 W/m² sunshine it is equivalent to; used to estimate daily energy yield from array capacity.

The laboratory reference conditions for module ratings: 1000 W/m² irradiance, 25 °C cell temperature and a specified air mass spectrum. Nameplate wattage is valid only at these conditions.

The percentage by which module power changes for each degree Celsius rise in cell temperature above 25 °C. Power normally falls as cells heat up, so hot-site output is below the nameplate figure.

The cell temperature a module reaches in a standard outdoor test at 800 W/m², 20 °C ambient air and 1 m/s wind. It indicates how much hotter than ambient a module runs.

A graph plotting module current against voltage over the full range from short circuit to open circuit. It shows short-circuit current, open-circuit voltage and the maximum power point where the product is greatest.

The single operating point on a module's I-V curve where current multiplied by voltage is highest. MPPT charge controllers and inverters continuously track this point to extract maximum available energy.

The ratio of a module's maximum power to the product of its open-circuit voltage and short-circuit current. A higher value indicates a squarer I-V curve and better cell quality.

The voltage measured across module terminals with no load connected and full light on the surface. It is the highest voltage the module produces and rises slightly as cell temperature falls.

The current that flows through a module when its terminals are joined by a near-zero-resistance path under illumination. It is roughly proportional to irradiance and is used to check module health.

The smallest generating unit of a photovoltaic system, usually a silicon wafer with a p-n junction that produces roughly 0.5 to 0.7 V under illumination. Cells are connected in series inside a module.

A sealed, framed assembly of series-connected solar cells laminated between glass and backsheet, with a junction box and cables. It is the unit sold, transported and mounted on site.

The complete electrical assembly of modules connected in series strings and parallel branches to deliver the required voltage and current to the inverter or charge controller.

A group of modules wired in series so their voltages add while the same current flows through each. String length must respect the inverter's maximum input voltage at the coldest expected temperature.

A diode inside the module junction box that provides an alternative path around a shaded or faulty cell group, limiting heating and power loss when part of the module is shaded.

A localised overheated area on a cell caused by mismatch, shading or a failed bypass diode, where the shaded cell dissipates power instead of generating it. It can crack glass or start a fire.

A gradual loss of module power caused by high voltage stress between the cells and the grounded frame, often worsened by moisture and heat. Proper earthing and module choice reduce the risk.

A module made from single-crystal silicon wafers, recognisable by uniform dark colour and cut corners. It offers the highest efficiency per unit area but usually costs more per watt.

A module made from multicrystalline silicon, showing a bluish, speckled surface. It is slightly less efficient than monocrystalline but often cheaper, and its output falls more in high heat.

A module formed by depositing very thin semiconductor layers such as cadmium telluride or copper indium gallium selenide on a substrate. It is flexible and cheap but needs more area per watt.

The share of incident solar power that a module converts into electrical power, calculated as maximum power divided by area times 1000 W/m². It determines the roof area needed.

The angle at which a module surface is raised above the horizontal. In Punjab a tilt near the local latitude, roughly 30 degrees, maximises annual yield and helps rain clean the glass.

The compass direction a module surface faces, measured in degrees from true north. In the northern hemisphere a true-south orientation, about 180 degrees, gives the highest annual energy.

The site assessment that identifies objects or structures casting shadows on the array during the day and year, using a solar path chart or shadow-measuring tool to size the clear area.

The systematic listing of every appliance to be powered, with its wattage and daily hours of use, to calculate total daily energy demand in watt-hours before sizing the array and battery.

The calculation of module capacity and count needed to meet daily energy demand, dividing load energy by peak sun hours and system losses, then allowing for temperature and dirt derating.

The percentage of a battery's capacity that has been withdrawn before recharging. Limiting discharge, typically to 50 percent for lead-acid, extends service life and must be included in sizing.

The remaining energy in a battery expressed as a percentage of its full capacity. Charge controllers and battery monitors use voltage or current counting to estimate it and prevent over-discharge.

A charge controller that continuously adjusts its input operating point to draw maximum power from the array while converting voltage to suit the battery, giving more yield than simpler controllers.

A charge controller that connects the array to the battery through rapid on-off switching, wasting any array voltage above battery voltage. It suits small systems where array and battery voltages match.

An inverter that synchronises its AC output with the utility supply, exporting surplus solar power to the grid and shutting down automatically when the grid fails, as required by anti-islanding protection.

An inverter that manages solar input, battery charging and discharge, and grid or generator supply in one unit, allowing backup power during outages and programmable priority of energy sources.

A protective function that stops a grid-tied inverter feeding power within milliseconds of grid failure, preventing electric shock to utility staff repairing lines during an outage.

A locking, polarised, touch-protected DC connector used to join module and string cables. Correct crimping with the matching tool and the same brand on both halves prevents heating and fire.

An enclosure where several parallel strings are joined onto common busbars, each string protected by a fuse, with a DC isolator and surge protection before a single cable runs to the inverter.

Bonding all exposed metalwork, module frames and inverter enclosures to a buried electrode so fault current trips protection devices and touch voltage stays safe for people.

A component that diverts brief high-voltage spikes from lightning or switching to earth, protecting modules, inverter and electronics. It is installed on DC and AC sides with short, direct earth connections.

A protective switch that trips when it detects current leaking to earth through a person or faulty insulation, cutting supply before injury. Solar AC circuits require it for shock protection.

A test using a high-voltage insulation tester to measure resistance between live conductors and earth, confirming cable and module insulation is sound before energising the system.

A handheld instrument measuring voltage, current, resistance and continuity. In solar work it checks array polarity, open-circuit voltage, fuse continuity and battery voltage before commissioning.

A meter whose jaws encircle a conductor and read current from its magnetic field without breaking the circuit. A DC-capable clamp meter measures string and battery current during testing.

The adjustment of module open-circuit voltage for the coldest expected site temperature, using the datasheet voltage coefficient, to confirm the string never exceeds inverter maximum input voltage.

A safety procedure in which the energy source is switched off, physically locked and tagged with the holder's name so equipment cannot be re-energised while someone works on it.

Wearable safety gear for solar work, including insulated gloves, safety helmet, safety harness for roof work, safety footwear, eye protection and high-visibility clothing as the task requires.

A harness and lanyard arrangement anchored to a certified point that stops a worker's fall from a roof or structure and limits the distance fallen. It is mandatory above height thresholds.

The relationship stating that voltage equals current multiplied by resistance in a circuit. Technicians use it to find expected current, voltage drop in cables and resistance of loads.

Electrical power in a DC circuit equals voltage multiplied by current, and energy equals power multiplied by time. These formulas underpin load assessment, sizing and customer quotations.

The loss of voltage along a cable caused by its resistance, proportional to current, length and conductor resistivity. Keeping it below about 3 percent avoids inverter faults and wasted energy.

Selecting conductor cross-sectional area so current-carrying capacity exceeds expected current while voltage drop and heating stay within limits, accounting for derating in conduit and high ambient temperature.

A diode placed in series with a string or array to prevent reverse current from a stronger string or battery flowing back through weaker modules at night or under mismatch.

A billing arrangement in which surplus solar energy exported to the grid is credited against units imported, so the consumer pays only for the net difference over the billing period.

A public programme offering capital subsidy or concessional finance for rooftop solar, with eligibility, capacity limits and application through a designated portal. Verify current terms before quoting.

A written offer to a customer listing system capacity, equipment makes, scope of work, warranty terms, taxes, subsidy adjustment and total price, with validity period and payment schedule.

The final site process of inspecting, testing and energising the installed system, recording voltages, currents and insulation readings, and handing over documentation and user training to the customer.

The ratio of actual energy generated over a period to the theoretical energy the array would produce at standard conditions, revealing losses from heat, dirt, shading and faults.