Help Center Materials

Definitions of Panel Specifications

Published on 22 Sept 2023

The following guide provides definitions of the various panel specifications on the Materials page.


Basic Details

Default inverter: Optional selection to designate a standard inverter model to use when the current panel model is added to a design. A different inverter may still be selected within a project.

Applicable states: For companies operating in multiple U.S. states or territories. Determines whether the panel can be added to projects based anywhere or only those in the selected locations.

Manufacturer: The name of the company producing the panel.

Model: The name or identifying number for the panel within the manufacturer's product line.

Product image: An image of the panel which appears on the webquote under the Materials section.

Product YouTube URL: Optional link to a YouTube video with product information for the panel.

Spec sheet: A PDF of the manufacturer's spec sheet for the panel model.

Spec sheet pages: Used to specify which pages should be included in permit plan sets featuring the panel.

Selling price per unit: For BOM-based pricing.

Additional document: Optional supporting materials related to the module.

Warranty: Duration in years of the warranty period for the panel.

Electrical Details

Maximum power rating (Pmax) – STC (W): This is the maximum power rating measured under standard test conditions (STC) of a cell temperature of 25 °C, and irradiance of 1,000 W/m² and an air mass of 1.5.

Maximum power rating (Pmax) – PTC (W): This is the maximum power rating measured under PVUSA test conditions (PTC), defined as an ambient temperature of 20 °C, irradiance of 1,000 W/m², and wind speed of 1 m/s at 10 m above ground level.

Isc – Short circuit current (A): This is the short circuit current which will result if electrical parts connect and protection has not yet intervened, measured per STC.

Voc – Open circuit voltage (V): This is the difference in electrical potential between two terminals of the electrical cables, measured per STC.

Imp – Maximum power current (A): This is the maximum current that may result during operation, measured per STC.

Vmp – Maximum power voltage (V): This is the maximum voltage that may result during operation, measured per STC.

TIsc – Current temperature coefficient (%/°C or A/°C): The rate of change in current output per 1 °C change in temperature.

TVoc – Voltage temperature coefficient (%/°C or V/°C): The rate of change in voltage output per 1 °C change in temperature.

TPmax – Power temperature coefficient (%/°C or W/°C): The rate of change in power output per 1 °C change in temperature.

Nominal operating cell temperature (°C): The temperature reached by open-circuited cells when exposed to an irradiance of 800 W/m², air temperature of 20 °C, and wind velocity of 1 m/s.

Panel efficiency: The percentage of solar energy reaching the panel which it can convert and output as electric energy.

Energy degradation: Anticipated year over year production loss as the panel ages.

Physical Details

Panel type: Either monocrystalline, polycrystalline, thin film, bifacial, heterojunction technology (HJT), or passivated emitter and rear cell (PERC).

Cell count: Quantity of solar cells housed on the panel.

No. of submodules: Quantity of submodules featured by the panel. Submodule are groups of solar cells which are wired together and protected by a bypass diode, so that if one part the panel is shaded or faulty, the rest remains viable.

Submodule partition:The means by which cells inside a panel are grouped into submodules.

Length (in or mm): The length of the long side of the panel.

Width (in or mm): The lengh of the short side of the panel.

Thickness (in or mm): The length of the distance from front to back on the panel.

Weight (lb or kg): The total weight of the panel.

Black on black panel: Indicates a black-on-black panel.

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