It is essential for you to enter an appropriate value for the System Efficiency, and to understand what this number should and should not include. It is not calculated by Nearmap.

System Efficiency should take into account, if possible:

  • Inverter AC-to-DC conversion efficiency, if applicable
  • Battery conversion efficiency, if applicable
  • Loss from shading, if structures, hills, or other panels will block available light some of the time
  • Wiring losses
  • Dirt or dust on the panels
  • Lost power due to outages for grid-tie systems or maintenance periods
  • Manufacturer tolerances
  • Any voltage mismatch among system components

System Efficiency should not account for:

  • The panel temperature
  • The sunlight available at the location

Panel Parameters

The panel parameters can be found in the Panels tab of the Solar tool.

Manufacturer and Model

All the panels on this list should be CEC-approved, but please verify at the CEC accreditation website as approved panels change over time. There are many CEC-approved panels that have not been added to our database yet. If your model of interest is not listed, select a similar one by the manufacturer, or just select Custom, and modify the panel parameters as you wish.


Nominal power at standard test conditions. This is what the panels are capable of producing under 1000 W/m² irradiance at 25 C. It will almost always considerably exceed real-world performance.


Nominal Operating Cell Temperature. This is the temperature that the manufacturer expects the panels to heat up to during operation in nominal operating conditions, which are 800 W/m² irradiance, 20 C, a 45 degree tilt angle, and 1 m/s wind. It is typically between 45-48 C.

Temperature Coefficient of Power

This corresponds to the percentage of power lost for each degree above 25 C the panel temperature rises.