Derating factors

Solar export limit

To limit the export to the grid (leave this field blank if there’s no export limit; a '0' value input will stop all export to the grid)

Soiling (dirt/dust)

Entered as a % factor (i.e., 95% means a 5% reduction in the annual energy output)

Grid availability

Entered as a % factor (i.e., Grid availability of 99% means there are grid outages / blackouts 1% of the year)

Creates random times when the Grid is not available due to blackouts. During a blackout:

• If there is no battery, or grid configuration is Hybrid only (no backup), then loads = 0 (power outage), and solar export = 0.

• If there is a battery, and grid configuration = backup (internal or external), then loads will be powered from solar and battery. Solar and battery export = 0.

• If there is a battery and grid configuration = backup, but the battery has been depleted, then, loads = 0 (power outage) and solar and battery export = 0.

Surface reflectance

Called as albedo factor - used for system designs with bifacial panels. Select the required surface type based on its albedo factor

Solar access (shading / shade derating)

Entered as a % factor for each month (i.e., 95% in January means a 5% reduction in energy output for the month)

Global horizontal irradiance

How much solar energy falls on a flat surface at the site location

MeteoNorm weather data

Irradiance on an inclined plane

How much solar energy falls on the surface at the tilt angle and azimuth that the array has been set to.

MeteoNorm weather data, and the surface setting on the design page.

Shading

Losses caused by near (trees and buildings) and far (mountains) object shading

Can set a default value in Business Settings > Quote preferences.

Can set a site-specific value in the Solar & Battery Designer page

Soiling

Lost production due to dirt on the panels

Can set a default value in Business Settings > Quote preferences.

Can set a site-specific value in the Solar & Battery Designer page

-1 to -10%

Transmittance

The amount of solar energy that passes through the glass/plastic of the PV module

Based on whether the module has anti-reflective coating (specified in datasheet and recorded in the Product Library)

-1 to -3%

Array converted energy

How much of the available solar energy is converted to electrical energy.

Based on the datasheet values of each panel, and calculated using Cubas equivalent cell method

Cell temperature loss

When PV cells get hot, they are less efficient.

MeteoNorm air temperature records for the site

Mounting method of the PV module (specified in BoS section on Design page)

Module datasheet values

Tolerance

loss/gain associated with manufacturer’s specifications

Datasheet value

0 to 5%

Mismatch

losses due to panel power mismatch. lower for micro-inverters and optimisers

Can be adjusted in BoS section on Design page

-0 to -2%

DC cable & Connector

Voltage drop losses

Based on cable specs in BoS section on Design page, and array current.

-0.5 to -5%

Inverter clipping

Losses when the PV Array DC output power is higher than the Inverter AC max power (oversizing)

Inverter datasheet value, compared with PV output

Inverter efficiency

Losses from MPPT and converting DC to AC

Inverter datasheet value

-2 to -5%

AC cable losses

AC Voltage rise losses on the Inverter Feed cable. (does not consider sub-main,

Based on cable specs in Solar and Battery Designer, and Max inverter current, and export limit.

-0.5 to -3% (ideal)

System efficiency

The total system efficiency

All de-rating factors above.

75-85%