# pvlib.pvsystem.combine_loss_factors#

pvlib.pvsystem.combine_loss_factors(index, *losses, fill_method='ffill')[source]#

Combines Series loss fractions while setting a common index.

The separate losses are compounded using the following equation:

$L_{total} = 1 - [ 1 - \Pi_i ( 1 - L_i ) ]$

$$L_{total}$$ is the total loss returned $$L_i$$ is each individual loss factor input

Note the losses must each be a series with a DatetimeIndex. All losses will be resampled to match the index parameter using the fill method specified (defaults to “fill forward”).

Parameters
• index (DatetimeIndex) – The index of the returned loss factors

• *losses (Series) – One or more Series of fractions to be compounded

• fill_method ({'ffill', 'bfill', 'nearest'}, default 'ffill') – Method to use for filling holes in reindexed DataFrame

Returns

Series – Fractions resulting from the combination of each loss factor