def get_pces( df, suns = 1 ):
    """
    Calculate the power efficiency conversion

    :param df: A Pandas DataFrame containing JV metrics, with pmpp column.
    :param suns: The intensity of the illumination [Default: 1]
    :returns: A DataFrame with pce calculated
    """

    return df.assign( pce = lambda x: x.pmpp* 10* suns )