Source code for pvdeg.design

"""Collection of functions for PV module design considertations."""

from . import humidity, decorators

import pandas as pd




def edge_seal_ingress_rate(avg_water_saturation_pressure):
    """Calculate moisture ingress rate factor.

    Calculates a constant, k, relating the average moisture ingress rate
    through a specific edge seal, Helioseal 101. Is an empirical estimation the rate of
    water ingress of water through edge seal material. This function was determined from
    numerical calculations from several locations and thus produces typical responses.
    This simplification works because the environmental temperature is not as important
    as local water vapor pressure. For the same environmental water concentration, a
    higher temperature results in lower absorption in the edge seal but lower
    diffusivity through the edge seal. In practice, these effects nearly cancel out
    makeing absolute humidity the primary parameter determining moisture ingress through
    edge seals.

    See: Kempe, Nobles, Postak Calderon,"Moisture ingress prediction in
    polyisobutylene‐based edge seal with molecular sieve desiccant", Progress in
    Photovoltaics, DOI: 10.1002/pip.2947

    Parameters
    ----------
    avg_water_saturation_pressure : float
        Time averaged time averaged saturation point for an environment in kPa.
        When looking at outdoor data, one should average over 1 year

    Returns
    -------
    k : float [cm/h^0.5]
        Ingress rate of water through edge seal.
        Specifically it is the ratio of the breakthrough distance X/t^0.5.
        With this constant, one can determine an approximate estimate of the ingress
        distance for a particular climate without more complicated numerical methods and
        detailed environmental analysis.
    """
    k = 0.0013 * (avg_water_saturation_pressure) ** 0.4933

    return k





@decorators.geospatial_quick_shape("numeric", ["width"])
def edge_seal_width(
    weather_df: pd.DataFrame,
    meta: dict,
    k: float = None,
    years: int = 25,
    from_dew_point: bool = False,
):
    """Determine width of edge seal required for given number of years water ingress.

    Parameters
    ----------
    weather_df : pd.DataFrame
        must be datetime indexed and contain at least temp_air, dew_point
    meta : dict
        location meta-data (from weather file)
    k: float
        Ingress rate of water through edge seal. [cm/h^0.5]
        Specifically it is the ratio of the breakthrough distance X/t^0.5.
        See the function design.edge_seal_ingress_rate()
    years : integer, default = 25
        Integer number of years under water ingress
    from_dew_point : boolean, optional
        If true, will compute the edge seal width from dew_point instead of dry bulb
        air temp.

    Returns
    -------
    width : float
        Width of edge seal required for input number of years water ingress. [cm]
    """
    if from_dew_point:
        # "Dew Point" fallback handles key-name bug in pvlib < v0.10.3.
        temp = weather_df.get("dew_point", weather_df.get("Dew Point"))
    else:
        temp = weather_df["temp_air"]

    if k is None:
        water_saturation_pressure, avg_water_saturation_pressure = (
            humidity.water_saturation_pressure(temp)
        )
        k = edge_seal_ingress_rate(avg_water_saturation_pressure)

    width = k * (years * 365.25 * 24) ** 0.5

    return width



# TODO: Include gaps functionality