sunpeek.core_methods.pc_method.formula.Formula

class sunpeek.core_methods.pc_method.formula.Formula(use_wind)

Bases: ABC

Template class for the equations / formulae for calculating power output, as defined in the ISO 24194:

The formulae are defined in ISO 24194 chapter 5.2.1. The formulae specify 1. how power output is calculated / estimated 2. and what restrictions are applied to data: the criteria in ISO 24194 Table 1 depend on the formula choice.

” # 5.1 Stating an estimate for the thermal power output of a collector field The estimated power output of the collector array is given as an equation depending on the collector parameters according to ISO 9806 and operation conditions. The measured power shall comply with the corresponding calculated power according to this equation. Measured and calculated power are only compared under some specific conditions to avoid too large uncertainties - see section 5.4

The estimate is given by stating the equation to be used for calculating the power output, including specific values for the parameters in equation. The three possible equations are given in the next three subsections. The collector module efficiency parameters eta0_hem, eta0_b, Kb(theta) Kd, a1, a2, a5 [1] and a8 should be based on certified test results. When an estimate is given it shall always be stated which equation shall be used for checking the performance:

a) Simple check, using total radiation on the collector plane when checking the power output (ISO this standard, eq 1). b) Advanced check, using direct and diffuse radiation on collector plane when checking the power output (ISO this standard, eq 2). c) Advanced check, using only direct radiation on collector plane when checking the power output (ISO this standard, eq3)

[1] in the older Solar Keymark data sheets a5 is denoted c_eff “

Methods

__init__(use_wind)
calc_estimated_power(array, aggregator)	Calculate the estimated specific power output of the collector based on the specific formula.
calc_pc_restrictions(plant, resampler)	Check the operating condition restrictions of ISO 24194.
create(formula, use_wind)
get_feedback(fb, array, check_mode)
get_nan_mask(plant)	Check if all sensors required to apply a specific formula are available.

abstract calc_estimated_power(array, aggregator)

Calculate the estimated specific power output of the collector based on the specific formula.

Parameters:

• array (Array)

• aggregator (Callable) – Aggregates single records into an aggregated value, e.g. hourly mean.

Returns:

pd.DataFrame – Other columns are the measurement values of input data used in the calculations, all in unit-aware series.

Return type:

Estimated power output of the collector, unit-aware series compatible to unit [W m**-2]

abstract calc_pc_restrictions(plant, resampler)

Check the operating condition restrictions of ISO 24194. Implement Table 1, chapter 5.4.

Parameters:

• plant (Plant)

• resampler (Callable) – Aggregates single records into an aggregated value, e.g. hourly mean.

Returns:

pd.Series

Return type:

bool mask, True where any of the sensors required to calculate the formulae are NaN.

Notes

From the ISO 24194:

# 6.2 Valid data records Only data records (hourly average values) fulfilling the requirements in section 5.4 are valid. For checking the collector performance, the measuring period shall have at least 20 datapoints. […] All valid datapoints should be used unless it is obvious that errors in the data or very atypical operating conditions occur (omitting valid data points shall be reported and justified).

abstract get_nan_mask(plant)

Check if all sensors required to apply a specific formula are available.

Returns:

bool

Return type:

True where any of the sensors required to calculate the formula are NaN.

Notes

In this PC Method implementation, only data records are used where none of the needed sensor records is NaN.