> ## Documentation Index
> Fetch the complete documentation index at: https://docs.plantpredict.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Photovoltaic Conversion Overview

export const Metastable = () => <Tooltip tip="Exhibiting metastability: transient performance variation due to reversible changes in material defect states.">
    metastable
  </Tooltip>;

export const MPP = () => <Tooltip tip="Maximum Power Point: operating point on the I-V curve where power output is maximized.">
    MPP
  </Tooltip>;

export const MaximumPowerPoint = () => <Tooltip tip="Operating point on a PV module's I-V curve where the product of voltage and current is maximized.">
    maximum power point
  </Tooltip>;

export const STC = () => <Tooltip tip="Standard Test Conditions: 1000 W/m² irradiance, 25 °C cell temperature, AM1.5G spectrum; the reference conditions for rating PV modules.">
    STC
  </Tooltip>;

export const NOCT = () => <Tooltip tip="Nominal Operating Cell Temperature: cell temperature measured at 800 W/m², 20 °C ambient, and 1 m/s wind speed.">
    NOCT
  </Tooltip>;

export const SeriesResistance = () => <Tooltip tip="Combined ohmic resistance of cell metallization, interconnects, and wiring in the module current path; causes I²R losses.">
    series resistance
  </Tooltip>;

export const LID = () => <Tooltip tip="Light-Induced Degradation: initial power loss from light exposure, primarily due to boron-oxygen defects in p-type silicon.">
    LID
  </Tooltip>;

export const SingleDiode = () => <Tooltip tip="Equivalent circuit representing a PV cell as a current source, diode, and resistances to predict I-V behavior.">
    single-diode
  </Tooltip>;

export const POAIrradiance = () => <Tooltip tip="Solar irradiance on the tilted module surface (beam + diffuse + reflected); drives PV power generation.">
    POA irradiance
  </Tooltip>;

Photovoltaic conversion transforms the effective <POAIrradiance /> into DC electrical power at the output of each DC field. PlantPredict models this process in three stages: module temperature calculation, DC system loss application, and electrical power calculation using the <SingleDiode /> equivalent-circuit model.

## Models in This Section

### Cell Temperature Models

Cell temperature is a primary input to the electrical model—module power output decreases with increasing temperature. All temperature models use the front-side POA irradiance ($G_{POA,front,eff}$) before DC system losses. For monofacial modules this is identical to the effective POA irradiance, but for bifacial modules the contribution of rear irradiance to module heating is neglected. PlantPredict implements four temperature models:

* **[Heat Balance](/models/dc-performance/temperature_heat_balance)** (default): physics-based energy balance model adapted from the Faiman model, with empirically determined conductive and convective heat transfer coefficients. Aligned with PVsyst.
* **[Sandia](/models/dc-performance/temperature_sandia)**: empirical exponential model (King et al., 2004) with coefficients tabulated by module construction type.
* **[NOCT-SAM](/models/dc-performance/temperature_noct_sam)**: physics-based model anchored to the module's experimentally measured Nominal Operating Cell Temperature (<NOCT />), with empirical scaling for irradiance and wind speed (Gilman et al., 2018).
* **[Measured Surface Temperature](/models/dc-performance/measured_surface_temperature)**: uses measured back-of-module temperature from a time series, overriding any of the above models.

### [DC System Losses](/models/dc-performance/dc_system_losses)

Non-ideal effects that reduce power from the theoretical maximum: module mismatch, light-induced degradation (<LID />), module quality variation, and DC health. These are applied upstream of the light-to-electrical-power conversion, as a combined reduction of the effective irradiance before the electrical model is solved.

[DC wiring resistance](/models/dc-performance/dc_wiring_resistance) is modeled within the single-diode model, as additional <SeriesResistance />.

### Single-Diode Models

The electrical conversion uses a single-diode equivalent circuit model, available in two variants: the standard [five-parameter model](/models/dc-performance/5_parameter_model) and a [seven-parameter extension](/models/dc-performance/7_parameter_model) that adds a recombination current term for improved low-light accuracy. The conversion proceeds as follows:

1. **[Parameter Translation](/models/dc-performance/parameter_translation)**: the diode parameters (characterized at <STC />) are scaled to operating irradiance and cell temperature.
2. **[Single Diode Solve](/models/dc-performance/5_parameter_model)**: the single-diode equation is solved with the translated parameters to find the <MaximumPowerPoint />.

## Calculation Sequence

1. **[Module Temperature](#cell-temperature-models)**: Calculate cell temperature from ambient conditions, wind speed, and front-side POA irradiance
2. **[DC System Losses](/models/dc-performance/dc_system_losses)**: Apply combined loss coefficient to effective irradiance
3. **[Parameter Translation](/models/dc-performance/parameter_translation)**: Scale diode parameters from STC to operating conditions (irradiance and cell temperature); add DC wiring resistance to module series resistance
4. **Single Diode Model**: Solve the [five-](/models/dc-performance/5_parameter_model) or [seven-parameter](/models/dc-performance/7_parameter_model) equivalent circuit for maximum power point voltage, current, and power
   DC-applied degradation (Linear DC, Non-Linear DC, LeTID) is applied after DC field aggregation at the inverter level. See [Degradation Losses (DC Applied)](/models/inverter-models/degradation_dc_applied) in the DC Aggregation and DC-AC Conversion section.