---
title: "PV conversion model"
slug: "conversion-inside-pv-modules"
description: "Explore the energy conversion process in PV modules, including the Single Diode model, cell temperature, and module degradation for optimal solar performance."
updated: 2026-06-18T08:04:25Z
published: 2026-06-18T08:04:25Z
canonical: "kb.solargis.com/conversion-inside-pv-modules"
---

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

# PV conversion model

**In this document**

This article explains how the PV conversion model transforms cell-level irradiance and temperature into DC electrical output. It covers the De Soto Single Diode Model and its five parameters, the transient thermal correction applied to cell temperature, and how individual cell IV curves are aggregated up through submodules, modules, and strings to the inverter input.

## Overview

The PV conversion model simulates the transformation of sunlight and temperature into DC electrical output at each inverter input, serving as a crucial bridge between the [optical simulation](/v1/docs/argus-optical-simulation-overview) and the rest of the electrical system. For each time interval, it uses the cell-level Global Tilted Irradiance (GTI) heatmap and temperature data to calculate the current-voltage (IV) characteristics on the DC side for each inverter input.

## Single Diode Model

The **Single diode equivalent circuit model**, also known as [De Soto's "Five Parameter" model](https://doi.org/10.1016/j.solener.2005.06.010), is used in Solargis Evaluate to simulate the conversion of solar irradiance into electricity within PV cells.

The Single diode model requires five key parameters to describe the **current-voltage (IV) curves** of PV cells. These parameters are typically acquired at Standard Test Conditions (STC):

- **Modified ideality factor**
- **Diode saturation current**
- **Light current (photocurrent)**
- **Series resistance**
- **Parallel resistance**

These parameters, along with the Global tilted irradiance (GTI) and cell temperature, are used to generate the IV curves for each PV cell.

> [!TIP]
> **Note**: When calculating the IV curves of bifacial PV modules, the bifaciality factor (as specified in the [PV components catalog](/v1/docs/pvcc-introduction)) is applied to the rear-side GTI to account for the decreased efficiency of the PV module's rear side.

**Advantages of the model**

The use of the Single diode model in conjunction with [raytracing](/v1/docs/incident-irradiance#ray-tracing) allows for **detailed analysis of shading conditions** at the level of **individual PV cells**. This enables precise simulation of the electrical performance of PV modules under various environmental conditions.

### Transient thermal correction model

To calculate the cell temperature, we use the [Transient thermal correction model](https://ieeexplore.ieee.org/document/9095219) to account for the thermal inertia of PV modules by smoothing 1-minute temperature data with a weighted average over the previous 20 minutes. In the case of 15-minute data, only the current and previous time slots are considered. As a result, module temperature changes more gradually, reflecting real-world behavior and improving the accuracy of performance predictions.

## IV curve aggregation

Solargis Evaluate PV simulator calculates the **IV curve for each PV cell** in the power plant, based on De Soto's model. The IV curves of the PV cells are then summed together for the submodules, PV modules, and strings, following the power plant electrical layout and electrical circuit physics. The string's IV curves then enter the [next stage of the PV yield simulation](/v1/docs/argus-electrical-simulation-overview#inverter-clipping-losses).

Using this approach, the performance of each string in the PV power plant is accurately calculated, reflecting real operating conditions such as partly-shaded PV modules. This means that no assumptions on partial shading performance have to be made, which is sometimes a requirement in other PV yield simulation software.

## Further reading

- ["Improvement and validation of a model for photovoltaic array performance"](https://doi.org/10.1016/j.solener.2005.06.010). W. De Soto, S.A. Klein, and W.A. Beckman. Solar Energy, 2006.
- [Transient Weighted Moving-Average Model of Photovoltaic Module Back-Surface Temperature](https://ieeexplore.ieee.org/document/9095219). M. Prilliman, J. S. Stein, D. Riley, G. Tamizhmani.