Optimizing a PV Installation with PVsyst

Why PVsyst?

PVsyst is the most widely used photovoltaic simulation software in the global industry. It integrates weather databases (Meteonorm, NASA, ERA5) covering the entire Moroccan territory and accurately models a PV installation's production over its whole lifetime.

At ERPT, PVsyst is systematically used for feasibility studies and technical calculation notes submitted to banks and financing bodies.

Input Data

A well-simulated PV project starts with reliable data:

• Global horizontal irradiation (GHI): sourced from Meteonorm 8.x. The Ouarzazate region shows a GHI of ~2,200 kWh/m²/year, versus ~1,800 kWh/m²/year for Casablanca.
• Ambient temperature: critical for calculating thermal losses (module temperature coefficient of -0.35%/°C).
• Module characteristics: STC power, efficiency, temperature coefficient, tolerances.
• Network configuration: nominal DC voltage, cable lengths, contact resistances.

Shading Modeling

The 3D shading study is a key step that is often underestimated. PVsyst models near shading (structures, buildings) and far shading (terrain, horizon) and calculates their impact on each row of modules.

For a 20 MWp plant, poor management of row spacing can generate shading losses of 5 to 8%, i.e. several GWh lost per year. Rule of thumb: the height-to-distance ratio between rows is typically 1:2 to 1:3 at Casablanca's latitude (33°N).

System Loss Calculation

PVsyst breaks losses down into several categories:

• Thermal losses: 4-6% depending on mounting type (roof-integrated vs. open-rack structure).
• DC losses: wiring, connections, module mismatch (1-2%).
• Inverter losses: CEC efficiency typically 97-98.5%.
• Soiling and degradation: 1-2%/year for LID degradation, 1-3% for soiling in arid areas.

The target Performance Ratio (PR) is 80-83% for a well-designed Moroccan installation.

Inverter Sizing

The PV-power-to-inverter-power ratio (clipping ratio) is a key economic optimization parameter. A ratio of 1.10 to 1.20 is generally optimal in Morocco: slight clipping at solar noon is accepted in exchange for better yield during low-irradiance hours.

Typical Results in Morocco

On a 1 MWp project in Agadir simulated by ERPT:

• Estimated annual production: 1,820 MWh/year
• Performance Ratio: 81.4%
• Total losses: 18.6%
• Grid-injected energy: 1,818 MWh (after auxiliaries)

These figures, validated by PVsyst and cross-checked with Homer Pro, form the basis of the business plan submitted for bank financing.