There are many free photovoltaic softwares for PC that can be downloaded for free.
You can choose among the softwares listed here.
The Hybrid2 software package is a user friendly tool to perform detailed long term performance and economic analysis on a wide variety of hybrid power systems. Hybrid2 is a probabilistic/time series computer model, using time series data for Loads, Wind speed, Solar insolation, Temperature and the power system designed or selected by the user, to predict the performance of the hybrid power system. Variations in wind speed and in load within each time step are factored into the preformance predictions.
The System Advisor Model (SAM) is a performance and financial free software designed to facilitate decision making for people involved in the renewable energy industry.
The current version of the SAM includes performance models for the following technologies :
- Photovoltaic systems (flat-plate and concentrating)
- Battery storage model for photovoltaic systems
- Parabolic trough concentrating solar power
- Power tower concentrating solar power (molten salt and direct steam)
- Linear Fresnel concentrating solar power
Skelion, is a Sketchup's plugin to insert solar photovoltaics and thermal components in a surface.
Skelion plugin gives Sketchup the possibility to insert solar panels very fast and make fast renewable solar energy studies.
Includes shadows projection and MAC OS and Windows compatible.
HOMER Legacy is a free computer model that simplifies the task of evaluating design options for both off-grid and grid-connected power systems for remote, stand-alone, and distributed generation (DG) applications.
As of April 14, 2015, HOMER Legacy is available only for the following uses:
1 - Academics and students working on teaching and research, or on energy access projects.
2 - Non-profit organizations working on energy access.
Absolutely no free support is available for HOMER Legacy users, including issues with installation.