Silvaco Atlas (Silvaco’s TCAD-to-Signoff flow encompasses simulation tools to develop and optimize new semiconductor processes and devices prior to manufacturing)
PV-light-house (excellent) - It provides calculators that simulate various aspects of solar cell operation, a library of refractive index data, links to photovoltaic software, and more
CST (CST Studio Suite Learning Edition introduces you to the world of electromagnetic simulation, making Maxwell’s equations easier to understand than ever )