At Pure Power, our project managers and engineers rely on a suite of photovoltaic simulation tools including PVsyst, HelioScope, and the System Advisor Model (SAM), all developed by industry leaders such as PVsyst, Folsom Labs, and the National Renewable Energy Laboratory (NREL). By leveraging multiple software platforms, we ensure that we are using the most appropriate tool for each specific project scenario—whether it’s for early-stage design, financial modeling, or detailed performance analysis. This approach allows us to deliver accurate, reliable, and tailored results for our clients.
In this post, I’ll walk through how and when we use PVsyst, HelioScope, and SAM, highlighting their unique strengths and applications in different stages of solar project development.
**PVsyst: The Industry Standard for Bankability**
PVsyst is widely recognized as the go-to tool for bankable solar energy modeling and performance assessments. Its long-standing reputation stems from its precision, comprehensive data libraries, and deep integration into the financial and engineering workflows of the solar industry. Developed initially in 1992 by Dr. André Mermoud, PVsyst has evolved over decades to become an essential part of project financing, commissioning, and performance monitoring.
What sets PVsyst apart is its ability to model complex system losses with high granularity—such as module degradation, shading, soiling, wiring losses, and inverter inefficiencies. It also supports probabilistic analyses like P50 and P90, which are critical for risk assessment in large-scale projects. With Version 7.0 released in 2020, PVsyst now handles bifacial systems, advanced shading simulations, and larger project sizes more efficiently than ever before.
This level of detail and accuracy makes PVsyst the preferred choice for owner’s engineers, EPCs, and financiers who require rigorous, audit-ready models. At Pure Power, we’ve used PVsyst extensively for energy yield predictions, capacity tests, and performance guarantees—providing the confidence needed for project financing and long-term operations.
**HelioScope: A Powerful Tool for Early-Stage Design**
HelioScope, developed by Folsom Labs, is gaining popularity as a cloud-based platform ideal for the early phases of solar project development. Unlike PVsyst, which is more suited for detailed financial and technical analysis, HelioScope excels at rapid design iterations, remote site assessments, and preliminary energy modeling.
Its user-friendly interface, integrated with Google Earth and SketchUp, makes it accessible to non-engineers and sales teams. This makes it a great pre-sales tool, allowing developers to quickly generate system layouts, estimate energy output, and prepare proposals without heavy engineering input. In residential and small commercial projects, HelioScope is often sufficient for permitting and financing requirements.
However, for larger utility-scale or commercial projects, PVsyst remains the industry standard due to its depth of analysis and acceptance in financial circles. That said, HelioScope plays a crucial role in the early stages, helping reduce soft costs and accelerating project timelines.
**SAM: A Free Tool for Research and Policy**
SAM, developed by NREL, is a free, open-source software designed for techno-economic analysis of renewable energy systems. While it may not be the first choice for financial underwriting, it’s widely used by researchers, policymakers, and program administrators for feasibility studies, technology comparisons, and regulatory compliance.
SAM supports a broad range of technologies, including PV, wind, and energy storage, making it a versatile tool for evaluating different system configurations. It’s also referenced in key standards, such as the National Electrical Code, where it’s used to calculate maximum PV system currents.
Although financiers typically prefer PVsyst for underwriting, SAM is still trusted as a validated, third-party tool that provides reliable data for planning and policy-making.
In summary, each of these tools serves a distinct purpose in the solar project lifecycle. PVsyst is the gold standard for detailed financial and performance modeling, HelioScope is ideal for early-stage design and sales, and SAM is a powerful resource for research and policy. At Pure Power, we strategically choose the right tool for each project, ensuring both accuracy and efficiency throughout the development process.
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