Frequently Asked Questions

Learn more about Folsom Labs and HelioScope.

  1. How does HelioScope differ from PV Syst or other performance models?

    The key difference between HelioScope and all other performance models is that HelioScope is a component-based model, compared to other models that are aggregate-based models. In a component-based model, each piece of the system (each module, each wire, each inverter) is modeled separately, and then incorporated into a complete and detailed view of the full system. On the other hand, aggregate-based models treat the system as a single entity, and then handle deviations (such as shading or design variations) with assumptions that approximate the system’s behavior.

    The downside of aggregate-based models is that each behavior must be specifically incorporated and calculated – so if something is not accounted for, it will not show up in the model results. With component-based models, since the mathematics is much closer to the real-world behavior of each component, the results of various system designs can emerge organically.

  2. Who owns my data?

    You do. We believe that any work you do using HelioScope belongs entirely to you, and you should be free to download it, export it, and use it however you see fit. In the meantime, we’ll host all your data for you in the cloud, and hope to provide the best reporting and analysis tools we can to help you understand it.

  3. How do you ensure uptime on the modeling or storage servers?

    HelioScope is run on cloud-based machines with a promised uptime of greater than 99%. In fact, we’re running on two different cloud services on two different continents, with multiple physical locations.

    Formally, this means we’re multiple fault tolerant at the enterprise level. To our customers, this means we guarantee best in class availability.

  4. What types of systems can be modeled with HelioScope?

    HelioScope can model all types of solar PV system designs, including rooftop and ground-mounted systems. Most of HelioScope's users use it for commercial and ground-mounted PV systems, though it can also be used for residential system design.

  5. What third party validation has been done on the model?

    Folsom Labs has worked with DNV GL (formerly BEW Engineering) to ensure that all of our physics modeling is in line with the current state-of-the-art. HelioScope from Folsom Labs is the only performance model to be mathematically validated by a third-party independent engineer.

  6. How can I suggest new features or bug fixes?

    We always love hearing from you! First, feel free to contact the team at Folsom Labs at

  7. How many calculations are done in a standard performance model?

    The HelioScope model runs an 8760 model, which corresponds to one calculation each hour throughout the year (365 * 24 hours = 8760 calculations). However, unlike current performance models, HelioScope doesn’t assume the array is a single PV module - instead the simulation engine performs a calculation for every module in the array for each hour of the year.

  8. What weather files does HelioScope support?

    The environmental algorithm is largely similar to the current industry standards. HelioScope works with all standard weather file formats, including TMY3 and DOE files. HelioScope can also incorporate custom weather if you have measured or premium purchased weather files.

  9. What browsers does HelioScope support?

    HelioScope works on all modern browsers, including Firefox, Chrome, Opera, and Internet Explorer version 9 and later.

  10. How does HelioScope handle a shaded module?

    HelioScope uses a single-diode model for each module in the array. This means that when a module begins to be shaded from an obstruction, it is assumed to lose all of its direct irradiance (DNI), and only generate energy based on its diffuse irradiance.

    This approach enables HelioScope to model mismatch effects properly from shading, since the string IV curve is calculated based on the aggregate of the modules' individual IV curves. It also enables HelioScope to properly model the impact of module-level optimization.

  11. How does the Sketchup integration work?

    HelioScope includes a SketchUp plugin which can be downloaded and installed into SketchUp. The plugin can then be run on any 3D model of shade obstruction to calculate the shade patterns that result from the obstructions. These shade patterns are then used in HelioScope to calculate module-by-module shading.

  12. How does the HelioScope calculation engine determine the operating point of each module?

    HelioScope calculates an array's performance based on component-level calculations, calculating the exact behavior of each module, conductor, and inverter in the array. It then aggregates these calcualtions to determine system effects such as mismatch losses or voltage drop.

    The HelioScope performance algorithm uses an iterative calculation cycle, factoring the IV curves dynamics of each module, compared to the potential loads that the inverter would run at. As the mathematical interactions of the components are highly non-linear, each calculation does not have a singular calculated answer.

  13. Can I import PAN files for my modules?

    Yes, you can import any module PAN files into HelioScope. These can be for modules we don’t yet have in our database, or for specific proprietary PAN files you have created.