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OpenSolar receives third-party validation of design tool’s accuracy

Written by: Leonard Parker | Solar News | 03rd November

OpenSolar has announced the findings of independent, third-party assessments that validate the accuracy of its solar design tool. By using OpenSolar’s design tool, solar installers will have full confidence they are providing customers with the most accurate PV designs that fit their solar energy needs. Combined with other key features of OpenSolar’s free-to-use platform, including access to a range of state-of-the-art hardware, a portfolio of competitive solar financing options, and on-demand customized permitting proposals, the company enables solar installers to convert more prospects into booked sales while saving time and eliminating the costly licensing fees attached to other solar design and sales platforms.

As part of OpenSolar’s validation process, the company engaged with PV Evolution Labs (PVEL) and the United States National Renewable Energy Laboratory (NREL) to provide independent, third-party assessments of the accuracy of its design tool. The assessments include the following processes and findings.


OpenSolar asked the United States National Renewable Energy Laboratory (NREL), which has been benchmarking shading accuracy of solar design tools for years, to assess the company’s 3D design tool. NREL compared the shading estimates provided by OpenSolar’s remote 3D tool with assessments made on the same roof using a SunEye, the world’s leading hand-held electronic shade measurement tool for on-site assessment.

OpenSolar’s assessment of Sun Access Values was accurate to within +/- 3% The current U.S. market leader was only found to be accurate to within +/- 5%

Site Assessment

OpenSolar engaged PVEL to assess the accuracy of its system-generated site models. PVEL took measurements both in the field and in OpenSolar across a wide range of differently shaped and sized roofs.

OpenSolar’s assessment of scale was accurate to within 1 ⅓ feet 100% of the time (no other tool provides as narrow a tolerance) OpenSolar’s assessment of pitch was accurate to within 4° over 97% of the time (no other tool provides as narrow a tolerance OR such high compliance)

Energy Modeling

OpenSolar’s energy modeling (the conversion of key inputs, including pitch azimuth and shading into the key output: production) is based on NREL’s most advanced System Advisor Model (SAM). The company engaged with PVEL to validate the integrity of OpenSolar’s implementation of SAM, when comparing it to industry standard energy modeling tools like PVsyst or standalone implementations of NREL’s SAM. PVEL found:

OpenSolar’s energy modeling is consistent with standard engineering practices OpenSolar’s production figures are within 0.0%-0.2% of standalone SAM estimates OpenSolar’s production figures are within 0.1%-1.9% of PVsyst estimates

To view and download the full reports visit

“Our assessment of OpenSolar’s software confirms that its implementation of the SAM energy production model engine is accurate and in line with industry standards for residential and commercial projects and its 3D ray tracing calculations of beam shading are as good or better than other available products,” said Ryan Desharnais, chief technical officer of PV Evolution Labs (PVEL). “We also sent measurement teams to a wide range of residential rooftops and verified the accuracy of OpenSolar’s physical site assessments. When taken together, these findings demonstrate that OpenSolar can produce high-quality energy generation estimates for solar projects.”

News item from OpenSolar