New Solar Tool Enables Better Business Decisions

Sept. 11, 2018

The best solar panels are the ones that perform reliably for years, but because it’s hard to predict how they degrade over time, shoppers have had a tough time evaluating solar panel systems. This new tool makes more accurate predictions to empower solar panel system decisions.

Which are the best solar panels? That depends on how long they last. Accurately predicting the life of photovoltaic solar equipment is a crucial step in lowering lifetime costs, increasing energy production and boosting buyers’ confidence in solar investments.

New software developed by the Department of Energy’s National Renewable Energy Laboratory (NREL) with SunPower and kWh Analytics is making it easier than ever to determine the lifetime performance you can expect from a solar panel system. 

RdTools draws on years of NREL’s research and applies a new method of evaluating field data on solar production from photovoltaic cells that delivers a faster, more accurate picture of how a solar panel system will perform.

“There’s a high level of interest in this software because it provides user-friendly, accurate, and objective assessments that can help owners make sense of their data,” says Dirk Jordan, engineer and solar PV researcher at NREL. “We spent years building consensus in the industry around a common set of analytical rules. Now PV system stakeholders can learn much more about the performance of their technology and improve decision-making on multiple fronts.”

Read also: ENERGY STAR Scores Update: What You Need to Know

Before RdTools, it was tough to evaluate the degradation of solar PV panels and systems because field performance can be impacted by so many different factors.

Changes in the ambient weather and seasonal conditions affect power output, and sensors that aren’t well maintained may make it look like performance is drifting when the problem is actually that the same performance is no longer measured accurately.

That’s why previous photovoltaic cell evaluations required many years of data to eliminate outliers, scrupulously maintained measuring instruments and scientists to ensure the integrity of the data.

RdTools puts owners and other stakeholders in the driver’s seat by allowing anyone to analyze the performance and degradation of their own solar panel system.

“As more and more solar is deployed, there is an ever-increasing amount of PV performance data available to analyze,” explains Adam Shinn, a data scientist for co-developer kWh Analytics. “For solar investors who seek to understand the long-term financial risks of their energy-producing assets, analysis with RdTools will help them quantify PV durability.”

RdTools is publicly available.

Interested in testing and contributing your insights to improve the software? Email [email protected] or visit

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About the Author

Janelle Penny | Editor-in-Chief at BUILDINGS

Janelle Penny has been with BUILDINGS since 2010. She is a two-time FOLIO: Eddie award winner who aims to deliver practical, actionable content for building owners and facilities professionals.

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