’s calculator is chosen by according to press release

In a late-July press release, announced they would be adding’s solar calculator to their site.

Solar Power Rocks (SPR) is known for providing educational resources for homeowners looking to go solar. While their yearly state solar power rankings and analysis of solar policy have gone a long way to inform consumers, they are now taking their available tools to the next level with the addition of the calculator.

SPR has been reluctant in the past to add support for a solar calculator, but the overall accuracy of’s calculator made the decision easy:

“‘In the past, we've offered only general examples of the savings homeowners might see by installing solar panels, because there hasn't been an online solar calculator that can model the effect of things like time-of-use electricity billing and shading,’ said Ben Zientara, head of content at SPR.

‘With the calculator, homeowners will now be able to accurately estimate energy production and savings for their own home. It's by far the most accurate and easy-to-use online solar estimator, and we at SPR are delighted to be the second 3rd-party site to use it.’”

The calculator uses Genability to incorporate electric usage profile modeling. This allows the calculator to model the effect of solar on a homeowner’s daily electric usage over the course of a year. Coupled with support for local utility rates (including time-of-use rates), incentives and rebates, and climate conditions, the calculator is the most accurate solar panel calculator available for free on the internet.

In addition to SPR and, the solar calculator is also used on the leading website for consumer solar reviews,