--- title: What is Panel Efficiency? description: Panel efficiency, or solar cell efficiency, is a way to measure the performance of a solar panel. It describes the ratio of available energy from the sun that is converted into usable electricity by the solar panel.  --- [Skip to content](https://knowledge.projectsolar.com/migration/what-is-panel-efficiency#main-content) English Show submenu for translations ![project solar logo - for light bg.png\]](https://knowledge.projectsolar.com/hs-fs/hubfs/project%20solar%20logo%20-%20for%20light%20bg.png?height=20&name=project%20solar%20logo%20-%20for%20light%20bg.png) Open main navigation Close main navigation - English Show submenu for translations - projectsolar.com projectsolar.com Hello. How can we help you? - There are no suggestions because the search field is empty. 1. [FAQ](https://knowledge.projectsolar.com/migration?hsLang=en) 2. [Solar Basics](https://knowledge.projectsolar.com/migration/solar-basics?hsLang=en) 3. [Solar Insights: Deeper, More Technical Info](https://knowledge.projectsolar.com/migration/solar-basics?hsLang=en#solar-insights-deeper-more-technical-info) # What is Panel Efficiency? ## Panel efficiency, or solar cell efficiency, is a way to measure the performance of a solar panel. It describes the ratio of available energy from the sun that is converted into usable electricity by the solar panel. In other words, if 100 units of energy hit the panel's surface in the form of sunlight, and the panel produces 20 units of energy in the form of electricity, the panel has an efficiency of 20%. If 100 units of energy hit the panel's surface in the form of sunlight, and the panel converts 17 units into usable electricity, the panel's efficiency is 17%. ### How Should Efficiency Factor into My Equipment Choice? Although some labs are working on experimental panels that could be [up to 45% efficient](https://www.nrel.gov/pv/cell-efficiency.html), most residential panels currently on the market top out at around 18-21% efficiency, including the tier-1, black-on-black panels that Project Solar uses.  Higher-efficiency panels are good because they allow more energy to be produced in a smaller space. However, paying more for slightly higher-efficiency panels usually doesn't make sense unless they allow you to fit more panels on your roof, so if a sales rep tries to justify higher prices with a few extra percentage points of efficiency, they might not have your best interest in mind.   - [Solar Basics](https://knowledge.projectsolar.com/migration/solar-basics?hsLang=en#main-content) - [Solar 101: The Fundamentals](https://knowledge.projectsolar.com/migration/solar-basics?hsLang=en#solar-101-the-fundamentals) - [Solar Insights: Deeper, More Technical Info](https://knowledge.projectsolar.com/migration/solar-basics?hsLang=en#solar-insights-deeper-more-technical-info) - [Custom Solar Projects](https://knowledge.projectsolar.com/migration/custom-solar-projects?hsLang=en#main-content) - [Full Service Install](https://knowledge.projectsolar.com/migration/custom-solar-projects?hsLang=en#full-service-install) - [Financial Information](https://knowledge.projectsolar.com/migration/financial-information?hsLang=en) - [Project Solar Power Bank Products](https://knowledge.projectsolar.com/migration/project-solar-power-bank-products?hsLang=en) - [Additional Info](https://knowledge.projectsolar.com/migration/additional-info?hsLang=en) [![Chill listening crop-3](https://knowledge.projectsolar.com/hs-fs/hubfs/project%20solar%20logo%20-%20for%20light%20bg-1.png?width=201&height=17&name=project%20solar%20logo%20-%20for%20light%20bg-1.png "Chill listening crop-3")](https://projectsolar.com) At Project Solar, we aim to make solar so incredibly easy and affordable that it becomes the financially prudent energy option for all homeowners. Copyright © 2026, Project Solar