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Small Mirrors for Solar Power Tower Plants

ARPA-E Award: 
San Francisco, CA
Project Term: 
02/19/2013 to 09/30/2017
Project Status: 
Technical Categories: 
Picture of Otherlab's Small Mirrors for Solar Power Tower Plants
Critical Need: 

Concentrating Solar Power (CSP) systems are a promising clean energy alternative to traditional sources of electricity generation, such as coal-burning power plants. One of the biggest obstacles to the widespread deployment of CSP plants is the fact that they are not cost competitive with conventional sources of energy generation. New CSP technologies must improve energy conversion efficiency while driving down costs in order to make them competitive with traditional power generation methods and help position the U.S. as a leader in the global renewable energy industry.

Project Innovation + Advantages: 

Otherlab is developing an inexpensive small mirror system with an innovative drive system to reflect sunlight onto concentrating solar power towers at greatly reduced cost. This system is an alternative to expensive and bulky 20-30 foot tall mirrors and expensive sun-tracking drives used in today's concentrating solar power plants. In order for solar power tower plants to compete with conventional electricity generation, these plants need dramatic component cost reductions and lower maintenance and operational expenses. Otherlab's approach uses a smaller modular mirror design that reduces handling difficulty, suffers less from high winds, and allows the use of mass manufacturing processes for low-cost component production. These mirrors can be driven by mechanisms that utilize simpler, more readily serviceable parts which decreases system downtime and efficiency. The incorporation of low-cost and highly-scalable manufacturing approaches could significantly reduce the cost of solar electricity generation below conventional solar tower plant technologies.

Potential Impact: 

If successful, Otherlab's approach would reduce the cost of installed solar power tower mirror fields by over 70%.


Cost-effective solar energy would increase U.S. renewable energy use and help reduce our dependence on fossil fuels.


Replacing energy systems powered by fossil fuels would provide an immediate decrease in greenhouse gas emissions, of which electricity generation accounts for over 40%.


Cost-effective renewable energy alternatives would reduce fuel prices and stabilize electricity rates for consumers.

Innovation Update: 

(As of December 2016) 
As part of this project, The Otherlab team has developed a low-cost single-axis tracking system for flat panel photovoltaics (PV) using fluid (air) based actuators. Their approach employs centralized fluidics to actuate the trackers while meeting or beating the tracking accuracy of distributed mechanical motor-based systems.

In March 2016, Sunfolding was spun out of Otherlab, Inc. as a separate entity to focus on commercializing the tracking technology. The team attracted an additional $1 million in funding from the California Energy Commission for the deployment of ~300kW of tracked PV in 50kW phases in Davis, California. At each stage of deployment, Sunfolding is incorporating successive design optimizations to improve the ease of installation and repairs. Sunfolding is pursuing an independent technology assessment of its product and production processes, a bankability requirement for most large-scale PV system customers. 

In addition, Sunfolding was awarded a $2 million SunShot Award to advance their production process to high-volume manufacturing and to drive currently specialized components towards more mass manufacturing solutions. They are currently preparing to raise a Series A venture capital round in 2017. 

Otherlab engineered a low-cost single-axis tracking system for flat panel PV using fluid (air) based actuators. Their approach employs centralized fluidics to actuate the trackers while meeting or beating the tracking accuracy of distributed mechanical motor-based systems. The team determined that a pneumatically-actuated antagonistic bellows design was a feasible and cost-effective solution due to its lower overall mass, lower part count, easy fabrication/configuration, and improved pointing accuracy tolerances.

While the bellows-based drive system represents the core intellectual property developed for Sunfolding’s tracker technology, developing and demonstrating the supporting systems and their integration with the tracker, and ensuring long-term operation was essential to de-risk the platform as a whole. The tracking system passed substantial durability testing, including simulated wind and snow loading and harsh environment cycling. The team then setup ~6kW outdoor tracking array in Sebastopol, California to acquire outdoor test data on a fully assembled system, which has been tracking reliably since August 2015.

For a detailed assessment of the Otherlab project and impact, please click here.

ARPA-E Program Director: 
Dr. Christopher Atkinson
Project Contact: 
Dr. Leila Madrone
Release Date: