SBIR-STTR Award

Soiling of PV modules leads to significant loss of energy and revenue, but routine cleaning is also costly. Therefore, there is a need for field-deployed soiling sensors, to enable PV system performance assessment and optimization of cleaning schedules. We propose to continue the development and evaluation of proprietary optical soiling sensor technologies disclosed in U.S. Patent Applications 62/652,955 & 62/690,086 filed by NREL, which are intended to provide low-cost, maintenance-free sensors. Our goal in Phase I is to determine the technical and commercial viability of the NREL technology. Using a combination of indoor and outdoor testing, we will address at least the following key technical points: light source stability, response to soiling particles with different optical properties, resilience to soiling of the sensor?s optics, and performance of the technology in outdoor environments.The commercial applications of the project include the possibility to provide low- cost accurate soiling measurements for PV power plants so they can optimize their operations. This will lower the cost of PV power generation and make it more widely available. Phase I will determine the viability of the technology and Phase II will commercialize the technology.

The declining cost of solar technology for electricity generation has led to a dramatic increase in its deployment. However, the intermittent nature of solar photovoltaic generation presents a significant challenge for grid operators, and it is widely recognized that co-located, inexpensive and reliable energy storage is required to promote the stability and operational flexibility of the grid. Ideally, such systems would be fully integrated in order to provide an efficient and inexpensive means of storing energy from a photovoltaic installation on a time scale ranging from a few hours to several days. This project takes advantage of a recently developed organic redox flow battery that uses a single active material in three different oxidation states to achieve low cost, scalable, robust energy storage. By using a single active material, the ion-selective normally required in flow batteries can be replaced by an inexpensive porous separator. Moreover, the combination of much higher cell voltages with the ability of Jolt’s system to deliver two electrons per molecule provides significant improvement over conventional flow batteries in both energy density and power density. Phase I delivered a fabricated 12 Volt multi-cell flow battery stack incorporating a simulated photovoltaic array and a fully functional control system. Specific tasks achieved included: measure and optimize single cell operational parameters for different cell geometries; optimize control system charging with the variable output of a photovoltaic array; optimize the control system to govern dispatchable power generation. Based upon the successful completion of the Phase I project, an opportunity for a larger Phase II pilot installation has already been arranged. This pilot will allow a more thorough analysis of the operational costs, use cases, and overall “real world” performance of the system. The ultimate objective of the project is the commercial implementation of these systems to provide efficient energy storage for dispatchable solar generation, thereby significantly improving grid stability and fostering the increased adoption of renewable energy resources. The Jolt organic redox flow battery offers a solution for the most critical needs of stationary electric storage, including the top three needs identified from interviews with solar industry practitioners, utilities, and owners: time of day load shifting, backup power, and peak shaving. The Phase II project will provide potential customers with important technical, cost and performance data obtained under practical conditions.