The growing deployment of residential solar PV is opening the way to incorporate storage options so that excess energy can be stored for later use. For example, at the hours of maximum solar production many working people are likely to be away from their homes and storage would allow them to utilize the generated energy on their return.
This is the case at Phoenix, Arizona-based Salt River Project, where sunshine is abundant and there is significant solar PV generation potential. There, solar generation generally peaks in the early afternoon. However, this is often hours before the summer peak, which generally occurs between 3 p.m. and 6 p.m. on weekdays. This is also the hottest part of the day, and around the time when customers are arriving home from work and turning up their air conditioners and switching on appliances. Consequently, solar customers rely on the grid for their energy needs during those peak hours – and those on time-of-day plans also pay more for their electricity in those hours, which translates to higher monthly bills.
Helping customers maximize storage
In order to help customers maximize the benefit of utilizing battery storage with solar PV and decrease their reliance on the grid during peak loads, SRP is working on a project with Arizona State University. ASU graduate students and faculty in the School of Computer, Electrical and Energy Engineering are looking for ways to better align the solar generation to match customers’ energy use by storing the PV energy and then using the stored energy to reduce the residential late afternoon peak load.
For this purpose a PV/lithium-ion battery storage system has been installed on the roof of the Engineering Research Center on ASU's Tempe Campus, along with a control system and a device that simulates SRP's load.
Optimal battery capacity
Researchers also hope to determine the optimal capacity of battery that could help shave the peak load, while saving SRP’s time-of-use customers the most amount of money.
“As batteries become more economically viable, they can help customers save money by reducing energy consumption during peak pricing hours and through this research, we hope to learn how residential solar systems in our service territory impact our system, and determine how battery delivery can assist in peak shaving, frequency regulation and voltage support to further enhance grid reliability,” said SRP Lori Singleton, director of SRP Emerging Customer Programs for Solar, Sustainability and Telecom.
The findings are expected to be available by July 2015.