Investigation of the Viability of a Small Scale SPV System for ResidentialApplications with a Novel Sizing Method

Abstract: Security PV systems or SPV systems represent a slowing growing market share of PV sales with yet have enormous potential. A SPV system is a grid tied PV system with a battery bank, switchbox, and charge controller that allows the system to deliver uninterrupted power to the user in the event of a power outage. This paper uses a newly developed sizing method to investigate to viability of a small scale residential SPV system in Southern California. This novel sizing method was developed for this paper and is based on the idea of under sizing the battery bank by taking into account radiation incident on the PV array during an outage. This under sizing is done using an iterative process to maximize a financial indicator called the Life Cycle Analysis value. A theoretical SPV system is then sized using the aforementioned method and then modelled using NREL's HOMER software and Microsoft Excel. The results of this sizing are a 2.5 kWp PV array with 2 kW inverter and a 1 kWh battery bank. The required initial investment is $11,450. The payback period was 24.8 years and the IRR was ~0%. The system could deliver 30% of the maximum daily load for a period of minimum period of 60 minutes and a maximum period of 70 minutes. The economics of the system reveals that for a SPV system to be cost effective large avoided outage benefits are necessary. This fact implies that SPV systems are more viable for commercial applications than for residential applications.