While a standard efficiency solar system would offer the lowest initial investment for the client, it would also mean a 25% smaller solar system. In addition, Vista Solar’s cash-flow analysis of a 920 kW high-efficiency Sunpower solar system demonstrated that the high-efficiency option would generate nearly double the carbon and capital savings of an equivalent standard-efficiency system. With a 3.7 year payback and a 20.80% IRR the choice was clear – High-efficiency was the way to go.
In order to maximize the available roof space, Vista Solar employed a 5-degree ballasted racking solution – limiting the required spacing between rows of modules. With PG&E easements running up against the edges of the building, there was nowhere to locate a pad-mounted central inverter the size of a commercial refrigerator, so (32) Advanced Energy 24 kW, 3-phase, string inverters were installed on an existing sight-screen on the building’s rooftop. Due to State and Federal incentives, 59% of the initial investment was recouped in the first year of operation and now “Worldwide Technology Distributor” is on its way to $250K in electricity savings every year for decades to come.