>Building-Integrated Photovoltaics: A Case Study
>Thirteen out of fifty new homes in an affordable housing development
>in Compton, California were built using building-integrated photo-
>voltaic (PV) roofing tiles. This first project of its kind to incorporate
>building-integrated PV was made possible by $300,000 in funding
>from the California Energy Commission's Emerging Resources Buydown
>Program, the State of California Petroleum Violation Escrow Account,
>and the South Coast Air Quality Management District. The installation
>and monitoring of the systems was sponsored by the South Coast Air
>Quality Management District and the State of California.
>Jan Pepper is the founder and principal engineer at Los-Altos based
>Enertron Consultants, the system integrator for this project. Jan will
>give an overview of the project and report on the performance of the
>systems to date. In addition, Jan will talk about PV in general and how
>people in this area can install systems on their existing homes.
Ms. Pepper began her talk by explaining that she had been working in renewable energy since getting a degree from Stanford in Civil Engineering. She had gone back later for her MBA, and had done things like negotiate windpower contracts with PG&E before becoming a consultant when her first child was born back in the 1980s. Jan currently consults to utilities, state agencies, and independent power producers in renewable energy, and also does sales and marketing of residential and commercial PV systems for a solar company in Sunnyvale.
She then explained some of the unusual constraints for the Compton project. For one thing, since the builder was building affordable housing, he didn't want the PV to add anything to the cost of the buildings. Because of this, she raised money for the project from a number of sources listed above. Also, the developer had not done anything like it before, so there was an education process that went along with the design and building.
The project had been scheduled to go up in the mid 1990s, but it didn't end up happening until 1998. They could have put PV systems on half of the 50 buildings in the development, but several of them were built before the PV panels got final UL Approval, something that is very important to the City of Compton. The solar arrays were sized to fill one south facing roof, so two different floor plans had different arrays, the smaller being a 1.5 KW system, and the other being a 1.8KW system. Both sizes had two inverters in the garage that connected the solar output to the buildings AC electric system.
Jan explained that a year after it went up, the residents were happy with their PV systems. She showed us charts that indicated the PV systems were producing about a quarter less power than the theory had led her to expect. She also had charts of energy consumption for buildings that had the same floor plan, with and without PV systems over a one year period. As expected, the two story homes with PV used less energy than the ones without. This was not the case for the one story numbers, and she didn't know why. Pepper concluded her summary by saying that the developer was so pleased with the experience that he planned to do more developments like this one.
She then showed us a sequence of photos that she had taken to document putting solar panels on her own roof. She said the project was a lot of work, but she had done it because as a professional in the industry she wanted to touch every detail of the process. A homeowner can also install their own system if they have the skills and patience, which could save them about 20% of the cost. However, for most people, it is worth paying a licensed solar contractor to install the turnkey system, including applying for the permits and dealing with PG&E for the approvals.
The economics of a PV system are nice. For a 3KW system, the gross price would be about $30,000.00. Something like half of this can be recovered from rebates that the California Energy Commission gives homeowners for installing PV and tax credits. The payback on the rest can come as soon as eight years down the road, if you install a time of use meter, which costs about $237. The warranty on the panels she used in Compton was 20 years, so homeowners can expect at least 12 years of virtually free electricity once they reach the break-even point.
P.S. For information about solar systems, or if you are interested in purchasing a system for your own home or business, call Jan at 650-949-5719.