The goal of my project was to attempt to find the validity of installing photovoltaic solar panels on to the Brown Science Library. In doing so I had to research basic concepts in photovoltaics, and also collect data from Brown Facilities Management as well as field experts regarding performance, energy usage and cost of solar panels as well as the science library itself. After all the calculations, I came up with a few estimated figures showing the expected cost of installation of the project would be upwards of 125,000 dollars, but yearly savings would be around $6,350 on electricity alone. With this in mind, the calculated years before payback would be 19.51 years.
To start, we have to know some basic information about the building:
· Providence’s coordinates are 41.8239N 71.4133W, which is the basis on which we need to design our solar panel angles and shading plans.
· Providence falls into Climate region 3, having 5650 heating degree-days 5650 (over 5500 means long cold winters) and 988 cooling degree-days (fewer than 1500 means short summers). This creates a short, 2-3 month overheating period from mid June to late August. This is when the panels should provide full shading to the windows.
· The orientation of the Sci Li is about 8 degrees off due south, providing an almost negligible decrease in solar performance.
With these facts in mind, we can start talking about design concepts and reasoning. With a southern exposure of over 5000 vertical square feet, and no solar shading interference except for its own design, as well as over 2000 square feet of windows, the Sci Li is a prime candidate for solar shading. It would lower the cost of both cooling, and electricity over the course of the year. Also having 11 identical floors, and 2-3 similar candidates, what ever design is settled upon could be recreated uniformly for the surface of the building. The building currently self-shades part of its window surfaces, and panels would not be placed close to the east and west areas of the building. The center space still has over 40 feet of usable space to place racking and panels.
Paneling installation, especially on large-scale projects, frequently boils down to price per watt at optimum performance. A project is sized by its wattage, and our “sister” project for sake of comparison was an 110,000-watt project that never ended up being purchased by the company. Its price per watt total ended up being $3.22 per watt. With in that there is a breakdown of costs, including the modules, inverters, racking, and balance of systems, which the largest cost of the project as it includes extra equipment, labor, travel and extra design fees. For the Sci Li design, due to economies of scale, and a very specialized installation, the cost of installation was figured to hover around $4.50, which was said to be a very conservative estimate, but still accounts for what ever specialized design and installation would be required for the irregular placement and mechanization of the panels.
With a base per-watt price, it is a simple question of how much space is available for coverage. With 14 panels per the 11 identical floors with 1.21 m2 panels, at 147.22 watts per m2 (derived from a standard size 240-watt panel) we know the Sci Li project to be a 27,500-watt project.
A few steps remain; DC power needs to be converted to AC, an adjustment must be made for the projected horizontal single axis tracking, and then the sun-exposure for the providence area’s effect on the panels production needs to be accounted for. After these figures are calculated we have a projected annual kWh production of 48,818.14. Brown purchases its power by means of auction at a price of 13 cents per kWh, so the total energy savings per year comes out to be 6,346.49. With out even taking into account what savings could be gained from cooling load reduction, the years before payback comes out to be 19.51, a very reasonable figure. The projected payback of the hybrid panels on top of hunter labs due to a lack of grant funding is something to the like of 50 years, and if funded by grants would have been 28, so this project may be a feasible and viable candidate for further research and investment for Brown University.