Photovoltaic Systems Design
Renewable energy is essential within The Home Depot Smart Home design because it encompasses one of the central ideals of this project: Energy and Efficiency. The Home Depot Smart Home PV system will incorporate PV modules, batteries, possibly a flywheel, a charge controller, and depending on whether we want to sell power back to the grid or power AC appliances, an AC inverter. The goal of the PV system would be to ultimately provide enough power to sustain power usage in The Home Depot Smart Home, or attaining a zero energy house, depending on the amount of funding that we can procure.
There are several different types of photovoltaic technologies with varying efficiencies. Multicrystalline modules are more efficient, less expensive, but susceptible to high drops of efficiency due to partial shading. Thin-film modules are much less efficient, but will not undergo a significant drop in efficiency if subjected to any shade. A newer technology utilizes monocrystalline modules with a layer of thin film over it, which is more expensive than previous technology but achieve a higher efficiency of energy conversion since it utilizes both technologies.
In addition to the choice of photovoltaic technology, it is also important to note the orientation of modules to maximize power output using sunlight. The modules should face true south and reside at a tilt angle of Durham’s latitude of 36° to maximize annual output.
For power storage purposes, a flywheel can be used. However, the price of a flywheel is slightly expensive, and so usage will depend on the amount of funds allocated to this system. Otherwise, a traditional battery bank could suffice. Other components will be needed: DC to AC inverter, Dual Meter Base, Uninterruptible Power Supply Panel, Ground Fault Protection Unit, and an AC Disconnect Unit.
Calculations were made to estimate the cost of a photovoltaic system using different technologies in accordance with an estimated load of 20kWh/day. The cost per watt for the multicrystalline and thin-film came out to be $5.41 and $6.17, respectively. If a system were to use a 3:1 ratio of multicrystalline to thin-film modules technologies however, the system will capitalize on the advantages of each technology while averaging the cost per watt. This ratio will also allow The Home Depot Smart Home to place thin-film modules in places more likely to be subjected to shading or flexible surfaces, while placing the more efficient multicrystalline modules in locations with mostly direct sunlight. However, it is important to note that the modules may contrast with each other and disrupt uniformity in modules, and allow for more complications in integration.
By using solar panels to generate power, the system is environmentally friendly, be able to pay back in the future by selling power back to the grid, and can generate power during power outages.
Presently, the cost of photovoltaic modules are relatively expensive when a substantial amount of power is needed. Also, the amount of power produced is highly dependent on the weather and amount of sunlight on the panels.
Future considerations may include changing the tilt angles or increase the amount of sunlight on the modules to maximize efficiency on a daily basis. This may be accomplished by implementing a tracker system or concentrators. The cost of implementing such additions should be weighed in with the payback in power output of the modules; presently, a commercial tracker and concentrator will be too expensive for a slight increase in efficiency.