Photovoltaics

Photovoltaics (PV) is a technology that converts sunlight into electricity. Over the last few years they have become much more efficient and when used in locations with lots of sun can be used to power a normal sized American home almost year around. PV panels are commonly used on long-distance cruising sailboats as a clean source of electric energy for charging batteries, operating electronics and even refrigerating food. PV modules are relatively rugged and durable. Efficiency of PV tends to increase and cost per watt tends to fall over time, making PV increasingly practical and attractive.

There are several types. Of particular note are monocrystalline and thin-film. Tesla is now making roof tiles that mimic standard roof tiles but are PV cells.

Typical Module

• 190 watts
• 61.8" x 37.5"
• 127 watts/m^2
• $900~
• $4.70/watt~

Actual performance obviously depends on the amount sunlight it gets. Some need direct sunlight before the voltage gets close to peak performance. Mono-crystalline modules are better at squeezing out more power in less than ideal conditions.

Tracking

Many off-the-shelf systems exists for tracking the sun for maximum efficiency. A typical tracker arranges several modules in an array, and the surface pivots on a pole not unlike a sunflower.