One of the issues that has help up large-scale development of photovoltaic technology is solar power efficiency. Such technology has been around and commercially available since the early 1950s, but because of a historically high cost-to-efficiency ratio, it has not been able to compete with energy generated by burning fossil fuels, such as oil and coal. For this reason, the use of CPV, or concentrated photovoltaics, was limited to powering small appliances such as calculators and small garden lights - the latter of which you can purchase today for as little a dollar apiece. Even solar-powered calculators, which were once quite expensive, can now be purchased for under $10.

Part of this drop in cost is due to the fact that the cost of most technologies tend to go down over time. When the television was first introduced in the U.S. in the late 1940s, the cost in terms of today's dollars was around $10,000 - and what you got was a tiny, low-resolution black and white screen. Today, a 36" to 42" widescreen digital TV can be had for a few hundred dollars.

At the same time, new materials and manufacturing methods have made CPV technology far more efficient - meaning that more energy can be generated at lower costs.

Photovoltaic technology depends on materials known as a semiconductor, which is usually some form of silicon. By itself, silicon is not particularly effective in this role, but when mixed with phosphorus or other elements, it is an ideal semiconductor.

Here's where things get a little complicated. As you know, all electrons carry either a positive charge or a negative charge. Likewise, in order to create a working CPV cell, there needs to be a silicon panel that is positively charged and one that is negatively charged. When combined into a single unit, it creates a one-way passage for electrons, known as a diode. These electrons hit the surface of the cell, which in turn creates an electrical charge - and this in turn can be stored in a battery.

While solar power efficiency has been fairly low in the past (which is why it was limited to powering calculators and tiny solar lights), in recent years, efficiency rates of as much as 40% and more have been achieved - an indicator of greater things to come.