The price per watt of photovoltaics is still very high. Although PV panels will provide electricity for decades without further cost, their high price still means that for most applications, traditional fossil fuels are a better investment.
PV certainly will not be cost-competitive for utility-scale applications for at least (the very least) a decade, if ever. Much more research is needed to increase the efficiency of solar cells, decrease their price per meter, and improve on their already impressive longevity. In the past, the aerospace industry has privided PV with the support it needed to make incredible progress, but to reach a price-point competitive for more earth-bound applications, PV manufacturers need to find other sources for R & D money.
Right now, PV enjoys great success in several vertical markets, the most lucrative of which is still remote applications. It is crucial that PV find more such niches, both because they will be the breas and butter of the industry for years to come and because they help to convince investors that PV is an active and growing technology.
One of the most promising applications of PV today is supplemental utility generation. A lucky benefit of PV is that it tends to generate more electricity at times of the year when more is needed. In most of North America, for example, utility companies struggle to keep millions of power-hungry air conditioners running in the summer months, when photovoltaic cells are most productive. Many utilities are using PV to help cover peak loads, rather than building entirely new plants. Because PV is so modular in design, these supplemental stations can easily grow from year to year, covering higher and higher loads.
Introduction to Photovoltaics --
John Fraser