With the growing need for energy, alternative energy sources are being developed and refined. Solar energy is an attractive alternative as it is a relatively clean, renewable source of energy. Solar energy has been utilized in various ways such as for direct heating, electricity production and biomass production.
The energy needs by the year 2050 have been projected to be 28 TW in comparison to the currently used 11 TW. Although solar energy could probably provide a significant share of the required energy, it needs to be made available at a reasonable cost. The price of a 100 W silicon panel for converting solar to electric energy is 350 to 400 US dollars. However, this is too expensive to be practical. The exponential growth of about 40% per year has been mostly driven by huge subsidies from the government.
A solar cell is a device that converts solar energy directly into electricity. The first generation solar cells transform light energy by using crystalline or amorphous silicon as inorganic solid-state material. The first generation cells are very expensive due to the cost involved in purification and production of the solar cells. The second generation solar cells make use of thin film as the core of the solar cell. The 3rd generation of solar cells is inspired by photosynthesis and has shown the potential to be more cost effective.
Dye- sensitized solar cells have been used to generate a potential gradient to generate electricity. These solar cells have shown good performance in diffuse light and have low investment cost to initiate production. The dye stability has been improved upto 15 years in sunlight by continued research. Titanium dioxide has emerged as the semiconductor of choice due to its abundance, non-toxicity, cost and compatibility.
Solar cells are facing the problem of scalability as the third generation cells are not being cost effective at large scale. Further developments in the field would be focused on better conversion efficiency and cost of production and maintenance.
A biological model such as living organism capable of generating the potential gradient could be a idea worth exploring as the cost of production could be reduced. Many organisms are known to be capable of maintaining potential gradients. The challenge would probably be to combined the potential gradients of individual cells to get a net higher potential.