About Photovoltaic Solar Electricity and Solar Cells in Theory and Practice
The word Photovoltaic is a combination of the Greek word for Light and the name of the physicist Allesandro Volta. It identifies the direct conversion of sunlight into energy by means of solar cells. The conversion process is based on the photoelectric effect discovered by Alexander Bequerel in 1839. The photoelectric effect describes the release of positive and negative charge carriers in a solid state when light strikes its surface.
TYPICAL PV SYSTEM:
Stand-Alone system / Off-grid system
Stand-alone systems are designed to be autonomous and are ideal for remote locations or areas where electricity is expensive or unreliable. Since the system only generates electricity during the day it is necessary to store energy for use during the evening. An inverter converts DC power from the solar array to AC power for household consumption.
Tasol design and install complete solar installations. Because capital outlay on these systems can be large, we strive to design the most economical solution possible.
For solar to work, we have to get the economics right first and then look how we can integrate our solar technologies with other complementary alternative energy solutions to be most effective and have the largest impact on our pocket and the environment. The most important fact to consider here is that energy efficiency is more important than energy generation, for every Rand you invest in efficiency you save about ten Rand in generating equipment.
Energy saving light bulbs, for example, cost approximately R15 versus R3.50 for a traditional incandescent light bulb but they last 10 times longer and are in fact cheaper in the long run : R3.50 x 10 = R35.
A 25W CFL light provides light equivalent to that of a 100W bulb but draws a quarter of the power, so at an electricity cost of R0.96, delivered to your home, the CFL lamp saves R7.20 per 100 hours of lighting or R720 over the course of its lifetime. Multiply that by 10 lights in your home and you’ve saved R7200.
Similarly the size of a Photovoltaic system is dramatically reduced by the smaller load. Energy saving appliances such as refrigerators and freezers are costlier but consume 1/3 the amount of electricity further reducing energy consumption.
A freezer drawing 300W, 24 hours per day consumes 2628kWh each year at a cost of R2522 compared to an annual cost R840 for a an energy saving fridge. The difference in cost when sizing a PV system based on energy saving appliances could be as much R70 000.
Unfortunately the energy efficient process cannot be side stepped. It is always cheaper to save energy than to spend money generating it.
