natures energy source

different technologies - photovoltaic (pv)

Many people assume that Solar Electric Panels are also used for Solar Water Heating. The technology is very different; Solar Electric panels have Solar Cells, while Solar Water Heating Panels have tubes. The Differences between Solar Electric and Solar Water Heating panels explains the many differences between the two technologies.

the big debate

We look at the key issues and the affordability.

Evacuated tube systems are more efficient than flat panel systems because of the vacuum inside the glass tubes. It allows them to extract heat from the air without direct sunlight, which means that they will significantly heat the water even on winter days without much sun. It's widely believed that evacuated tubes are too efficient for South Africa as they make the water boil, and this can damage the pipes.

Solar geysers can either be gravity fed, or pressurized. With gravity fed systems, the tank needs to be relatively high up, whereas pressurized don't need to be. All solar geyser storage tanks are insulated, allowing the water to stay hot overnight, and for an extra day or so, in case of bad weather.

What favours the flat plates is their aesthetics. They are easier on the eye. But is this the main point? Consider damage to them, in the event that they do get damaged. This means that your system is 'off-line' fo rthe duration it takes to replace or repair - if this is possible.

With vacuum tubes, your system continues to heat water, it only requires that the damaged tubes are replaced - which can take all of 5 minutes. So, for you, which one wins out?

types of solar electric panels

At present, there are two main types of Solar Electric Panels:

The silicon based Photovoltaic Panels (PV panels) are the most common, and are categorized into two main groups; Crystalline Panels and Amorphous Panels. All photovoltaic panels use the same basic principles to create electricity; they convert the photons (heat) produced by the sun into electrons. The rigid crystalline panels are more solid and robust than the flexible amorphous modules, and take up less space, though they are slightly more expensive.

The very first photovoltaic effect was discovered in 1839, and only understood and explained by Einstein in 1921 (The History of Photovoltaics).

The second type is a very new technology, developed by Professor Vivian Alberts of the University of Johannesburg in 2005, known as Thin Film Nano Solar. These panels are more efficient and much more cost effective, as they do not use silicon. Instead they are based on Copper, Indium, Gallium, Selenium and Sulphide (CIGS), which do the same basic thing as the silicon in PV panels.

At present they are not available in South Africa, however Sasol are in the process of building a manufacturing plant in Paarl, near Cape Town, to produce these panels.

This technology is an incredible breakthrough for the solar industry, as the ultra-thin CIGS panels take up around half the space that PV panels take up, and will cost about a quarter of the price.

There are many adaptations found in the solar industry where cells have been integrated into building materials, for example Solar Roof Tiles. These integrated technologies are relatively new, but will definitely become more imminent in the future.

Solar Panels remain the most popular type of Renewable Energy at present because of their reliability and consistency. They produce electricity from photons, which is found in light radiation, which means even on overcast days they will produce something, though they will obviously produce more electricity with direct sunlight.