Low energy and alternative energy lighting.
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An important consideration in alternatve energy systems is low power lighting. Standard filament bulbs produce a lot of heat, which is usually a waste of energy. Two alternatives, CFL and LED are described below.

CFL bulbs

A 12V DC CFL bulb

The circuit from inside a blown 240V CFL.
Note the heat damage, and the number of components..


CFL bulbs (compact flourescent) have received a lot of media attention, and have become a popular way of reducing costs, electricity consumption and carbon footprint.They generally claim to use 20% of the energy (although strangely some manufactures quote this figure as 25%) as compared to filament bulbs, to last longer and are also available in 12V DC versions, seemingly ideal for wind and solar battery systems. However, there are some disturbing facts about CFLs that are less generally known.


Most locally available CFL bulbs cannot be used with dimmers. Well... they can be used, but the dimming function will not work, and the bulbs will last for a far shorter time than advertised, even if the dimmer is kept on the brightest setting. The warranty on these bulbs is also voided when connected to a dimmer.

Filament bulbs are often dimmed when less light is required, which reduces the electricity used.


CFLs contain mercury (about 5mg), which is highly toxic and classified as a hazardous substance. It damages the central nervous system as well as other organs, and leads to acrodynia in children. Some claim it is a cause of autism.

Since CFLs can explode when they fail, they can result in mercury being spread in the living area as a vapour (note that this vapour is far more dangerous than liquid mercury found in thermometers). CFL manufacturers (at least the more responsible ones) recommend wearing vinyl gloves when cleaning up broken CFL bulbs, as well as several other precautions. In addition, when bulbs are discarded, they generally end up in municipal landfills, which results in the mercury contaminating the local ground water.

CFLs still waste energy by producing heat, although less than filament bulbs. About 30% of electricty used by a CFL is converted into heat (as opposed to light), compared to about 90% for filament bulbs. Most of the heat is produced by the electronic circuit concealed in the base of the CFL. Unlike filament bulbs, this circuit is sensitive to heat (it is more likely to fail at higher temperatures) and so CFLs are not suitable for unventilated fittings (such a glass 'fish bowl' fittings).
Carbon footprint

This term refers to the amount of carbon dioxide produced by using something. For a CFL, the amount of electcity saved reduces the carbon footprint. However, the manufacturing process is considerbly more complex than for a filament bulb, and this should be taken into account when considering carbon dioxide production.

This becomes particularly relavant when CFLs are used in environments which reduce their lifetime. (Do manufacturers warn about this reduced lifetime? See below...)

Timer/light sensing switches
As above, most CFL bulbs will have their lifetime considerably shortened when used with automatic light switches.
Frequent on/off
CFLs take about 3 minutes to begin operating efficiently. Energy wise, it is not worth turning a CFL off for less than about 15 minutes before it is turned on again.
Some fittings such as those incorporating a ceiling fan are subject to vibration, and CFL manufacturers do not recommend using their bulbs in such locations. The vibration can casue the electronics in the bulb base to fail.
Manufacturers claim CFLs last significantly longer than filament bulbs. However, there is mounting anecdotal evidence that CFLs do not last as long as advertised. This may be due to differences between 'real life' use and test laboratory conditions - for example expected lieftime ratings of CFL rarely mention how frequently the bulb is turned on and off, and at what temperature they are run while under test. Also, CFLs can become dimmer with age, which can result in them being discarded before they actually 'fail'.
Eskom bulbs
Recently Eskom offered free CFL bulbs in exchange for working filament bulbs. No effort was made to inform people receiving the CFL bulbs about the above issues. The 'Eskom' bulbs also have no manufacturer name or address on them, and most likely came from China, which does not have a good reputation for quality or manangement of hazardous substances in exported goods.
Labelling and packaging of CFLs

Amazingly, many CFL bulbs are sold in South Africa without any warning of the above issues.

As an example, here is the package from a Eurolux 12V DC CFL bulb. It does NOT mention mecury, give instructions for clean up procedures or warn about overheating in enclosed fixtures. Once you have opened (and presumably purchased) the Eurolux bulb, an inner flap contains the slightly obscure warning 'Not dimmable' in four (European) languages. In my opinion, this is a clear case of deceptive packaging/advertising. The Osram package is a little better, in that the phrase about dimming is visible without actually opening the pack.

Local distributors seem to be making no effort to offer safe disposal or recycling facilities.

Click on either package to see a larger image.

The Eurolux pack is also interesting in that omits any mention of the manufacturer, their address, or the address of the distributor.
Does this comply with South African packaging and labelling laws I wonder?

LED lights     
LED lights last over 100 times longer than filament bulbs. They also produce almost no heat, and since they are solid, withstand vibration and shocks. LEDs can run off batteries without the need for a complex circuit, making them ideal for battery, solar or wind power systems. They can also be dimmed.

Individual LEDs are available in a variety of colours, and draw between 3mA and 50mA.

On the right is a standard downlight fitting with 48 LEDs. This draws 90mA at 12V, and produces white light with a greenish tinge. A filament bulb of the same size draws 4000mA! (over forty times more), although the filament bulb is much brighter.

On the left is 1.5watt 24 LED buld in the same housing. It is considerably brighter, twice the price, and produces a whiter light with a very slight blue tinge.

A stainless steel fixture with a 38 LED globe. It draws 100mA at 12V.
A disadvantage is that LED lights are currently expensive, although the prices are falling. Also, because of the limited market, it is sometimes hard to find the desired colour - some can produce a 'cold' bluish light, and some a greenish tinged light. Technology and availability is constantly improving however, and LEDs seem to be the lighting of the future.

UPDATE: These are the latest LEDs. They are amazingly powerful, and use very little current, producing close to 100 lumens per watt of power consumed. The rigid strips are about 400mm long and use 2W. It is also available in flexible stick on strip in lengths up to 6 metres.

They run on 12V, so can be connected directly to a 12V battery, or any 12V supply connected to the mains. Two in series can be connected to a 24V system. They can be bought online here.


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