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Page 1: Solar International Botswana - WEB hosting by - web.co.b · page Solar International Botswana (PTY) LTD. P.O. Box 149 - Gaborone Corner Noko and Nakedi Road Broadhurst Industrial

Solar International Botswana (PTY) LTD.

Solar International Botswana (PTY) LTD. P.O. Box 149 - Gaborone

Corner Noko and Nakedi Road Broadhurst Industrial Plot 6384 Unit E Phone: 3182890 - Fax: 3182891 - Email: [email protected]

Light up your Farm and increase Farm Productivity

Options for Lighting Technologies

There are different ways in providing light. Maybe the best known method in rural areas is using the

light produced by flames. This may be an open fire from burning wood, a candle or a paraffin lamp.

All of these methods have in common that they generate heat, are smelly and form a health and fire

hazard. Because of these reasons people have switched to other methods of lighting. Where there is

access to the Botswana Power Corporation power

lines, electric power is conveniently and

economically used for lighting and powering

electrical appliances. Where BPC coverage is

lacking, electricity may be generated using diesel or

petrol generators. An alternative way of generating

electricity is using Solar Panels.

Some of the advantages is using Solar Electric

Systems compared to other lighting systems are:

� bright and steady light

� it may run your radio and TV

� no monthly electricity bill

� safe, no fire hazards

� no noise and no pollution

� long lasting.

How does a Solar Electric System work?

The sun’s rays can produce energy. When the rays hit a surface this energy may be released in the

form of heat (thermal energy). Solar water heaters, solar cookers and solar dryers harvest this

energy. When special materials are used, electricity is generated when the sun hits the surface of

that material. Solar Panels use this material to convert light from the sun directly into electricity

using the photovoltaic (PV) process. The higher the intensity of the sunlight, the more power is

produced by the Solar Panel. Also a bigger Solar Panel catches more sunrays and therefore

produces more power. In its most basic form, a Solar Electric System consists of four different

components: a Solar Panel, a battery, a regulator (controller) and one or more lights or other

appliances. For 230V lights and appliances an inverter needs to be added to the system. The

function of the different components is briefly discussed below.

Solar PanelThe Solar Panel generates 12VDC electricity directly from sunlight. The Solar Panel is

characterized by its power output expressed in Wp. Sizes vary from 3Wp to 300Wp. Two or more

Solar Panels can be wired together to increase the power output of the system. The electricity

generated by the Solar Panel charges a battery during the day. The panel is normally mounted safely

on the roof or pole by using a carrying structure.

Published in “Farming Magazine” October 2004 Issue

Page 2: Solar International Botswana - WEB hosting by - web.co.b · page Solar International Botswana (PTY) LTD. P.O. Box 149 - Gaborone Corner Noko and Nakedi Road Broadhurst Industrial

page

Solar International Botswana (PTY) LTD. P.O. Box 149 - Gaborone

Corner Noko and Nakedi Road Broadhurst Industrial Plot 6384 Unit E Phone: 3182890 - Fax: 3182891 - Email: [email protected]

2

BatteryAfter the sun has set, the battery provides the electricity that is required. During cloudy days, the

electricity generated by the Solar Panel will be less than during sunny days. However, the battery

can usually store enough electricity to cover up for a few cloudy days, while still supplying

electricity. Most batteries are 12V. The capacity of a battery is expressed in Ah (Ampere-hour).

Batteries can be wired together to increase the Ah capacity. In Solar Electric Systems low

maintenance batteries may be used, that do not require topping up of the electrolyte.

RegulatorThe regulator (also called controller) controls the charging state of the battery. It ensures that

electricity from the Solar Panel does not overcharge the battery and it also ensures that the battery

charge is not drained too much. The regulator often contains an interface with the user by means of

small lights (LEDs) that indicate the state of charge of the battery and system status. Its operating

voltage and current rating characterize a regulator.

AppliancesIt is important to use energy efficient lights with a Solar Electric System. High efficient Compact

Fluorescent Lights (CFLs) are commonly used. Note that CFLs for 12VDC systems are more

expensive than those for 230VAC systems. For a 12VDC system all appliances such as TV and

radio must be rated at 12VDC.

InverterAn inverter changes 12VDC into 230VAC so that AC appliances can be used with the Solar

Electric System. The inverter is characterised by its power rating (Watts) and waveform (square,

modified square or sine wave).

What Appliances can be used?

All kinds of different appliances can be used

with a Solar Electric System such as: radio,

TV, computer, printer, electric fan, cash

register, sewing machine, electric tools (drill,

grinder, etc.), kitchen machines (mixer,

blender, etc.), cell phone charger, refrigerator,

water purifier, etc. Appliances that produce

heat such as electric iron, kettle, stove and

heater require a lot of power and should

normally not be used with a Solar Electric

System.

Apart from the applications discussed above, Solar Panels may also be used to power pumps for

livestock watering and irrigation and electric fences for animal management. Furthermore the

energy from the sun may be used for aeration of ponds for aquaculture and fishing. Also new

developments have shown that solar lanterns may play an important role in pest control.

Page 3: Solar International Botswana - WEB hosting by - web.co.b · page Solar International Botswana (PTY) LTD. P.O. Box 149 - Gaborone Corner Noko and Nakedi Road Broadhurst Industrial

page

Solar International Botswana (PTY) LTD. P.O. Box 149 - Gaborone

Corner Noko and Nakedi Road Broadhurst Industrial Plot 6384 Unit E Phone: 3182890 - Fax: 3182891 - Email: [email protected]

3

How long will the equipment last?

Solar Panels have a warranty on output between 15 and 25 years, depending on the type of panel

used (mono-crystalline, poly-crystalline or amorphous) and on the manufacturer. Batteries should

last three years or more but lifetime depends a lot on the type of battery and its usage. Most

regulators are solid state and should last for over ten years under normal use. It is very important

that the system is not undersized and that high quality components are used in the system since this

will enhance its lifetime.

How does it compare?

Solar Electric Systems are often a cheaper option than new electric lines for providing power to

remote locations. And because they require no fuel and have no moving parts, they are more

economic and convenient to operate and maintain than diesel or petrol generators. In some areas,

the distance from a power source at which Solar Electric Systems become more economical than

new transformers and electric lines is surprisingly short—often as little as a few hundred meters.

These systems are a highly reliable and low-maintenance option for farm lighting, electric fences,

and water pumps. Although current prices for solar panels make them too expensive for most crop

irrigation systems, Solar Electric Systems are economical for remote livestock water supply, pond

aeration, and small irrigation systems.

For more information on Solar Electric Systems contact:

Solar International Botswana (Pty) Ltd.

P.O. Box 149 Gaborone

Corner Noko and Nakedi Road

Plot 6384 Unit E, Broadhurst Industrial

Tel: 3182 890 Fax: 3182891

Email: [email protected]