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Lighting Off Grid Energy options

Off-Grid Lighting Technologies

Quality light is a critical –– and often unrecognised –– tool in community development. There are an estimated 2 billion people in the world who rely on inferior lighting systems (i.e. kerosene wick lamps) and pay far more per unit of light than those in the developed world. Without light, rural development is inhibited as people spend their nights "in the dark" and are unable to engage in many types of evening activities that those in the developed world take for granted.

Today, high quality lighting technologies are available at affordable prices for all types of lighting systems. Solar electricity is an ideal, cost-effective power source for many lighting energy requirements.

1.0 Lighting Considerations: What Type of Light do you Need?

There are several general categories of lighting –– each requires different types of light and, often, different types of lamps (also called luminaires). Lighting needs can be divided into 3 general categories, broadly described by the amount of light provided:

Measuring Light Output

The total output from a light source is measured in "lumens".

The brightness of light on a given surface is measured in lumens per square metre (or lux).

Table 1: Lighting Applications and Examples

  Type of Lighting

Description

Lighting Level Lumens/m2

Example Applications

Ambient/Orientation Lighting

Lights an area so that people can see one another and move about.

DIM

5 lux

Sitting rooms

Hospital wards

Bars/restaurants

General Lighting

Provides enough light for detail rendering

 

5 - 50 lux

Reading/studying

Cooking

Security

Shops

Classrooms

Localised or task lighting:

Provides enough light for close work and full illumination.

BRIGHT

50 lux or more

Operating theatre

Close work

Sewing rooms

Although amount of light is important, there are a number of other factors that need to be considered when choosing lighting systems:

2. Off-Grid Lighting Technologies Options

A wide range of options, at a wide range of prices, are available to meet lighting demands. Table 1 presents the most common options:

Table 2: Lighting Options for Off-Grid Rural Households and Institutions

TYPES OF OFF-GRID LIGHTING

  • Lighting Suitability

Fuel/Power Source

Light Output

Lumens

Efficacy

Lumens/Watt

Acceptability for lighting tasks

Fuel-based Lighting Alternatives

Candle

  • Ambient lighting.

Wax

10 l

0.1 l/W

Fire hazard.

Wick lamp

  • Ambient lighting.

kerosene

10-15

0.1 l/W

Fumes.

Fire hazard.

Hurricane lamp

  • Ambient
  • General lighting

kerosene

30

0.15

Fumes.

Fire hazard

Pressure lamp (mantle)

  • General lighting
  • Task lighting

kerosene

1400

1

Fumes. Glare.

Fire hazard

High fuel consumption.

LPG gas lamp

  • General lighting
  • Task lighting

LPG gas

250

1

Fire hazard.

Electric Lighting Technologies

Torch with incandescent bulb

  • Ambient lighting

Dry cells

12V dc

0-20

1-10

Directional light only.

Incandescent bulb (10W)

  • Ambient Lighting
  • General lighting

12V DC

100-150

Low first cost. Widely available. Expensive use of PV power.

Halogen

  • Task lighting

12V dc

Expensive use of PV power.

12V Fluorescent tube

  • Ambient Lighting
  • General lighting
  • Some task lighting

Electricity (12V dc)

150-500

24-50

High first cost. Very efficient. Best matched to PV systems. Need to standardise bulb type.

240 VAC fluorescent tube

 240 VAC

incandescent bulb

240 VAC

Cluster LED

  • Task lighting

Electricity

(DC only)

Extremely high reliability and lifetime.

Solar lanterns

  • Ambient lighting
  • General lighting
  • Task lighting

Electricity

(DC only)

Option 1: Fuel-Based Lamps (candles, kerosene, LPG, white gas, etc.)

Electric lamps are superior in most regards to fuel-based lamps. When grid electricity is available, candles, kerosene lamps and gas lamps are unacceptable for most lighting tasks, barring for emergencies or aesthetic purposes. However, in off-grid situations, fuel-based lamps play a much more important role and have many advantages. They are already in wide use. They are portable. They have low incremental costs. Lanterns and fuels are widely available, and are often locally made. Therefore, planners should not completely discard these technologies to replace them with electric lights.

Fuel-based lighting technologies use the flame from burning fuels to produce light. Light quality varies depending on the lamp technology. These lamps expose users to open flames and should not be used where there is the danger of fire. Some of them produce smoke or CO2, and should not be used in enclosed spaces.

* Wick lamps use wicks dipped in kerosene to produce a flame. Wick lamps are similar to candles in light output, but give off smoke and particulates.

* Hurricane lamps are like wick lamps but enclose the flame in a glass case, making the lamp portable and safer. Hurricane lamps give off much less smoke, and have an adjustable flame.

* Pressure lamps vaporise kerosene and burn it on a "mantle" instead of a wick. The glowing mantle gives off light that is much brighter than other kerosene lamps (in fact the mantle has an intense glare), but which also is noisy and maintenance intensive.

Technology Availability: All types of kerosene lanterns are widely available throughout the developing world. LPG gas lamps are available in developing countries, but less so than kerosene units. Biogas lamps are available in some countries; where unavailable they can be fashioned from conventional gas mantle lamps.

Fuel/Energy Availability: Kerosene is widely available in most parts of the world. In extremely remote areas, diesel is often substituted for kerosene. LPG gas is less accessible in many regions, and it is necessary to check each area before deciding on the technology.

Spare Parts and Service: Spare parts for fuel-based lamps are commonly available where each technology is available.

Optimum Situation: Fuel-based lighting technologies should be considered as a first choice only in situations where infrastructure for PV/RET systems is not available (i.e. no battery replacements) or where there is no capacity to meet the high first costs of PV/RET systems. All off-grid situations should keep a few kerosene or LPG lanterns on hand as back-ups and/or as portable lighting systems.

Option 2: DC Electric Lighting Systems

Electric lighting systems are superior to fuel-based lighting systems because of convenience, cost, safety and overall quality of light output. Small, 12 or 24V DC lighting systems are appropriate for systems of between 1 and 20 lights. They can cost-effectively be powered by lead-acid or nicad batteries recharged by PV, wind, and, in some cases, generator sets or central recharging stations. It is often economical to have a number of dispersed lighting systems rather than a central interconnected system. In general, DC lighting systems should use fluorescent-type light fixtures, as they are much more efficient than incandescent or halogen alternatives. Low-power incandescent lights (3-10 W) can be used for ambient lighting needs. Halogen lamps with reflectors are ideal task lights. Note that PV lighting systems must be properly sized, using the daily energy requirementWind turbines can also be used to power lighting systems.

Table 3: PV Lighting Kit Prices

Component

Typ. Market Price [US$]

PV module 50 Wp (4.5$/Wp)

250-320

Battery 100 Ah (lead-acid)

 65-100

Charge controller

 50-100

Cables, switches & mounting struct.

 40 - 100

Fluorescent lamps 11 W x 4

 100 -140

Commissioning & overheads

 40 -100

System costs (not including taxes)

 $ 580 - 950

PV Lighting Systems

Technology Availability: PV lighting systems and components are now widely available in developing countries and on international markets. See PV light suppliers.

Fuel/Energy Availability: PV lighting systems depend on proper sizing and readily available solar radiation. 4 kWh/m2/day is considered a minimum for economic performance in developing countries.

Spare Parts and Service: PV systems require a minimum level of technical maintenance abilities. They also require a good source of spare bulbs/tubes, and batteries (batteries normally last 2-5 years before replacement).

Optimum Situation: 12V PV lighting systems are best used in small off-grid institutions, commercial establishment and households. DC lighting systems can also power with black and white TVs and radio/cassettes; however, when end-users desire larger appliances (videos, colour TVs, projectors) as well, it often makes sense to step up to 240 AC systems. Because of their simplicity and safety, 12V systems are nearly always better when technical expertise is limited on site. Example rural system types might include: Lighting for 4 rooms in a rural office or house, lighting for 6 classrooms, a laboratory and staff offices in a school.

Option 3: 110/240 VAC Electric Lighting Systems

It may be economically viable in some situations (generally larger systems) to choose 240 or 110 VAC powered lighting systems. AC systems can transmit power long distances (unlike low voltage dc systems). For example, a hospital with 15-20 widely dispersed wards might find it easier to distribute 240 VAC power than to use low voltage DC. Secondly, AC power can run other standard appliances in addition to lights. Thirdly, AC power systems and lighting fixtures do not need to be changed if the site is eventually connected to grid power. Finally, AC power systems easily deliver more power than 12 or 24VDC systems.

Technology Availability: Generators are widely available. Inverter/battery chargers are a fairly new technology, but are considered reliable. They should be carefully chosen by experts.

Fuel/Energy Availability: Fuel availability will be a crucial requirement for situations that use generators.

Spare Parts and Service: The costs of running, servicing and fuelling generators should not be under-estimated. As well, keep in mind that inverters, though reliable, can break; if the system relies on inverters and the inverter goes down, then the whole system goes down.

Optimum Situation: Optimum sites for AC electric systems are large institutions where there are more than 50 lighting points. As well, AC systems are best in places where there is already a requirement for genset to power 110/240VAC appliances or power tools.

For further reading, in addition to those you can access by clicking on the further reading icon below "Lighting" below, try:

"Rural Lighting Services: A Comparison of Lamps for Domestic Lighting in Developing Countries", Willem M. Floor and Robert J. van der Plas

Click on any of the icons below, or click here for further readings on off-grid lighting; or here for off-grid lighting supplier information. If you wish to go to the next module, click here for the "Pumping Module (Number 2)"of this Guidebook, or click on one of the other modules below. Click here for links to visit some good links to other Internet sites.

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