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urban energy technical note
Promoting Energy Efficiency in Buildings in East Africa
Urban Energy 17
Technical Note
Solar Home Systems and Solar Lanterns
Globally, approximately 1.5 billion lighting, phone charging, computers • 1 Wp of PV provides enough
people do not have access to electricity, and water pumps. A solar home system electricity for a small light and a
often living far from the electricity is generally designed and sized to supply phone charger.
grid. Household solar systems and direct current (DC) and/or alternating
lanterns allow those consumers access current (AC) electrical appliances. It How Solar Home
to electricity and replace costly, harmful
kerosene lamps and candles. While
consists of a solar module connected to
a solar charge controller, an inverter and
Systems and Solar
solar lanterns play an important role in a battery. The generated DC power is Lamps Work
curbing kerosene usage and providing stored in the battery and converted to AC
Solar home systems and lamps use
light to students, more sophisticated power for supplying to AC loads.
photovoltaic (solar-electric or PV) cells and
solar systems have been developed in
Solar lanterns and solar home systems rechargeable batteries to provide electrical
recent years that provide a range of
(SHS) are helping homes in developing power away from the mains grid. Lamps
functions to customers – from mobile
countries that are not connected to the provide a single light (and sometimes
charging to television usage. While
main grid (off-grid) to have access to phone charging) and are portable. Solar
solar technology has been promoted in
electricity for the first time. home systems are fixed in a home and can
developing countries since the 1970s, it
is only recently that falling prices and Key facts supply several lights, phone charging and
other small appliances.
innovative business models have led to
• Millions of solar home systems and PV cells are made from semiconductor
more widespread adoption.
solar lanterns are in use globally. materials, such as silicon, and generate
A solar home system is a stand- direct current electricity from sunlight.
• High quality lanterns retail for as
alone system, suitable for residential A number of cells can be connected
little as US$10 each.
applications such as home appliances, together and sealed in a weatherproof
casing to form a PV module.
Fig. 01: Components Solar Home System
1
urban energy technical note
Layout of Solar Fig. 02: Solar Home System Design for Home Applications
Home System Description Application
Solar PV cells and modules are specified
SHS 30Wp 2 bulbs of 9W compact fluorescent lamp for 7hr use
by their ‘watt-peak’ (Wp) rating, which
is the power generated under standard SHS 50Wp 9W compact fluorescent lamp for 12hr use
conditions, equivalent to bright sun in
SHS 100Wp 2 bulbs of 9W compact fluorescent lamp for 12hr use
the tropics although they can still work at
lower light levels. Solar home systems use SHS 130Wp 2 tubes of 10W fluorescent lamp + radio or 21” TV. Approximate energy
between about 5 and 100Wp of PV, solar produced 400Wh per day
lanterns between about 0.5 and 2Wp.
SHS 400Wp 3 tubes of 18W fluorescent lamp + radio+ TV + fan, 20L fridge.
The rechargeable batteries store Approximate energy produced 1kWh per day (suitable for small size
electricity, so that it is available at night home)
and on cloudy days, as well as when the
SHS 2000Wp Fluorescent lamp + radio+ TV + fan, large size fridge + water pump.
sun is bright, and they also provide a
Approximate energy produced 6kWh per day (suitable for medium size
stable voltage for the appliances that use
home)
the electricity. Larger solar home systems
normally use lead-acid batteries designed SHS 4000Wp Any appliances except air conditioner. Approximate energy produced
specifically for solar use – standard car 12kWh per day (suitable for general home)
batteries do not last long with the deep
levels of discharge needed in a solar How solar home or hang from the ceiling. Some have small
plug-in PV modules, like solar home systems,
system. Nickel-cadmium and nickel-
metal-hydride batteries have been used
systems and solar but others have the PV cell mounted on
in lanterns and smaller systems because lanterns are used the casing. This cuts the cost, but has the
disadvantage that the whole lamp has to be
they are easier to make portable and The PV module of a solar home system
out in the sun to recharge the battery.
in small sizes. But lithium-ion batteries should be fixed in a position that collects
are rapidly becoming the most popular as much sunlight as possible, ideally on Solar-home-systems and lamps can be
because, with good electronic controllers, an unshaded roof – this also reduces the very reliable and need little maintenance,
they last longer. risk of theft. Ideally, how much a surface although in many countries there are
should be tilted towards the sun depends cheap, poor quality products on the market
An electronic charge-controller protects
on the latitude and what time of year most as well. Users must be trained to check the
the battery from being overcharged
solar collection is required. If a surface is battery, keep the PV module clean and
(when it is very sunny) or over-
tilted at an angle equal to the latitude, it make sure that connectors are secure. Even
discharged (when people try to get
will be perpendicular to the sun’s rays at with careful use, batteries deteriorate and
too much electricity from the system).
midday. The battery is kept indoors with need to be replaced every few years.
Other features can also be built into
the terminals covered so that they cannot
the controller, like different brightness
settings for lamps.
be touched accidentally. The PV, battery,
lights and sockets for appliances are wired
Benefits of Solar
Appliances that are powered directly to the charge-controller. Home Systems and
must operate at the DC voltage of
the battery but an inverter (DC to AC
Customers usually buy solar systems Solar Lanterns
based on the service that they provide The amount of electricity provided
converter) can be included in a larger
(for example: ‘charge one phone and by solar home systems and lamps is
system so that standard mains-voltage
run two lights for six hours each day’). surprisingly small: the 20 Wp module
equipment can be used.
It is up to the supplier to make sure supplies about 50 watt-hours (0.05 kWh)
that there is sufficient PV capacity to per day, and the cell on a small lamp
provide this service throughout the only about one watt-hour (0.001 kWh).
year, and sufficient battery capacity to However, the benefits can be huge.
One advantage with solar energy keep the supply running even when
The main use of a solar home system is
technologies is that they are there are several cloudy days in a row. It
to provide better lighting. Many homes
modular, i.e. they can be tailored pays to use the most efficient lights and
to the power needs of individual without access to grid electricity use
appliances, so LED lights are now most
applications such as electric kerosene lamps, which are dangerous,
commonly used, although larger systems
calculators, small radios, televisions, producing health-damaging fumes and
also use fluorescent lights.
computers, lights or electric pumps. a constant risk of fires. Children are
Solar electric systems can be In a solar lamp, the LED light, battery and particularly at risk, so Ashden winner
expanded easily by adding more charge controller are all in a casing which SolarAid has focused on selling solar study
modules and batteries. is easy to carry and can stand on a table, lamps, which can be used on a table for
2urban energy technical note
homework. Even these smallest solar Dissemination of (ventilation and air conditioners,
lamps give more light than a kerosene
lamp. And it is not just studying that
Solar Home Systems calculators, watches, path lights,
emergency power and battery
There are probably more than ten
is easier and safer with better light. chargers).
million solar home systems in use.
Housework is faster, midwives can deliver
babies more safely, shopkeepers can
Over three million homes have been
supplied through the IDCOL programme
Financing Options
display goods, cattle can be tended and
farm produce sorted and packed.
in Bangladesh, in which Ashden for Solar Home
Mobile phones keep people in touch with
Award-winners Grameen Shakti and
Rahimafrooz Renewable Energy are
Systems
family and friends, and give access to major partners. The work of the REDP The solar home system market is a fast
information, entertainment and mobile led to the installation of over 400,000 developing area of the energy access
money. Being able to charge a mobile systems in rural China. Kenya is the sector, and companies in this sector have
phone at home with solar power enables largest market for solar home systems pioneered some of most innovative
people in off-grid homes to stay connected in Africa, with a large number of financing mechanisms and distribution
to the world, without the cost and effort independent businesses involved and strategies. M-KOPA Solar in Kenya has
of sending phones to be charged in town. about 350,000 systems in use. partnered with Safaricom, the country’s
Solar systems can also power radios, largest mobile network provider; to
providing entertainment and information, The Lighting Africa and Lighting Global launch mobile payment enabled pay-as-
and larger systems run televisions as well. initiatives have helped to improve the you-go solar service using technology
quality of solar lamps and small plug- from d.light design.
Cost and-play systems, and sales have grown
rapidly over the past five years. Ashden
Off.Grid Electric in Tanzania allows its
Costs of solar home systems and lamps customers to prepay for energy generated
winner d.light has sold over 6 million
vary between countries, and have come from their solar systems using a mobile
solar lamps, helped by SolarAid in Africa.
down rapidly over the past decade. payment-enabled subscription service,
In 2014, it would cost approximately reducing the up-front cost burden
Important applications of solar home
US$150 to buy a 20 Wp Barefoot Power M-KOPA’s systems. Systems developed by
systems include:
kit including five LED lights and a phone Azuri Technologies allow customers to
• Rural electrification (lighting and
charger in East Africa, or to have a 20 top-up by purchasing scratch-cards.
power supply for buildings, power
Wp system with three lights and phone
supply to remote locations, potable Each of these business models has the
charger installed on your home by
water for nomadic herdsmen); potential to unlock vast segments of the
Grameen Shakti in Bangladesh. Even
• Water pumping and treatment; market that were previously without
though many families spend more than
• Health care (for storing vaccines and electricity due to the high up-front
US$150 on kerosene and phone charging
medicines in PV refrigerators); costs of the systems themselves. The
in a year, it is a large amount to pay in one
• Communication (PV-powered remote development of leapfrog technologies in
instalment and the up-front cost can be
radio telephones or repeaters); these countries, such as mobile money,
prohibitive. In South Asia, micro finance
• Agriculture (solar pumps for water have allowed businesses to access
has been used successfully for many years
pumping); hundreds of thousands of customers by
to make solar home systems affordable.
• Transport and navigation aids (PV- reducing the burden of up-front costs
More recently there has been growing
powered navigation and signal lights); and transitioning to “energy as a service”
interest in providing systems on a ‘pay-as-
• Security (PV-powered security lights); rather than selling products whose full
you-go’ basis, with businesses like Off Grid
• Corrosion protection; cost remains out-of-reach.
Electric in Tanzania encouraging customers
• Household and office appliances
to pay with their mobile phones.
Fig. 03: Solar Home Systems
LEFT: M-KOPA Solar Home System comprise:
2 LED lights with switches and multiple
brightness settings; 1 LED portable solar torch
light; Phone charging USB with 5 standard
connections; Portable solar radio; 8W high
quality solar panel. (Source: m-kopa.com)
RIGHT: Students using a solar portable light
(Source: offgrid-electric.com).
3urban energy technical note
While much of the entrepreneurial Future of Solar lighting, communications and mobile
activity in East Africa has been focused
on delivering solar kits and solar home
Home Systems & money. System costs will decrease as the
global PV market continues to grow, and
systems, many companies continue to Solar Lanterns the improving efficiency of lights and
make strides developing distribution As earlier stated, approximately 1.5 appliances will provide increasing better
channels to sell solar lights which reduce billion people in the world do not have services (Fig. 04).
the need for kerosene and improve access to electricity, most of them in
the ability to charge mobile phones. developing countries. For example, in Projections indicate that by the year
SunnyMoney, the social enterprise owned Tanzania less than 15% of the population 2030, Africa will still have a non-
by United Kingdom charity SolarAid, are connected to the mains electric grid. electrified population of 698 million,
has recently sold its millionth light in Even in India where three quarters of the compared to around 809 million
sub-Saharan Africa. The company sells population have grid power within reach, people in Asia without electricity. the
a range of lights through promotions the supply is unreliable with frequent and UN Millenium Development Project
in partnership with schools in a number lengthy power cuts in many places. Solar has set out targets for providing clean
of countries, including market leading home systems do not provide the level of efficient energy for reading light and for
products such as Greenlight Planet’s power that the grid offers i.e. they cannot illuminating schools and health facilities.
SunKing Pro, d.light design’s S2, and run a refrigerator or power tools on 50Wp The target for household lighting
Barefoot Power’s Firefly. of PV – but they have huge potential consumption is a minimum requirement.
to provide reliable access to electric
Fig. 04: Solar Home Systems Learning Curve
REFERENCES
1. Breyer, C. and A. Gerlach (2010), “Global Overview on Grid-Parity Event Dynamics”, presentation at 25th EU PVSEC/WCPEC-5 (25th European Photovoltaic Solar Energy Conference
and Exhibition/World Conference on Photovoltaic Energy Conversion), Valencia, Spain, 6-10 September.
2. Karekezi, S. & Ranja, T., 1997. Renewable Energy Technologies in Africa. Zed Books, London.
3. Powering Households. GVEP International. http://www.gvepinternational.org/en/business/powering-households?gclid=Cj0KEQiAiamlBRCgj83PiYm6--gBEiQArnojD0UgqYO-hX5gRRWV
Q46Y7kAVSGoS7UcmN8uBvNMdNIoaArDn8P8HAQ
4. M-KOPA Solar - http://www.m-kopa.com/
5. Off-grid Electric - http://offgrid-electric.com/what-we-do/
6. Wheldon, A. Solar lanterns and solar home systems. Ashden Award. http://www.ashden.org/solar
Executed by UN-Habitat with the support of GEF and UNEP
For more information, please contact:
The Urban Energy Unit
Urban Basic Services Branch
United Nations Human Settlements Programme (UN-HABITAT)
P. O. BOX 30030 - 00100 Nairobi, Kenya The purpose of this Technical Note is to call reader’s attention to new technical issues
Vincent.Kitio@unhabitat.org in the field of sustainable human settlements development. They are not meant to be
www.unhabitat.org/urban-themes/energy/ final or exhaustive. For more information, contact the Urban Energy Unit.
Prepared by Vincent Kitio and Kennedy Muzee
www.unhabitat.org
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