Alternative Energy

for Wildlife Ranching

John Ledger

University of Johannesburg

Alternative Energy Options

• Solar Cooking – solar thermal technology

• Solar Water Heating – solar thermal technology

• Solar Photovoltaics – light to energy technology

• Solar cooking – very useful technology but seldom applied. Can reduce

combustion of firewood and/or gas. Maybe pleasing to ‘greenies’ and

overseas visitors

• Solar water heating – essential technology for remote locations. Some

good and durable products made in South Africa

• PV – essential for electricity generation in remote locations.

• Price of modules has fallen drastically in recent years

SOLAR COOKING

The original solar cookers were

called 'box cookers' because they

were literally boxes lined with silver

paper and with a glass lid. Using

black pots, enough heat could be

absorbed from the sun to cook. This

is an original South African design,

the Sunstove, which has been on

the market for a long time.

This is the latest version of the

Sunstove, and the only one

sold nowdays. It can hold two

or three pots. The inner

reflective surfaces are made of

discarded printing plates,

cleaned and polished. The

casing is made from recycled

plastic bottles and it has a

clear plastic cover. More

information is available from

http://www.sunstove.com/

This is an improved box

cooker designed in Germany

and called the K7. It has

extra reflective mirrors to

increase the power, and a

glass lid. The whole thing

folds up into a smallish

suitcase-sized box that can

be safely stored indoors. In a

large field trial in the Northern

Cape, this design was very

popular, and got the

nickname 'Mandela

Microwave'.

The most powerful solar cookers are the

parabolic reflector types. This is a German

designed Koch cooker, the K12. During the

time that GTZ was doing research in South

Africa, these cookers were locally

assembled and I bought this one at the

time. It works extremely well, and the

anodized aluminium reflectors are still bright

and shiny, despite quite a few dents from

hailstones. The whole cooker is made of metal.

Depending on the design of the

reflector, a parabolic cooker may

have the pot/pan holder within the

parabola, our outside. This is a typical

Chinese parabolic cooker, available

from China marts or from

www.sunfire.co.za. The six segments

clip together and give a lot of heat.

Care is needed to protect your eyes

when using parabolic cookers, and

the pots get very hot; sunglasses and

gloves are recommended!

This is the South African answer to

German and Chinese technology, the

'Free State Macrowave'. The frame is

made of galvanised steel water pipes,

and the reflector is fibreglass with

reflective foil glued on. It is made by Willi

Suremann and is extremely efficient. A

handful of twigs at the focal point will

burst into flames after a few seconds. It

probably generates a kilowatt of heat

energy or more, depending on the

season, location and altitude.

People often wonder how you can

cook a meal of two or three

ingredients and keep them hot

until you are ready to eat. The

answer is this 'Hot-Bag' which has

extremely good insulation, and will

keep a pot hot for hours. With

practice, you can also let

potatoes, rice and stews go on

cooking by retained heat long

after you take the pot out of the solar cooker.

With my Wits

MSc students in

2004 after

cooking lunch

for them on a

solar cooker.

Chicken a la

King and rice!

SOLAR WATER HEATING

• A simple black container placed in the sun

will heat the water inside to make it

pleasant for washing

• A length of hosepipe or black plastic piping

laid on a sunny roof or the ground will give

you a hot shower

• But as soon as the sun goes down, the

water in the pipes will rapidly cool down

• This ‘batch heater’ is a steel

tank, painted black, under a

glass cover in a box with

shiny reflective internal

surfaces

• Provides hot water during

day, but cools rapidly at

night

• The ‘donkey’ on the left is

made from old LPG cylinders

and warms water by burning

wood at the bottom

• A functional Solar Water Heater (SWH) must collect the sun’s energy and storeenough hot water for desired use

• The SWH comprises a collector and a storage tank

• The SWH may be of direct design or indirect design

• The thermosiphon principle: hot fluid rises

• In a direct SWH system, the collector is

directly connected to the storage tank, and

the thermosiphon effect results in the tank

filling with hot water after collecting heat in

the collector.

• Direct systems must be freeze resistant for

use in frost areas – if not they can only be

used in frost-free locations

• In an indirect SWH system, a different fluid

(some form of glycol or ‘antifreeze’) is heated

in the collector, rises by the thermosiphon

effect into a jacket around the water tank and

heats the water inside

• Indirect SWH systems are inherently freeze

resistant, but may be susceptible to other

problems and require regular maintenance to

check liquid levels

• In both direct and indirect SWH systems, the

collectors are about 2 m² per 150 litre tank,

comprise copper tubing with copper or

aluminium fins or plates, are painted black

for heat absorption, insulated underneath

and contained in a metal tray under 4 mm

hail resistant glass

• The bigger the collector area, the greater

the amount of solar energy captured

Very old system,

but still working,

at Wereldsend in

Namibia.

Flat plate

collector, tank

insulated with polystyrene.

• A further technical consideration is the evolution of evacuated tube collectors as an alternative to flat plate collectors

• EV tubes come in various forms – because of their design they can collect solar heat longer in a day than a flat plate collector, thereby being more efficient under certain circumstances

• In South African inland conditions they can get TOO HOT and boil the water

• All EV tubes are Chinese imports. Some are excellent, others are poor

Typical evacuated

tube system. Some

tubes are hollow,

double-walled glass

tubes like a thermos

flask. Others have a

‘heat pipe’ inside

and can reach

temperatures of 200 ⁰C

• In an average household, up to 40% of the monthly electricity

cost may be for heating water. But this does vary a lot by

household!

• A solar water heater can reduce this significantly (depending on

usage patterns and weather at the specific locality)

• SWHs have electrical backup

• SWHs usually make good sense

• But beware of the pitfalls of buying a SWH!

• Interior of SA has very high radiation and very low winter

temperatures

• Extremes of weather include hail storms

• Water quality is highly variable across SA

• Locally available materials are desirable

• Should be repairable using basic skills

• Should be durable – for at least 20 years!

Solahart from Australia Spanish system in Namibia

• Designed, developed, patented and

manufactured in South Africa

• All water-bearing parts are copper

• Freeze-protection from high-pressure hose sections

• Electric backup for overcast weather

• Easily to instal and maintain by any handyman or DIY

• Has operated reliably for 27 years in extreme

conditions -Lesotho & Free State, since 1990

The On-Sun Solar Water Heater

Proudly South African!

Neat and attractive design -

all water controls are inside!

Copper tank with unique

arrangement of six 22 mm risers

Standard 150 l system on flat

roof

300 litre system

PHOTOVOLTAICS – ELECTRICITY FROM LIGHT

• Photo Voltaic (PV) cells convert the energy from the photons in light to electrons that create an electrical current

• The PV cells are connected in series to make up PV modules

• The PV modules are arranged in groups to form a PV array

• A PV system generates Direct Current (DC) electricity that can be used in DC appliances

• An inverter turns DC electricity into Alternating Current (AC) at 220 volts to power mains

BETTA LIGHTS

Designed in South AfricaMade in ChinaLead crystal 6 V batteryTwo lights in this kit – up to 8 in othersLow cost housingInformal settlementsTented campsGame ranger outposts

• Etambura Lodge, Orupembe, Namibia

• 1 x 85 watt PV module• 1x Solar controller• 1 x 102 Amp hour battery• 5 x 12 volt, 14 watt compact• fluorescent lamps (CFLs)• Provides good lighting for 5 hours at

30% battery discharge – a wonderful luxury in a remote area!

Water for Wildlife,

Namibia

36 x 80 watt modules generate 2 880 watts

2 x evacuated tube SWH5 kW home system

NorthcliffJohannesburg

• Yellow boxes control system

• Sunny Boy and Sunny Island from

SMA

• 5 000 watt inverter

• Data logging & recording

• Battery bank stores 400 Amp hours at

48 volts = 19 200 watt hours

• Flooded deep cycle batteries 2 V

each, total 24

• LPG gas for cooking and backup

water heating

• Independent of City Power for most

of the time

Electricity from the Sun – Can I do it myself?

• Of course! Basic knowledge of

electricity and wiring will help

• Important to design the system

properly – avoid disappointment

• Many courses and training

available

• Solar modules are at record low

prices at the moment –

oversupply in industry

• LED lighting revolution

• While modules have become cheaper other PV

kit is expensive

• I made my own mounting brackets from steel

• Started with 4 x 200 W monocrystalline modules

NE

• Added 4 x 250 W polycrystalline modules NW

• Two separate MPPT charge controllers

• Inverter 12V/3 kW Victron

• MicroCare 60 Amp MPPT

• Victron 50 Amp MPPT

• 18 Deltec 102 Ah 12V

batteries

• Permanently run all house

lights, TV, office

equipment

• During day, add freezer

and Defy side by side

fridge/ freezer combo

• Get 10 hours use

in summer

DIY SOLAR PV – LESSONS LEARNT

• Start with a 48 V system. I made the mistake of starting with 12 V

• At 12 V you need very thick cables because of high current

• Also need much heavier fuses – I have 400 A fuse installed

• The South African MicroCare equipment is excellent

• The Victron equipment from Holland is also very good

• Be careful of combined MPPT /charger/inverter systems

• There is a lot of Chinese PV kit on the market – some good, others not

• Modules produce DC voltage which can be dangerous

• Battery management is critical – a big part of system cost

• If carefully managed, battery life can be extended

DIY SOLAR PV – LIGHTING & REFRIGERATION

• LED lights have undergone a revolution. It is now possible

to get excellent lighting with a 12 V DC system

• Likewise, energy efficient refrigerators use much less

power than older models and are now much easier to run

off solar

• Appliance marked ‘A+’ are 20% more efficient that those

marked ‘A’

• The Defy chest freezers can go without power for 36 hours – during that period they will warm from – 18 to – 9 ⁰C,

making it possible to run them without batteries

• But would you take the chance?

ALWAYS REMEMBER

In Africa, a little fridge

is better than no

fridge!

THANK YOU