Posts Tagged ‘off-grid’


Rural electrification in South Africa

Wednesday 20 February, 2013

Those crazy krauts are @ it again.  The German-South African Chamber of Commerce put on a seminar on rural electrification here in Durban, South Africa, so I sat in on as many sessions as I could.  Most of the content seemed to be provided by Renewables Academy.  This was a comprehensive 4 ½ day seminar, covering photovoltaic (PV) systems, solar resources, cells, modules; batteries & energy storage; electronics, installations, wiring, fuses, loads, applications; off-grid system design & sizing; hydropower systems, & project design.  The featured speakers were Peter Adelmann & Ivan Karau Kisembo.

There are a number of off-grid PV applications:

  • Solar home systems (SHS)
  • Clinics, schools,
  • Rural businesses
  • Tourism
  • Solar water pumping
  • Telecom, 2-way radio
  • Street lighting & signs
  • Back-up
  • Mini-grids
  • Small portable appliances

There are also many different configurations of PV systems:

  • Off-grid & tied to the grid
  • Off-grid wind powered & grid-tied wind powered
  • PV-only off-grid
  • Wind-only off-grid
  • Hybrid off-grid
  • Pico & micro-hydro off-grid
  • Ac- & dc-coupled micro-grids
  • grid-tied PV & wind

It’s important to choose the correct pv module to match the system type.  Modules for off-grid & grid-tied are not usually the same.  Mistakes can be expensive.

Photo-voltaic modules & arrays can be mounted many ways off-grid:

  • Roof
  • Free standing-ground & flat roof
  • Pole
  • Tracks
  • BIPV (building integrated PV)
  • PV slates & tiles

Mounting structures can be made locally out of steel or wood, & aluminum is easy to work with, but expensive.

Batteries can compose 70-80% of the cost of a PV system, so battery management is a key factor.  Charge controllers in off-grid PV systems protect the battery from being overcharged & overdischarging.

Lighting & small appliances are some of the most desirable uses for off-grid PV systems.  Computers, refrigerators, & hvac use too much energy to make sense for off-grid applications.  Adelmann found 100% of rural residents in Ethiopia charged their cell-phones & listened to radios, 30% watched TV, & none used dishwashers or washing machines.  (There they have ample hydroelectric energy-energy distribution is the problem.)  LED’s offer less light, but use little energy.  Incandescents use far more than low-energy bulbs.  Fluorescents last 5-10,000 hours while halogens are cheaper than fluorescents, but not recommended.  How lights are installed can make a big difference in energy consumption.  Areas should be lit with the appropriate level of light & light only areas that require lighting.  Reflectors multiply light.  Avoid wall lights generally as less efficient.

DC appliances, such as lights, tv’s, 2-way radios, fridges, & pumps,  are designed to be run on batteries & are generally more efficient than AC equivalents.  Although DC appliances are more expensive & not easy to find, some mobile home & boating suppliers stock them.  Adelmann worked on a solar project in western China with Shell Solar.  They hired a Chinese company to do the installation.  The Chinese firm then sold the users big TV’s that were big power consumers which overloaded the system, resulting in the project being called a disaster.  People will connect whatever they can to the system, which ruins the reputation of solar energy.

Solar water pumping can be expensive.  Making the borehole can cost more than the PV system.  These are generally more suitable for humans & animals than for crop irrigation.  Mechanical wind pumps are used in South Africa extensively.

Site surveys for off-grid systems are available from renac.  Designing & sizing off-grid PV systems involves the following:

  • Determining the exact energy/power requirements
  • Obtaining information on irradiation @ location
  • Determining output of PV array
  • AC or DC or both?
  • Charge controller?
  • Inverter?
  • Battery type & size
  • DC cable sizes/voltage drop

To plan for sustainable systems that will have a long life, i.e. longer than the 1st battery bank, take into consideration technical, financial, & organizational issues.  Many systems in developing countries, major markets for off-grid systems, last no longer than the original battery bank.  Trying to replace or compete with the grid can be problematic.  According to Mark Hankins of African Solar Designs in Kenya, small PV systems fail for both technical & social reasons:


  • Poor design for
  • Quick sales
  • Lack of thought about system use
  • Poor sizing-too small
  • Lack of money to buy a complete system
  • Poor installation
  • Poorly matched components


  • Lack of plan for energy balance
  • Poor consumer understanding of technology-appliances, batteries, inverters
  • Load creep

He compares small PV systems with electricity from the grid this way:

Small pv system Grid electricity
Power sources multiple Single
Limits many None
Voltage drop possible None
Appliances Select carefully Use any
Energy management necessary Not needed

Here are some best practices for small hydro-electric power construction:

  • Avoid bends in pipe to prevent water velocity loss
  • Use anchors for support @ bends
  • Be sensitive to regional environmental authorities for, e.g. fish migration
  • Pay attention to all these risks:  completion, technological, operations/maintenance, market/distribution, resource, regulatory framework, country, interest, inflation risks
  • Test pipes to the maximum to assure they won’t burst & harm the environment
  • Take all this into account in the design stage

Here are some online resources

sizing tools

commercial systems

solar pumping

renewable energy software

Although the country of Malawi provides a free solar system if a family plants 200 trees, Adelmann’s main thrust was that rural electrification should be left to the private sector in South Africa.  The problem is not that people can’t /won’t pay:  the proliferation of cell-phones proves that.  Many consumers now pay more for energy for less service, for example, for kerosene.  The next issue will be productive use, i.e. how to enable those in the countryside to make money, which requires much higher productivity.  We must improve the countryside to fend off urbanization, but South Africa has no commercial farming.