SA Response on solar powered homes.

So a frend of mine from Pretoria an Energy Consultant sent me this article after i wrote on Solar:

Solar powered homes

Running your home on solar power

More and more people are beginning to ask the question: “can I run my house entirely from solar power and be independent from grid electricity (ESKOM)?

The answer is YES!

However the initial outlay for such a system is very big – as much as R250 000

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In reality our ESKOM supplied electricity is relativley cheap. In comparison to the cost of alternative energy sources such as solar or gas etc. For this reason it is difficult to justify a high cost in order to create the same power facilities as those offered by ESKOM. To run an average sized home completely on solar power thus needs some energy or power consumption changes to make the whole project more feasible

  • Firstly all incandescent globes must be replaced with CFL – low watt fluorescents and even LED lighting
  • Hot water geysers are seen as a separate entity, as they make use of the heat of the sun to warm water circulating through specially designed heating panels.

Many household appliances are becoming more and more energy efficient, examples are:

  • LED TV’s
  • Laptops
  • Solar fridges and freezers
  • Evaporative air conditioners
  • electric blankets instead of heaters
  • Gas stoves

Below is a complete solar powered system

Please note that the pricing reflected is provides a guideline Here is a scenario of common household power usage and the relevant costs to run such a system with solar power:

SCENARIO

To provide lighting and use of common household appliances:

  1. 20x11W globes average daily use of 5 hrs
  2. Vacuum cleaner average daily use of 30 mins
  3. Hairdryer for 20 mins
  4. Toaster for 30 mins
  5. TV 54cm color for 5 hrs per day
  6. Handrill for 20 mins per day
  7. Food processor for 40 mins per day
  8. Microwave for 10 mins per day

COMPONENTS OF SOLAR SYSTEM

8x80W PV Solar Panels

6x102A 12V batteries

4x20A solar regulators

1 x 6000VA power inverter

Cables and connectors

Bracket mountings

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Adding a fridge and freezer to the equation, which must run 24/7 will add cost in the form of at least four more 80W panels, two more 102A batteries and two more regulators.
Geysers can be converted to solar heating.
Stoves need to be gas, and can be supplemented with a solar cooker.
Then you get independent solar security lights with motion sensors and detachable solar panel, built in battery which is great outside security, never having to worry about power failures.

Starting/planning a solar system for your home can be done in stages:

Let us say that we start with a solar system that will provide power for a TV, DVD, DSTV, a radio and cell chargers and say 10 x 15W lights:

In this first stage we will include an inverter that will accommodate future needs as well.

Stage 1:

  • 4 x 80W solar panels 
  • 2 x 20A regulators 
  • 4 x 102A calcium batteries
  • 1 x 2000W 24V true sine inverter 
  • 4 x panel roof mounts 
  • Cables, connectors and flex 
  • Installation 

Stage 2:

The following components would all be added to those already installed in Stage 1

  • 2 x 80W solar panels 
  • 1 x 20A regulator 
  • 2 x panel roof mounts 
  • Cables, flex and connectors 
  • Installation 
  • 2 x 102A calcium batteries 

Stage 2, would allow the addition of a single door fridge.

Stage 3 could be a duplication of Stage 2, thus allowing the addition of a small chest or single door freezer as well.

Stage 4: Hot water can be generated through the installation of a 200l solar geyser system.

  • A hot water solar geyser system comprises typically of:
  • A thermally insulated hot water tank/geyser
  • Solar heating panels or tubes (Heat collectors)
  • In some cases a small electric pump for circulating the water
  • A small PV solar panel to drive the pump.

Please note that we chose 80W panels for this exercise.

You could also use 160W panels, halving the number of panels,

Or you could use 40W panels and double the number of panels.

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This should give you a good idea of the limitations and costs of solar power / grid-free electricity for your home.

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