Electrical

BASIC SOLAR KNOWLEDGE & ALTERNATE POWER – PART 3

Author – Mark Blomeyer 

In Part 1, we touched on Solar geysers and Solar for electrical uses.
In Part 2, we touched on three ways to heat hot water using solar power.

I’m now going to touch on the different types of solar panels on the market for producing power.  I don’t want to get all High Tech

For Industrial or Commercial use most suppliers will tend to supply Monocrystalline solar panels.  They are made from pure silicon wafers.  They are more efficient and more expensive.  Their efficiency rate is in the region of 20%.  The Multicrystallines or Polycrystalline panel as it is also known is made up of fragments of silicon that are melted together then sliced into wafers.  They are a very popular panel.  Most homes have these panels as they are relatively cheap and the efficiency though not as good as the Monocrystalline are still efficient.  Their rate is between 15% and 17%.

The thin film is not popular.  It’s made up of a variety of materials.  The most common being Cadmium Teluride.  They are expensive yet not as efficient as the Monocrystalline or the Multicrystalline, campers prefer this type of Solar panel.  There efficiency rate is 11%. 

In order for a panel on the roof to charge the batteries a regulator also known as a charge controller is installed between the panels and the batteries.  What this does as its name implies is it regulates the voltage flowing from the solar panels to the batteries.  On a good sunny day a 12 Volt solar panel can produce up to 18 volts.  This would boil the liquid in your 12 Volt battery destroying it. At night the panel acts as a globe.  It draws power out of your battery.  The regulator will prevent this from happening.  It’s very important to connect the regulator to your battery first.  By doing this the regulator can then determine if you have a 12 Volt, 24 volt or 48 Volt battery system.  Once it has determined that, only then can you connect the Solar panels to the regulator.  By doing it this way you are sure to get 12 volts charging your 12 Volt battery system.

In South Africa the most efficient direction to position solar panels is facing North as the sun crosses the equator from East to West.  We get the most out of the sun from 10.00am to 3.00pm.

A problem we often come across is the size of cables being used linking the solar panels to the batteries.  If the cables are too thin efficiency is lost in volt drop.  It’s important to know what size cables to use.

Another factor that influences the efficiency is temperature.  As the panels heat up from the sun the voltage increases.  Its good practice to raise the panels on a frame or rails.  This allows air flow to flow under the panels.  This does help to reduce temperatures.

There are a variety of inverters on the market.  From modified sine wave inverters to pure sine wave invertors and grid tie invertors.  Again I don’t want to become too technical.  Modified inverters are at the bottom of the rung.  They are the cheapest.  The power that this inverter produces is of a poor quality.  Instead of it producing pure sine waves, the way Eskom does, it produces a square stepped up wave.  This is fine for lights and small loads.  It should not be used for running motors like fridges.  The fridge motor will get hot and has the chance of burning out.

The next level up is the pure sine wave inverters.  This producers the same power as Eskom.  These inverters can be used to power all sorts of loads.  Here one needs to be careful not to exceed the rated load of the inverter.

In this category is the grid tie invertor.  These are also pure sine wave inverters.  The difference is they do not have the battery back up as the standard inverter does.  How they work is as long as there is sun they will harvest the power from the panels and feed this power into your homes.  The catch is they only work during sun hours and Eskom has to be present.  As soon as the Eskom power dies so does the grid tie inverter.

I hope you all are enjoying these articles.

In my next article, I will touch on generators and gas geysers.

5 thoughts on “BASIC SOLAR KNOWLEDGE & ALTERNATE POWER – PART 3

  1. Thank you for the interesting article on the basics. I am interested in a system I can build onto-as finances allow. With the objective of going totally off grid -the price of “quality” batteries and their efficiency seem to be a limiting factor- what type of batteries would you use if you installed a system for me and what would they cost per battery?
    Thank you!

  2. I am enjoying your dissertations.
    I live in Ambervalley and we have no alternative support whatsoever. I have seen the odd sytem being installed in the last while .
    I am also the Estate manager at KwaWula the Game estate just out of Howick. 54 good homes and few of them are equipped to survive the probable onslaught.

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