Solar Power Back Up

How to create Solar Energy|Power Back Up?  

In order to assist you in understanding the ‘tricks of the trade’ in selecting the correct solution to your specific Back-Up power problems, you need to know your options:

OPTION 1: 

INVERTERS , you probably came aware of inverters in the press during the power blackouts of 2008 (remember them?!!). An inverter is a product which converts battery power to AC electrical power. Inverters range from 75Watt – which is good for a laptop, to well up to 100KW systems.

The most important aspect of backing-up power is to limit yourself to the minimum power consumption as, in so doing, you will also limit your costs! Most people are happy with some lighting, a TV and the ability to operate a computer. If you can keep it down to this, then you will make it a relatively cheap exercise. If you run energy-efficient lights, or LED lights, then your consumption will be much lower and you will thus use less battery power and get longer back-up periods as a result.

How much you power would need, would depend upon the number of appliances and the length of the power cut. 4-5 hours, and you would have no concerns with your geyser, freezer, or fridge – if you play it right. A fridge, like a geyser, will retain temperature for 4-5 hours, depending upon ambient, IF you do not open the doors. So, keep a cooler box next to the fridge, empty in a couple of ice blocks from the freezer, and put in the items you are likely to be needing over the next 5 hours, or so. You can now keep the fridge closed and it will retain its temperature for much longer as a result. Of course, if Eskom is cutting you off for longer periods, you would have to look at also running your fridge off the reserve power, and this significantly increases the costs. 

HOW THE INVERTER SYSTEMS WORK 

In order to use an inverter system successfully, you need to have 3 components:

• Inverter (converts battery 12V DC into 220V A.C.)
• Batteries as a reserve power source (Deep cycle should only be employed)
• Battery Charger (to charge the batteries , when the power comes back on)

Again, as with most equipment, you get the good, the bad..and the decidedly ugly.  Make sure you purchase a reputable make with local support, or your investment could soon become a straight expense!!

A ‘normal‘ inverter has no atomatic transfer switch and does not have built-in charger. This means that you have to switch the unit over your self and keep a charger connected to the batteries to ensure that they are full when you need them. This is the simplest and cheapest method and fine for a domestic application – although for businesses the auto-switch system over is prefered. 

SIZING UP YOUR REQUIREMENTS:

The best way is to check your own appliances and see what you think you can live with (or without!) over a period of say 4 hours. Check our list of appliance wattages on the side menu on the left of this page. This list will give you a good idea of the various wattages pulled by your average domestic, or office, appliance.

Once you have established the appliances and the wattage that they draw, you can use our template to gauge the cost of your specific application.

If you are not sure what type of Inverter you need – be it Sinewave or Modified Sinewave, then this list will also help you. As a rule of thumb, anything with its own power supply (the little black box inserted in a connecting cable!) will run off a modified sine inverter. Compressors (e.g. fridges), motors and pumps should only be run off Sinewave - which is the more expensive of the two inverter systems.

Refer to our list of examples on the side menu for a better idea of your options.

For more information on government solar rebates and solar assistance schemes, visit the Government Solar Power Rebates & Assistance page.

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