Solar power DC to AC power inverters

A battery charger will normally draw power from a mains supply or generator, and charge a battery or bank of batteries, so too does Photovoltaic panels( Solar panels) convert energy from the sun into electricity, which needs to be stored in batteries.

Most electrical appliances and electronic equipment run on 230VAC power, which means in the case of a solar powered system, the power stored in the batteries needs to be converted from 12V DC to 230VAC.

There are DC AC power inverters which are large enough to accommodate this form of electrical supply, drawing of a huge bank of batteries.

 DC to AC power Inverters probably originated because of Solar system-type applications, however it is not the case anymore. All DC AC power inverters that all inverters are not ideal or good for solar system applications anymore.

Many of the available DC to AC power inverters are now used and designed for cost, mobility and various applications- From using a Laptop in your Car , to giving somebody time to watch “ 7de laan” at home, while Eskom is busy sorting its system out….

Why would DC AC power inverters for Solar systems be different then?

Well to explain, let us first tell you some of the assumptions that might fit into your application:

• You are living in a remote area, and you do not have Power Development services
• You want to ideally live and use your electrical appliances as you would be if you lived in or around town or electric grid
• You need power for a game farm, but want to honor the silence of the bush as well
• You have power at your farm house, possibly a generator, but for a few hours per day you would like to run silent (stealth)
• You would like to supply power to your worker houses , and they about 0.5Km from the main supply
• Your power source is so very unreliable…what to do?

All of these kind of systems, require quality products as well as system durability. System durability means, you want to look after your batteries as well as anything else. You might want a power inverter system that interfaces automatically with a generator and possibly other inputs such as Solar Panels & Wind generator.

General experience shows that modified sine wave power inverters are not optimised for proper battery protection, although they do specify that they have a low battery cut out function , this tends to be at voltages 10.5V or in that vicinity, which is fine for occasional battery discharge, but for a permanent fixed installation, this is NOT acceptable. Batteries that reach that kind of discharge, will have their lifetime reduced from a possible 800 Cycles to only 20 0r 30 cycles.

The higher – upper class true sine wave power inverters – do tend to have better battery discharge curves, some power inverters even allow you to choose your disconnect battery voltages .

For system installations of this nature, you would like to have at least the following functions on your power inverters:

• Defined Low battery voltage cut out
• Defined battery over voltage protection
• “Green mode” or load sensing mode, this mode allows the power inverter to go into a sleep mode when no load is connected, and when a light or load is connected – the inverter will switch on- Thus reducing no load system losses.
• AC overloads protection. Make sure if the power inverter is specified for 1kW, that 1kW is actually the continuous rating
• Short period 3x overload rating…thus a 1kW power inverter , must be able to deliver at least 3kW for 10 seconds or so. This is very important to operate fridges, microwaves, motors and some lights.
• Look for a low “no load” power draw. If you have a 1kW inverter, that claims 90% efficiency, but the “no load” power is 200 Watt, then you do not have a good power inverter. The bigger the power inverter, the bigger the no load current would be. If you predominantly have only 200Watt of load, then it doesn’t make sense to operate a 5kW inverter all the time, your total system losses are to high.

If your system , require inputs such as Solar Panels connections, Wind generator, Connection to a generator , then it is necessarily to ensure that these facilities are specified on the power inverter.