Navigating the sea of technical jargon is sometimes challenging. In this series of blog posts, we will have a look at various areas of a "Solar System" with the intention to better understand it and to size a system according to the need.

The whole concept of a solar installation is to achieve one's personal goal with the installation. That goal, will be different from person to person. In order to design your system, you will need to think about what your expectations are for the system. Do you want an electricity back-up for power outages (such as our old friend Mc Load Shedding)? Or do you want to keep your hard earned cash to yourself by producing your own electricity? "Of course I want to keep my hard earned cash!" you might say, but, let's also talk about capital expense. The products for the installation (inverters, batteries, solar panels and smoke catchers) are unfortunately not free issued items. Hence, an additional goal, or rather, expectation, would be to also consider the budget allocated for the changes you are going to make.

So, we concluded we need to (1) Determine our requirements and (2) we need to acknowledge what our budget is. Next stop, selecting equipment.

Inverters:

Regardless of your requirements, you will always need to use some sort of inverter and some sort of power source (such as batteries or solar panels). An inverter generates the electricity from the power source. There are a lot of different inverters and options available on the market today. Each one has its own advantages and disadvantages. Selecting one, will mainly be determined by your requirements, your installation location and, of course, your budget.

Without over complicating things, let us summarize the very broad type of inverter technology:

This classification on inverters refers to how the "pure sine wave" is generated.

For low frequency inverters, the DC to AC conversion is done by means of utilising a very big, and heavy transformer. Okay, it is a bit more complicated than that, but that is about what one needs to understand. These inverters tend to be leaning towards the more expensive side of what is available on the market. Low frequency inverters are still commonly used today. It has its advantages and disadvantages. I am not going to discuss it now. I would rather like to discuss if an oil leak on a certain brand of British 4x4 is a feature or a problem.

On the other side of the cradle, there are high frequency inverters. Small. Light weight. And affordable. Wow, that is the best thing since sliced Biltong? Right? Right?

High frequency inverters make use of a lot of MOSFETs and IGBTs. These are basically transistor type electronic components that switches open/close states extremely fast, together with INDUCTOR coils, DIODES and CAPACITORS to generate a PURE SINE WAVE from a DC power supply. Wow. That is a lot of technical jargon.

Just like going to the gym, and working out excessively or very fast, one's body heats up and you need to cool down. Similarly, the MOSFETs and their buddies also work very, very fast (at high frequency) to generate the power, it heats up. Heat is dissipated by heat sinks and fans.

PS - using rainwater to cool down the high frequency inverter does not work. We can confirm that. No need to test it out. As well as moist air (especially the Ballito Beachfront Prime Property Moist Air) and dusty environments such as factories, workshops or the barn.

When comparing power output, low frequency inverters can exceed its rated power output up to 300% for several seconds while high frequency inverters can exceed 200% of its rated output for only a small fraction of a second.

How do I choose between low frequency and high frequency?

The major decision factors include the installation environment (clean/dusty air), the type of loads (inductive loads such as machinery, lawn mowers, drills, welders, etc) and the budget. The following guide can be used to aid in the selection process.

Let's complicate things further

The inverter just generates the pure sine wave electricity. It does not yet charge the batteries. In order to charge the batteries, a charger is required. Various charger technologies exist. One can charge batteries from different sources, such as utility power, generator power, wind power and, of course, solar power. All these sources require different chargers. And if you use a 12V battery vs a 48V battery, chances are that the chargers will differ.

A need was therefore created to have a "All-In-One" inverter that can print, scan and copy, oh sorry, I mean can generate electricity, charge the batteries from the utility and charge the batteries from solar panels. That inverter, is known as a "Hybrid" inverter.

Hybrid inverters: Hybrid inverters consist of an inverter, an AC charger, a solar charger, a smart computer to control everything and sometimes other fancy equipment to allow multiple inverters to communicate and work together.

Off-grid inverters: When an inverter does not require a connection to the grid (ie utility power supply), it is known as an off-grid inverter. Hence, if you have a hybrid inverter, that is not connected to the grid, then you have, wait for it, a "Hybrid Off-grid Inverter". When you run an inverter off-grid, then special care should be taken to ensure that the earth/ground wire connection is properly done. A well experienced installer and electrician is recommended to assist in these type of installations. Some inverters, do however, require a grid connection at all times... Introducing...

Grid-tied inverters: These inverters require a connection to the grid at all times. Why would one want to do that? Is the main purpose not to get away from the grid? Why purposely tether yourself to the grid?? Well, for starters, your local municipality will graciously reward you with a small amount for every unit of electricity you feed back into the grid (rates and rules differ between municipalities, so check with yours first). Yes, you can now quit your day job and start earning income from selling back to the council... or perhaps we should do a few calculations first, just to make sure. Of course there is more to be discussed here, but not today.

We have now looked at another few slang words for inverters and the way inverters are classified. The last item on our agenda for inverters is the solar charge controller, which we cover in Chapter 2.

Ready to choose? Our guide What size inverter do I need? walks you through sizing, and you can browse our solar inverters or complete solar kits.

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