Solar Inverter

A fundamental part of every Solar Power set up is the Inverter, it is a piece of equipment that is very important to understand.

After you read this definitive guide you will understand:

• What is an Inverter
• How do they work?
• Grid-Tied & Hybrid Types
• What Size Do I Need?
• Solar Inverter Prices, How Much Do They Cost
• Best Solar Inverters In South Africa

What is an Inverter?

In simple terms this component  converts DC power  (Direct Current) into  AC power  (Alternating Current). DC flows in just one direction , this is ideal for Solar Panels because you need it to simply absorb the sunlight and push it through the system in one direction. This might be an oversimplified explanation but for now, that’s all you need to know for the purpose of this article.

 AC flows in both directions , all of your appliances are powered in this way.

Now we have that out the way let’s move on to the next part.

How do they Work?

The energy from your Panels or your Batteries are fed to the inverter, then, in turn, handles that energy by transforming the DC power to AC.

Grid-Tied & Hybrid Types

The Panels are connected directly into the inverter which then, in turn, plugs into your building electrical box (DB Board).

Hybrids are used for Grid-Tied / Off-Grid / Storage and generator inputs. All different Solar Power applications are possible with Hybrid variations, which is the most versatile option.  Hybrid inverters accept DC and AC power .

Here are the general functions that Grid-Tied and Hybrids typically perform:

• Synchronise to the grid
• Disconnect if the grid goes down
• Use an alternative power source (solar, battery or wind)
• Detect if any power sources are depleted and switch to another
• Monitor power usage

Here are the different types available:

Off-Grid Solar Inverters

Unlike the Grid-Tied options, an Off-Grid variation requires batteries, the power from the Panels charge the batteries directly then the battery power is then inverted to AC from DC batteries.

Off-Grid systems are more complicated, this is due to the extra components you will need such as the Charge Controller, Battery Monitors Circuit Breakers, Surge Suppressors and so on.

Here are the different types of Off-Grid variations available:

Hybrid Solar Inverters

We've left the best for last (my opinion of course), the Hybrid inverter really does of the best of both worlds.

Not only does the Hybrid inverter have all the features of an Off-Grid but it also works well with those who want to fall back to the grid.

Here are the main features:

• For business and residential, it's the ideal choice
• True Hybrids "blend" the energies together (more about that below)
• They come in various sizes, small and large setups
• Gaining in popularity which means the technology is getting better
• More affordable than ever

"Blending" the Energy

Undoubtedly the biggest feature of a Hybrid inverter is the fact that it  uses all the energy sources in the most efficient way  to power your load.

What does this mean exactly?

Just think for a minute that  your house is running 1kw (1000 watts) of power  and in this scenario, your solar panels are struggling to produce the 1kw of power, what happens?

The inverter will realise this and use whatever power it is getting from the solar panels,  let's say 500 watts .

It will not only  use the 500 watts, but it will also pull 500 watts from the battery to make up the 1000 watts total .

And in the event that there is  no battery capacity it will pull the 500 watts from the grid .

The Goodwe inverters are the ideal Hybrid inverters, we highly recommend these.

What Size Do I Need?

This section might get a little tricky because there is a difference between the capacity of the inverter and the output. The capacity speaks to the max DC energy can be fed into the device, while the output speaks to the max AC current you'll be using to power your home. For example,  if you buy a 3kW converter, but your panels are only capable of delivering 1kW, there's an imbalance .

If you plan on adding more panels, then you've made a pretty good investment. However, getting 3kW from your panels while your inverter can only handle a 1kW output seems like somewhat of a waste.  You're not using your system to its full benefits .

Work out what appliances you will be running

Typical households that run the standard number of appliances such as these:

In the example above you can work out that the size you will need to cover these appliances, this equates to 5kw (rounded up).

You might be thinking that this is already a large system, but...

If you one with the dual MPPT output feature you can split that load in 2.

• 2800 watts (2.8kw) for the Tumble Dryer and Washing Machine - Non-essential.
• 2047 watts (2.1kw rounded up) for the rest - Essential.

The ability to have to Essential and Non-essential load outputs allows you to prioritise your energy, bundling them all together is not only going to push up the price of your inverter (because you need a larger one),  it also gives you the option to only use your batteries exclusively on the essential load , driving down the cost of storage needed.

What does this mean? 

It means that your device size comes down, so instead of a 6kw option to handle it the complete load, you can get a 4kw or a 5kw option instead.

Here's an example of a 4.6kw kit that handles the above with some room to spare:

Goodwe – Lithium Storage 3.92kwh – Solar Power Kit

System Specs:

•  NRS approved  (National regulation standards) and on the approved list of inverters for most SA municipalities
• Array size: 2970W (peak hours)
• Est daily production: 16.35kwh
• Storage: 3.96 kwh for daily usage
• Peak load: 4.6kw
• Annual yield: 5886kwh
• Grid-tie / off-grid / grid support

Kit includes 2 x PylonTech US2000 Batteries

View Product Details →

In conclusion...

After working out what size you think you need simply double-check with our team at SolarAdvice to make sure, don't forget that advice is always free.

Solar Inverter Prices, How Much Do They Cost?

Grid-Tied

Here are our Grid-Tied options and their prices, they all vary depending on size and manufacturer.

Single Phase Grid-Tied Options

3 Phase Grid-Tied Options

Hybrid

Micro / Power Optimisers

Best Solar Inverters in South Africa

To name the best pound for pound brand is tricky, each brand does have its strengths and weaknesses depending on its application.

Here are the best brands that we would recommend:

1. Goodwe - this brand is of great quality and a great price
2. SolarEdge - a wide range of options available and great quality
3. SMA - aesthetically great looking and compact
4. Solis - efficient Grid-Tied options
5. Steca - solid German engineering, compact and innovative

Resources:

https://en.wikipedia.org/wiki/Solar_inverter