Solar Inverter Guide

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?

Hybrid string 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.

Solar Inverter diagram

You get three main types of Inverters you can use, each one functions a bit differently to the other:

Grid-Tied, Off-Grid & 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:

Hybrid Inverters

Hybrid inverter

Features

  •  Most advanced technology 
  • Multiple MPPT inputs
  • Provides backup power

The modern Hybrid inverter has improved over the years making it the  most cost effective , the panels are wired in a series, simply put all the panels are  connected together and is then connected into the component .

It’s a standalone unit that is installed close to your fuse box and meter, most modern Hybrid inverters are quieter due to having small or no fans making them perfect if you are to install inside the home.

If you have an unshaded roof that gets 100% of the sun spread evenly and you have no shade from a chimney or tree the dual MPPT feature is perfect, but if there are obstructions it can cause it to be  less efficient .

Another factor is scaling, if your energy needs exceed your inverters output you will need to  purchase a bigger version  so scaling up can increase your overall solar inverter price. We suggest purchasing one with a higher capacity just in case you need it.

Pros

  • Efficient
  • Affordable
  • Blends AC/DC Energy
  • Long lasting (around 15 years)

Cons

  • More expensive

How do Hybrid Solar Inverters work?

Hybrid inverter diagram

 The Hybrid inverter really does 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 Fusion inverters are the ideal Hybrid inverters, we highly recommend these.

What Size Do I Need?

Different size inverters

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 potential .

If you have a Hybrid inverter you can split that loads into 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 Essential and Non-essential loads 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.

Off-Grid Inverters

Off-Grid Inverter

Features

  • Easy to install
  • Expandable
  •  Lowest solar inverter price 

A very  popular choice because of their price , compared to previous Off-Grid inverters they are far easier to install due to the fact you have everything in one box instead of separate components.

In previous years an Off-Grid inverter was simply a metal box that literally only had one function, that was to convert DC to AC, then. you would need other components like an MPPT (this allows you to connect to solar panels), a Charge Controller (that allows you to connect to batteries), a monitoring device, and a bunch of wiring to tie it all together. Now, you get all of this in one box!

You get  2 main types of Off-Grid inverters and these are Low-voltage and High-voltage , the difference between the two comes down to how many high voltage solar panels you can connect to the inverter, more detail on how that works in this guide.

Unlike the Grid-Tied of Hybrid 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.

Pros

  • Easy to install
  • Expandable and modular

Cons

  • Less reliable than a Hybrid
  • Lifespan isn’t that great (around 10 years)
  • Can be noisy

Solar Inverter Prices, How Much Do They Cost?

The cost of a solar inverter all comes down to brand, build quality, features, and size.

For commercial inverters that have a massive kW rating you will be paying over R50,000 upwards, whereas, for residential inverters that typically start from a 3kW rating to around 10kW you will be paying between R6,000 for a budget Off-Grid to R40,000 for a top of the range Hybrid inverter that would also come with a great warranty.

Whatever the choice it's always best to start where you can, saving you money in the long term and having the ability to re-jig your system as time goes on.

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. Fusion - Technology has been around for a long time, good quality Hybrid inverters
  2. Goodwe - this Hybrid brand is of great quality and a great price
  3. SMA - aesthetically great looking and compact, been around for a long time and best known for Grid-Tied
  4. KODAK - A Voltronic make with KODAK branding, been around for a while

Resources:

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

3 comments

  1. Anonymous

    Visitor Rating: 4 Stars

  2. Visitor Rating: 5 Stars

  3. Nikola Batev

    Good day,
    I would need some advice and pricing.
    In January i bought 16 365W solar panels, 3kVA RCT 48V Inverters x 3 and four Pylon-Tech U 2000 batteries.
    During the installation ALL three inverter did blow up – incorrect installation by some company from Brakpan – CHC Electrical. So – now I am looking for the new inverters. I wold like to go for 5kVA – two f them. I would need a quote from you and advice – which ones can I install, how many solar panels can they take and – most important – can I split the system in two – one 5kVA + 2 Pylon Tech batteries and join them…or would you advise something else.

    1. Hi

      Sorry to hear about the inverters blowing up, your choice of 5kVa inverters sounds like a better option but before suggesting anything what kind of appliances/machines are you running and what is the maximum kW’s are you dealing with?

      If you’re looking for high end inverters that handle large loads and spikes we suggest the Victron inverters, if however you are dealing with moderate loads and spikes we’d would suggest an inverter from our Hybrid range or for the lower end of the end we suggest the Kodak (Voltronic) range.

      Thankfully you have PylonTech which are a good brand with a decent compatibility range.

      Give us a call or email us to advise further.

  4. Anonymous

    Visitor Rating: 4 Stars

  5. Visitor Rating: 4 Stars

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