Solar Inverter

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Categories: Advice, Inverters, Solar Power

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

After you read this definitive guide you will understand:

What Is A Solar Inverter

Pure sine inverter
A Pure Sine Inverter

An Inverter  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 Solar Inverters Work

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

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

Grid-Tied / Hybrid Inverters

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

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

Here are the general functions that a Grid-Tied / Hybrid Inverter 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:

String Inverters

String Solar Inverter

Features

  •  Lowest solar inverter price 
  • Multiple MPPT inputs
  • Provides backup power

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

It’s a standalone box that is installed close to your fuse box and meter, the newer versions don’t tend to make much or any noise compared to older ones.

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 string inverter is perfect, but if there are obstructions it can cause the inverter to be  less efficient .

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

Pros

  • Efficient
  • Affordable
  • Long lasting (around 15 years)

Cons

  • Not efficient if panel/s are shaded
  • Expanding is difficult

Micro-Inverters

Micro Inverter

Features

  • Easy to install
  • Expandable
  • Maximises output of each panel

These small inverters are connected to the solar panel itself, they are easy and safe to install.  They can produce up to 25% more energy maximising the solar panel output .

 Ideal for expanding  the Micro-Inverter monitors (module-level monitoring) each panel independently making them  operate independently , they are the better option when dealing with rooftops that have different pitches and partly shaded.

 Because each panel is independent it maximises each panel  which means if there is a shaded or low-efficient panel it won’t hinder the rest of the group of panels (solar array) as the string inverter does.

The downsides to these variations are the solar inverter price, although they have come down they are the more expensive route.

Pros

  • Easy to install
  • Long lasting (25-year warranties)
  • Expandable and modular

Cons

  • More expensive
  • Maintenance requires rooftop access
  • Exposure to the elements can cause issues (extreme cases)

Solar Optimisers

SolarEdge Solar Optimiser Cell

Although not a Solar Inverter, the Solar Optimiser works with a String Inverter and  performs much like the Micro-inverter  by maximising the output of the Solar Panel.

Features

  •  Works with String Inverters 
  • Performs in the same way as a Micro-inverter
  • Affordable

These components are perfect if you already have a String Inverter or if you know which Solar Panels are shaded or pitched differently.  They are connected to the panel itself much like the Micro-inverter .

Pros

  • Easy to install
  •  Long lasting (25-year warranties) 
  • Expandable and modular

Cons

  • Maintenance requires rooftop access
  • Exposure to the elements can cause issues (extreme cases)

Off-Grid Inverters

Unlike the Grid-Tied Inverter options, an Off-Grid inverter requires batteries, the power from the Solar 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 inverters available:

Pure Sine wave

Pure sine inverter

Features

  •  Delivers quality power output 
  • Quieter than Modified Sine wave
  • Ideal for modern appliances

A safer option the Pure Sine inverter is the main choice for Off-Grid, affordable and deliver higher quality output. Almost all appliances will work with these inverters making them highly compatible with most systems.

Modified Sine wave

Modified Sine Wave Inverter

Features

  • Lower solar inverter price

These inverters output lower quality power and are only compatible with certain appliances. They can be problematic for electronic equipment,  we recommend Sine wave inverters .

How much Output do You 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 inverter, 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 .

Once again, don’t let the price dominate your decision. It’s important to stick to your budget, but investing in a low-quality inverter means having it for a shorter period of time.

 Always keep in mind that the inverter has to do a heavy-duty job, and it’s the key to transforming the DC current. 

Solar Inverter Prices

Grid-Tied Inverters

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

Single Phase Grid-Tied Options

3 Phase Grid-Tied Options

Hybrid Inverters

Micro Inverters / Power Optimisers

SolarAdvice Rating
Overall
4.7
  • Return on Investment
  • Affordability
  • Energy Saving
  • Overall Cost
  • Installation (Speed)
  • Installation (Cost)

Solar Inverter Review Summary

Depending on what type of inverter you choose the experience can differ greatly, for such an important component it’s safe to say that we rate the Solar Inverter high.

Inverters have improved over the years and they’re only getting more reliable, cheaper, easier to install with improved monitoring features.

Consult with a technician before purchasing your inverter just to make sure it suits your needs.

Pros

Enables system monitoring

Affordable

Expandable (Micro-inverters)

Long lasting

Cons

Expensive for larger systems

Can vary depending on manufacter

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