In this simple guide to solar inverters, we’ll cover the three basic questions most people have. These are:
- What does an inverter do?
- What types of solar inverters are there?
- Do you need an inverter for your solar system?
What does a solar inverter do?
Household appliances like your TV or fridge run on alternate current (AC).
The electricity supplied to your home by the power company is alternate current.
Solar panels produce direct current (DC). Batteries also store DC. Inverters convert the direct current from your solar panels or batteries into the alternate current your appliances use.
What is the "sine wave" of an inverter?
A sine wave or waveform is the quality of the current signal an inverter sends to an appliance.
You can think of it as the “broadcast frequency” of a current.
The sine wave is important because some appliances will not work properly with certain inverters because of their sine wave.
There are three types of waveforms. These are pure sine wave, modified sine wave, and square wave.
Pure sine wave vs modified sine wave vs square wave
Although it’s the most expensive, pure sine wave is the most recommended waveform for inverters.
This is because it closely matches the alternate current voltage from the grid.
This is critically important if you want to sell electricity back to the grid through net metering. Grid-tie inverters use a pure sine wave.
A modified sine wave is cheaper than a pure sine wave.
It does however produce a lower quality waveform that might affect how your appliances work (poor picture quality on your TV, for example).
Because it is a lower quality waveform, you might not be able to export electricity to the grid.
While they are cheaper than pure sine, square wave inverters are the least used in solar power systems.
This is because they produce a lower quality waveform that might not work with your appliances.
In most cases, pure sine wave inverters are the best option to use, especially if you’re looking to sell electricity from your solar power system.
Types of solar inverters
There are three main types of inverters. These are hybrid, off-grid and grid-tied.
Each of these can be pure sine, modified sine or square wave.
These are for a grid-tied solar system. Aside from converting DC to AC, grid-tied inverters also convert the voltage from your solar panels to match the voltage from your utility.
This is the feature that allows you to sell electricity to the grid.
The biggest drawback of a grid-tie inverter is that it does not work in the absence of power from the utility.
This means your solar system shuts down when there is load shedding or a power outage.
If the electricity is always on and you just want to reduce your electricity bill then this inverter will do just fine.
If you don’t have grid-supplied electricity or supply is erratic, then what you need is an off-grid or hybrid inverter.
An off-grid inverter is for a stand-alone or off-grid solar system.
Some off-grid inverters work as inverter/chargers because they also allow you to charge your battery bank from an AC source such as a generator.
These inverters are ideal for game lodges, rural areas, or new homes that are not connected to the grid.
Learn more about the difference between grid-tied and off-grid solar systems.
Hybrid inverters give you versatility because they can work in both a grid-tied and off-grid system.
Unlike grid-tied inverters, however, hybrids don’t shut down during load shedding or a blackout.
Rather, they disconnect from the grid and continue supplying you with power.
They also work as an inverter/charger because they can connect to the grid or a secondary AC source like a generator to charge the battery bank when the sun can’t do the job.
It’s this versatility that makes hybrids your best option if:
- You’re trying to beat load shedding or power outages and
- You want to sell your excess electricity to the grid
Solar inverter FAQs
These are some of the most common questions people have about inverters.
How much does a solar inverter cost?
This depends on the size of your system. For example, the price for a 5kV solar inverter in Zimbabwe starts from $750 to $2000.
Which is the best solar inverter for home use?
Hybrid inverters are the best option for both residential and commercial use because they will still work after the power has gone out.
Can solar panels work without an inverter?
Yes, a solar panel can work without an inverter. But this is only with appliances that use direct current.
Can an inverter work without a battery?
Hybrid inverters can work without batteries.
What size inverter do I need for solar panels?
Getting an inverter with a bigger power rating (up to 30%) than what you need is good practice.
This gives you flexibility should you need to expand your system in the future.
Another rule of thumb is your solar panel capacity should not be over 30% more than your inverter capacity.
Therefore, a 5kW inverter should have, at most, a 6.5kW solar array.
How long does an inverter last?
A good quality solar inverter lasts for 10 years. Some can go up to 15 years.
Let’s wrap up by going over the three main take aways from this post.
A solar inverter converts direct current to alternate current.
The three main types of inverters are off-grid, grid-tied and hybrid.
Hybrid inverters are the best choice for homes and business because they still provide electricity in a blackout or during load shedding.
Think you’re up to speed on solar? Test your knowledge by taking our 5 minute Solar 101 Quiz.