How to Choose an Inverter for Solar System?

If you have decided to meet your energy needs with solar energy, you must be wondering about a solar inverter.

It’s one of the most important devices that you need to pay attention to before buying.

Without further ado, let me tell you how you can choose the best inverter for your solar system.

How Do I Choose A Solar Inverter?

To choose a solar inverter you need to know the type of inverter, the needed power capacity, the voltage rating and Efficiency and reliability.

Now let’s go through each item and find out what are your requirements. So you can select the perfect inverter for you.

What type of inverter do I need?

There are three main types of inverters that can be used in a solar energy system:

• string inverters,
• microinverters, and
• central inverters.

each one of these has different properties. So you should know what are they first.

String inverters

String inverters are the most common type of inverter used in solar energy systems.

They are typically installed near the main electrical panel and are connected to the solar panels through a series of DC wires, or “strings.”

String inverters are suitable for larger solar panel arrays and are generally more cost-effective than other types of inverters.

In a household we goes with this version. Mostly 90% of you and me goes with this one.

Microinverters

Microinverters are small inverters that are installed on each individual solar panel.

They are more expensive than string inverters but offer several advantages, such as improved efficiency and the ability to optimize the performance of each solar panel independently.

Microinverters are a good choice for solar systems with shading issues or irregularly shaped arrays. However, these are rarely used in common household systems.

Central inverters

Central inverters are large, industrial-sized inverters that are used in large-scale solar energy systems, such as those found at utility-scale solar farms.

They are the most expensive type of inverter, but are highly efficient and reliable, making them a good choice for large-scale solar systems.

How Do I Calculate Inverter Power Size?

To calculate the power capacity for your inverter, you will need to consider total power of your system.

The power needs of your loads.

The power needs of your loads are typically measured in watts (W).

To calculate the power needs of your loads, You have to add up the wattage of each device that you want to power.

For example, if you want to power a fridge (300 W), a TV (100 W), and a few lights (50 W), your power needs would be 450 W.

Here’s a table of household devices with there power values for you calculations.

Then you must keep another 20% of the total as additional power to be in safe side.

That means, the inverter size we calculated in above example will change into 540 watt inverter.

Usually, these kind of exact value inverters are not available.

So we goes for the nearest larger value.

That means, 600 watt inverter or 800 watt inverter as our final.

Online Inverter Size Calculator

You need not calculate the size of your inverter all by yourself.

You can also use several online tools to help you with the same.

They will ask you for the inputs and directly tell you the power of the inverter you need.

This online inverter size calculator is a simple and easy one to try.

Selecting the correct Voltage rating for the Inverter

The voltage rating refers to the range of voltage that the inverter is capable of handling.

It is important to choose an inverter with a voltage rating that is appropriate for your specific solar system for better performance.

Actually this is kind of a trade off between efficiency and cost.

• Lower the voltage rating, efficiency is low and the cost is low too
• Higher the voltage rating, efficiency is higher and the cost is higher too

I can category three main types of voltage ratings for inverters:

1. Low voltage inverters are appropriate for small-scale solar systems that use 12 or 24 volt DC electricity. These inverters are less expensive and easier to install than other types of inverters, but they are not appropriate for big solar systems.
2. Medium voltage inverters are appropriate for medium-sized solar systems that use 48 or 60 volt DC electricity. These inverters are more expensive and sophisticated than low voltage inverters, but they produce more power and have higher efficiency.
3. High voltage inverters are appropriate for large-scale solar systems that utilise 72 or 96 volt DC electricity. These inverters are the most expensive and sophisticated, yet they provide the best efficiency and power production.

Efficiency, Reliability and Other Features of inverters

While size is a vital parameter when selecting an inverter, you should also make sure you choose the one with the best efficiency.

You can also look for add-ons and other features that different companies may offer.

Here I have added a table of famous and known brands and inverter models with average life time for you to start looking for.

Further, make sure your inverter can handle the weather like dust and light rain. Sometimes, some inverters seem great.

But people often forget to check if they can stand tough weather. Therefore, you should see if the electrical components are well protected.

Also, you must check if your inverter has a working cooling system in place.

One of the most common reasons why inverters fail is because their cooling systems do not work properly.

Moreover, you should always check for any manufacturing defects.

Conclusion

Choosing the right inverter for your solar energy system is not an easy task.

However, it can save you a lot of maintenance time if you do it right. Once you have decided on an inverter, be sure to ask for a warranty.

This will help you get a replacement without any hassles, in case there is an issue.

Matthew Joseph Nandirio

Eng. Matthew Joseph Nandirio is the Founder of walkingsolar.
After graduating from the University of Houston in 2002, matt started working as a Solar Electrical Engineer for several multi-national solar energy companies.
He has a wide range of experiences including solar system requirement analysis, planning, maintaining, debugging and even solar device development through research.
He now shares his 20 years of expertise through his articles on the walkingsolar website.
Further, he is also the author of two books on Solar Technology, “Solar Power for Villages” and “DIY Solar System for Dummies”.