The benefits of solar energy cannot be denied. The United Kingdom expanded its total solar PV capacity to 14 GW by the end of the first quarter of 2021.

Are you also planning to switch to solar energy? You might have had discussions with potential vendors about solar inverters. A solar inverter is the lifeblood of a solar PV system. It is the device that enables sunlight to be converted into usable electricity.

Solar panels generate direct current (DC) electricity while our homes run on alternating current (AC) electricity. A solar inverter is required to convert the DC power into AC power.

So, how should you pick the perfect solar power inverter for your solar power system? In this article, we will look at the different kinds of solar inverters and how to go about selecting them.

Grid-Tied Solar Inverters

A grid-tied inverter system converts DC voltage from the solar array into AC voltage. This power can either be used immediately or exported to the utility grid.

Grid-tied inverters are highly efficient, and installing them is a straightforward process. However, a grid inverter only works when the utility is on.

Most grid-tied inverters work on the Maximum Power Point Tracking (MPPT) technology. This feature milks the maximum amount of power possible from the solar PV array.

If you have a direct connection, the AC power produced by the solar panel system is sent to the utility grid. Conversely, if your connection is through the building’s grid, the AC power is consumed by your appliances first, and then the remainder is sent to the utility grid.

String Inverter

Solar Power System with InverterString inverters, or central inverters, treat the solar array as a single solar panel. They are quite popular to the credit of their cost-effectiveness and ease of installation.

The primary concern with string inverters is that even if one of the array’s panels is hampered, either by shade or degradation, the entire array’s performance is impacted. Consequently, the inverter’s DC input power reduces, thereby reducing the AC power.

Solar Micro Inverter

Solar micro-inverters, or module inverters, have a comparatively low output power, which is typically less than 250 W. These inverters are a part of the solar system and function as a central inverter exclusively for the solar panel that they are connected to.

Micro-inverters are installed on every panel of the array, and therefore the overall cost is usually high. However, this arrangement resolves the drawbacks of string inverters, as the malfunctioning of one panel does not disrupt the entire solar power system.

A micro inverter also uses MPPT to monitor the performance of solar panels and ensure that it squeezes maximum power from the panels.

Micro Parallel Inverter

Micro parallel inverters are a relatively new technology that combines the positives of both string inverters and micro-inverters.

This inverter is essentially a smart device consisting of four distinct channels connected to four different solar panels. Each of these channels works as a micro-inverter and can track the performance of its solar panel using MPPT.

The micro parallel inverter also acts as a string inverter for the four solar panels. However, if one panel fails, the other will not have to suffer.

Off-Grid Solar Inverters

Off-grid systems allow you to live and work wherever you want since you can generate your own electricity and live independently. The primary function of an off-grid inverter is to convert the output voltage of the solar array or the battery bank to AC voltage.

Not every off-grid solar system requires an inverter. If only DC loads have to be powered, off-grid inverters are not needed.

An off-grid inverter can either be directly connected to the solar array and provide AC electricity to the AC loads or connected to a backup inverter connected to battery storage directly or via a DC breaker.

Selecting A Solar Inverter

Picky a solar inverter can be very tricky since the markets are flooded with so many options.

We have curated a cheat sheet to help you find the best inverter for your needs.

For Off-Grid Solar Inverters

These inverters have many specifications that you need to consider before making a choice.

Let us discuss some of the key factors that you need to look at.

Output Voltage And Frequency

It is based on your load requirements and is typically the same as the standard supply voltage and frequency across the country.

Output Power

The power capacity of an off-grid inverter should be about 110 to 120% of your load’s total power capacity.

You can calculate the load’s total power capacity by adding power consumption of all your loads, considering the inductive loads with surge current, and oversizing to avoid underestimation.

Built-In Solar Charge Controller

The built-in solar charge controller can either be MPPT or PWM (pulse width modulation).

Technically, MPPT is better since it can convert solar panels’ high voltage to lower voltage, so it charges batteries with low losses and high efficiency. However, it costs much more than the PMW type.

If you can size your PMW solar charge controller according to the specs of your solar panel, it will work just as well as MPPT.

Solar Array Maximum Output

The maximum DC output voltage of the OV system should not be greater than the maximum DC input voltage of the inverter.

Battery Charger Output

Several off-grid solar inverters include battery chargers that are used to recharge batteries along with a backup generator. Ideally, the charger should be in the range of 50 to 100 amps DC.

Efficiency

Efficiency measures how much power your inverter delivers to your home from the batteries under perfect conditions. A peak efficiency rating should ideally be between 94% to 96%.

For Grid-Tied Solar Panels

If you are looking for a grid-tied inverter, keep the following factors in mind.

  • The minimum voltage of the solar array should be lower than the maximum input voltage (DC) of the inverter.
  • The PV array’s working voltage range should be within the MPPT voltage range of the inverter.
  • The inverter’s output power should be 0.9 to 0.95 of the solar array’s peak power.
  • The inverter’s minimum allowable system voltage should be lower than the PV array’s minimum DC voltage.
  • The PV array’s maximum current should be lesser than the maximum input DC.

Hybrid Solar Inverters

A hybrid solar inverter brings together the features of a standard solar inverter and a battery inverter. It is an affordable device with a smart charging electricity routing unit.

Home Solar Panel SystemHybrid systems consist of more inputs and outputs as opposed to a traditional string inverter. They simplify the process of moving electricity between your fuse box, the gird, and your energy storage unit.

Let us look at the various pros and cons of solar hybrid inverters.

Advantages Of A Solar Hybrid Inverter

  • These inverters integrate charge controlling, performance monitoring, and bi-directional inverter functions within an affordable package.
  • They come with built-in charge controllers that detect the best time to send electricity from your battery bank to the grid.
  • Many such inverters allow you to send your system performance data to a cloud portal by the company for monitoring and control.
  • DC-coupled hybrid inverters take DC power from the solar panels and feed it directly to your battery bank without converting it to AC power.
  • Some inverters enable you to connect a smaller inverter with your solar array or a larger array to your solar inverter.

Disadvantages Of A Solar Hybrid Inverter

  • Some inverters may not have the feature to use the electricity generated from your panels when the grid is down.
  • Higher performance hybrid inverters are typically designed for indoor installations and may not be IP65 rated, which means they are not weather resistant.
  • If you already own a working solar panel system and want to add battery resilience, hybrid inverters may not be the best choice for your solar systems.

Types Of Solar Inverters Based On The Output Wave

Solar inverters can be classified into three categories based on the type of output wave produced.

Pure Sine Wave Inverter

Pure sine wave inverters are pretty expensive devices since they produce AC power similar to actual sine waves provided by the grid. A pure sine wave is steady, continuous, and provides a periodic and smooth oscillation.

These inverters have the highest functionality, given that they can run any equipment that is designed to work on a pure sine wave.

The following devices will work exclusively on a pure sine wave inverter. They might get damaged if you try to run them on other inverters.

  • AC devices such as compressors, microwaves, or refrigerators.
  • Audio and video equipment
  • Certain medical equipment
  • Satellite systems

If you are thinking about installing solar panels on your roof or RV, you should explore this option. Pure sine wave inverters not only convert DC to AC but also bring the voltage up to the grid level.

Square Wave Inverter

Solar Panels on RoofSquare wave inverters, or modified sine wave inverters, are perhaps the simplest kinds of inverters. They are suited to run simple tools and equipment with universal motors, but nothing beyond that.

Such inverters are also known as digital inverters and generate square wave AC output. Nowadays, a modified sine wave inverter is not as common.

You can only find old or cheap versions. Square wave inverters produce very loud noises and are not entirely reliable, so it does not come as a surprise that their popularity has declined.

Quasi Sine Wave Inverter

Quasi sine wave inverters, also known as stepped sine wave inverters, are not easily accessible in the market. These inverters are low-cost solutions for running electronic gadgets such as computers.

Stepped sine wave inverters may also create additional noise, like square inverters. Moreover, they are not suited for devices such as microwave ovens, vacuum cleaners, mobile phones, computers, etc.

Endnotes

Understanding solar panel inverters is not an easy task. There is a lot of technology that you will have to familiarize yourself with.

When you buy a solar inverter, it is not just about deciding whether you want to get an off-grid system, be tied to the grid, or adopt a hybrid model. You also have to look at the other details discussed above.

Regardless of the time and effort involved in zeroing in on a solar inverter, the process is entirely worth it. Switching to solar electricity not only lowers your electricity bills but is also great for the environment.