Types Of Inverters For Solar Panels

Home Types Of Inverters For Solar Panels
24/06/2022
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What is a Solar Inverter? 

A PV inverter or a solar inverter is a kind of electrical converter. It converts the variable DC or directs the current output of a PV solar panel to a utility frequency AC or alternating current, which is used by an off-grid electrical network or commercial electrical grid. It’s a very important BOS or balance system in a photovoltaic system that allows AC-powered equipment. A solar inverter transfers the energy output derived from the solar panels to a usable form of electricity, which can be used commercially. This is how a solar inverter works.

How does a solar inverter work?

There are numerous inverters used in solar panels. The solar inverter takes the variable direct current from the solar panels and changes it to an alternating current. Generally, all the home appliances work on AC (Alternating Current) and not on DC (Direct Current), so the solar panels change the DC output that the solar panel collects. 

Let’s break down the working of the solar inverter for you. The sun falls on the solar panels or the photovoltaic cells made with semiconductor crystalline silicon layers. These layers are made of positive and negative layers connected via a junction. The function of these layers is to absorb the light that falls on them and then transfer this solar energy to what is called the photovoltaic cells. The solar energy then runs around and makes the electrons lose. These electrons travel between the positive and negative layers, which generate an electric current. This electric current is known as direct current.

After the energy is generated, one of the following things happens:

  • The energy generated is sent to the inverter directly or,
  • The energy generated is stored in the battery that can be used in the future. 
  • Where the energy transfers depend on the kind of inverter system installed.

After the energy is transferred to the inverter, it is generally in the DC format. But for commercial purposes, AC or alternate current is required. The energy in the inverter then passes through the transformer, which gives us an alternate current. We hope now you know what is a solar inverter and how it works. In a nutshell, the solar inverter converts the direct current with the help of one or multiple transistors.

Different Types of Inverters for PV Systems

The idea of installing solar inverters is like giving yourself and the environment a favor in many ways. You can choose from the various types of inverters, as per your needs or requirements. 

Straight String Inverter

String inverters are also called central inverters. These are the most common and oldest solar inverters in use. The straight string inverter is connected with a string of solar panels, and then they convert the DC input into AC.

The string inverters are reliable since they are one of the oldest solar inverters on the market. They are also the cheapest in the market.

For easy access for the monitoring, replacing, or repair of the inverter, the string inverters are located centrally near the side of the ground mount or on the side of the house.

The string inverters are less efficient compared to others because the inverters are connected to the entire string of the solar panels. If the shade is hiding even a single panel, the power output of the whole string will be cut off.

The string inverters only offer system-wide monitoring, while other solar inverters offer panel-to-panel monitoring, which is a big disadvantage while diagnosing the solar production and could be unfortunate for homeowners with solar panels who desire a high-level monitoring system.

Advantages

  • Multiple string inverters may be put on a project at a reasonable price, and if one fails, it’s simple to replace it with a new one. Because there aren’t many moving components, maintenance is straightforward. 
  • String inverter configurations may benefit from appropriate accessories like combiner boxes
  • Strings may be fused in a combiner box, decreasing the strings required for panel-to-panel connections.

Optimized String Inverter

There are power optimizers located at the backside of each panel, and they work in a coexistence manner with the string inverter. They do it by conditioning the DC from each panel and then sending it to the string inverter to convert it into AC.

This feature can reduce the impact of shading since the power optimizers condition the DC produced by an individual panel. This means that if one of the panels is partially shaded, then the whole grid won’t get affected, which would get affected otherwise.

Suppose you have power optimizers in your panels. In that case, you can benefit from panel-level monitoring and system-level monitoring thanks to the string inverter, which means that any issue can be monitored easily since each panel is being monitored.

The power optimizers are costlier than just the string inverter, but they are cheaper than microinverters.

If you want to upgrade your solar panel system in the future, you will require additional power optimizers and additional string inverters.

Note: If power optimizers have any issues and need repairs, it would not be easy to repair or replace them since they are located on the roof.

Advantages

  • You may construct your array in a partly shaded section or divide strings throughout your roof’s usable space. 
  • Optimizers guarantee that each panel in your system produces the highest output.
  • Optimizers provide individual panel monitoring.
  • You’ll be able to follow the creation of each panel, which will allow you to identify faults and shading problems panel by panel.

Micro-Inverter

The microinverters are the latest in the market, and they work by converting DC into AC directly. No string inverter is required at the back of each solar panel since the current is rectified on the spot.

The system is minimally impacted by sharing since the current is changed on each panel. If the shade is covering a panel partially, then only that panel will produce less power output leaving the whole system unaffected.

If you wish to expand your system in the future, you have to install a microinverter at the back of your panel.

The microinverters also offer panel-wise monitoring of the system just like the power optimizers, which allows issues in each panel to be diagnosed quickly and easily.

Microinverters are the most costly option in the solar inverter range. However, the benefits of the microinverters can outweigh the cost in some situations, for example, the shading issue.

Since the microinverter is installed at the back of the solar panel, it is more difficult to replace or repair them.

Advantages

  • Each panel and micro-inverter combination functions as a self-contained solar electric system.
  • Micro-inverter systems may be as small or as big as you need them, and panels can be created in any shape or orientation.
  • Micro-inverters separate each panel’s output and allow for panel-level monitoring.
  • You have the option of starting with a small-scale system that fits your budget and then scaling it later.

Hybrid Inverter

Lastly, we have a hybrid inverter on our list. As its name suggests, a hybrid solar inverter is a combination of a battery inverter and a solar inverter. It is one single piece of equipment that can smartly manage power from solar batteries, solar panels, and utility grids simultaneously.

From the above discussion, it is already known that the traditional inverter works to convert DC or direct current electricity that is produced by PV or photovoltaic systems to AC or alternating current. It is an alternating current that is responsible for powering the house. It also allows the transfer of electricity generation to the utility grid.

A battery inverter converts the DC electricity stored in the solar battery storage into AC electricity. 

These functions are combined into one device, known as a hybrid inverter. It improves the operations of the traditional solar inverter.

Advantages

  • It aids in the storage of surplus solar energy.
  • This stored solar energy may be utilized in the evening. This procedure is called Self-use or load shifting.
  • Power backup is always included with hybrid inverters.
  • Demand for conventional energy sources is being reduced.
  • There’s also a peak shaving option.

What to consider before choosing a solar inverter?

When buying a solar inverter, you will find plenty of options. There are several types of inverters used in the PV system. That said, the market is flooded with options, and you need to choose the best available choice. There is no denying that pricing is a critical factor in buying just anything; besides the cost, there are other critical considerations. 

Keep in mind that the load requirement is crucial, and the cost is directly proportional to the load handling capacity of the inverter. Furthermore, the technology and the kind of inverter are other factors that you should consider. With no further explanations, let us dive straight into the factors based on which you should choose an inverter. 

A micro-inverter
Source: Beny

Cost

Cost is a major factor that comes into consideration every time, but you should know that solar inverters are not cheap. If you are buying for your home or office, you will need a reasonable budget to buy a good option. Though, consider it a one-time investment. If you buy a high-quality option that comes with a steep price tag, you will save a good amount of money. 

Solar inverters with a good star rating have high price tags, but it helps save a good amount on electricity bills. You will have to pay the maintenance charges annually with solar inverters. They are minimal and are otherwise paid for by the traditional systems. Hence, if you want to save on the repairs and maintenance of the solar inverters, be wise in picking the best one available. 

You can have a budget, but a constrained budget may get you the wrong choice. Even if you may have to spend more, do it, thinking about the future. 

Rules & Regulations

The inverter helps transform solar energy into electricity, which can be used for your home or office. Hence, before investing in an inverter, solar panels will need to trap the energy. Carry out intense research for the products, grants, and suppliers to ensure that you have made the right choice. 

Based on the size of your space and the energy consumption, you will need an inverter to ensure that you make the best use of solar energy. Furthermore, know that the government offers a rebate on solar energy for the electricity of your space. Hence, you should know what rebate you are eligible for and how to receive it. 

The clean energy council also states that you should perform a few checks before buying solar products. Check if the installers are accredited and approved. You should always check for approvals before investing. 

You can either buy a system outright or finance it on your own. On the contrary, you can also choose to buy it through an alternative arrangement. The alternative purchasing options include a solar leasing agreement (SLA) or a solar power purchase agreement (SPLA). 

Residential or Commercial

Nowadays, people are increasingly looking to switch to solar options to obtain the maximum benefits. There are different kinds of options available for residential and commercial use. You need to decide the space you are buying the solar inverter. 

Commercial solar inverters are bigger than the residential options, and therefore, you should choose a bigger option for your workspace. Bigger options have better efficiency than the smaller ones, and so efficiency should be considered as well. The average rate of commercial options being more efficient than the residential options is 2% approx. 

The colors of commercial and residential solar inverters are different. The commercial options are mostly white, while residential options can be black or white. 

Load Requirement

The amount of load an inverter must manage determines its price since the more load an inverter must carry, the more powerful it must be. The greater an inverter’s VA (Volt Ampere), the more load it can manage; hence, its load-carrying capabilities highly influence its cost.

Depending on the number of appliances you wish to run off the auxiliary power, you may pay a little more or a little less depending on the load-carrying capabilities of your selected inverter.

Technology Used

The controller technology utilized in a solar inverter is another important consideration when determining the pricing of a solar inverter. Let’s look at the two technologies you have to choose from and how they vary.

PWM (Pulse Width Modulation)

These function similarly to a standard electric switch, allowing the solar array’s voltage to be kept close to the battery’s voltage[1]. When there is a voltage differential between the two, it operates by lowering the solar array’s voltage to match the battery’s. However, this is inefficient since it wastes energy by forcing a solar panel with a larger power-generating capacity to operate at lower voltages.

Maximum Power Point Tracking (MPPT) 

They vary from PWM kinds in that they guarantee that the solar arrays perform at their best while producing electricity. Unlike a PWM controller, it monitors the voltage in real-time. It regulates the output voltage to match the battery’s voltage without sacrificing efficiency, resulting in maximum power production and quicker battery charging.

Each sort of controller has its own set of benefits. The MPPT solar controllers are a little more costly and are suited for business organizations with high power demands. On the other hand, PWM controllers are appropriate for houses with low to medium power usage.

Inverter Types

We have various needs, and those requirements largely determine the sort of inverter we choose to suit those requirements. When opposed to someone searching for a modest power backup, someone wishing to live off-the-grid entirely will likely need to pay more.

Examining The Average Rating

Many dealers and buyers mistakenly associate a VA rating with a watt rating. A watt is the amount of energy extracted or provided by a piece of equipment, whereas a VA is the amount of energy gained by that piece of equipment. As a result, buyers should be aware of the VA rating idea. A normal VA rating of 706 VA to 940 VA should be sufficient to meet one’s basic power needs.

On the other hand, it’s critical to pay attention to the VA rating since if it’s lower than the power capacity you need, the inverter will trip due to overload.

Checking the certification is just as vital as the VA rating. These certifications certify that the solar inverter is both safe and compliant with the requirements established by top solar power companies.

IEC 62116-Anti-islanding, EC 62109-Safety, IEC 61683-Efficiency, IEC 60068-Environmental, EN 61000-EMC, and IEC 60529-Ingress protection are a few of the most relevant certifications. Some certification numbers and codes may be used to assess an inverter’s quality and capability before purchasing one.

Additional measures

Solar inverters have a long life in general. However, they must be serviced once a year to maintain optimal operation. To do so, only certified experts should inspect the inverter. The ideal situation would be for the same brand to supply services when needed and be ready to help.

It’s critical to check that the inverter’s voltage variation varies from 120V to 260V to guarantee that it maintains operating properly in voltage changes. It’s also vital to consider whether the inverter can handle the load when heavy equipment like a washing machine or an air conditioner is utilized. Apart from these features, the solar inverter must be safe, including short circuits, battery, and IP protection.

In the present situation, when regular load shedding occurs, and there is a lack of power, it is critical to consider long-term options. A decent solar panel inverter is one of the greatest alternatives available; thus, guaranteeing high quality is crucial in this scenario.

Key Takeaway

There are several inverters available for different spaces based on their requirements. If you are more interested in developing an energy-based home system, then you should choose to install a solar inverter. The choice of inverter plays a critical aspect, and you should be vigilant about the different available options. There are several different kinds available for people to choose from. Different pieces can be distinguished based on several factors, and you should consider them before deciding. 

Solar panels can convert direct current into alternating current with the help of an inverter. It can also help if you choose the right solar panel and inverter, which can help you save money on your electricity bill. People who want to buy a solar panel-inverter combo should think about these things first. A solar inverter is a considerable investment, and you should simplify things to make an ideal choice. 

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