How to Choose The Right Solar Inverter

A solar inverter is a component of photovoltaic solar systems that is responsible for converting direct current (energy produced by solar panels) into alternating current (electricity that we can use) so that we can generate and consume our own electricity.

How to Choose The Right Solar Inverter

How do inverters for solar panels work?

When we think of a photovoltaic self-consumption installation, it is convenient to pay attention to all the components of the solar installation. However, in the case of inverters, it is especially important since the current converter is responsible for making use of the energy generated by the solar panel.

When photovoltaic panels receive light, a direct current is produced thanks to the movement of electrons present in the photovoltaic cells of a solar panel, the role of the solar inverter by converting electricity into alternating current begins.

In this way, once converted, we can use the washing machine, oven, electronic devices, etc. In addition, if we generate more electricity than we consume, we can accumulate it in solar batteries or pour it into the grid.

In addition to their main function, they are also responsible for:

  • Make it easier for installers and owners to supervise the proper functioning of their installation. In case there is an anomaly, they are able to stop the production of energy, thus avoiding any risk associated with an electrical problem.
  • Provide information about the diagnosis of equipment for early troubleshooting.
  • They optimize the overall performance of the installation since they allow to obtain the maximum energy use of each of the photovoltaic solar panels.

What types of photovoltaic inverters are there?

When classifying the types of inverters, we must first differentiate them according to the type of installation of solar panels: grid connection or isolated.

Grid connection inverters

This group is made up of those that transform the energy generated by solar panels into electricity for consumption in homes and/or businesses and that need to be synchronized with the general electricity grid.

In addition to converting direct current into alternating current, they are also responsible for maintaining the energy voltage generated by the plates a little higher than that of the grid. In this way, the use of solar energy is put first, saving as much as possible thanks to self-consumption.

Grid connection inverters are not right for isolated installations.

The main function of the inverters is to convert the current; however, depending on their technology, they will have some functionalities or others. There are mainly two types of solar inverters:

1. String

Also known as the centralized or “chain” inverter. This is the standard inverter; each panel is connected in series, and the energy produced is sent to a single inverter. Optimizers can improve performance in conditions where each board has a different production (with shadows).

Not all String inverters work with optimizers; you will have to make sure according to the manufacturer.

Pros:

  • They are the most economical
  • They are the most used
  • Easy maintenance
  • Easy to find and use

Cons:

  • There is a single inverter in the chain; it is not recommended for installations with many shadows and does not allow large extensions of the installation in the future.

2. Microinverter

This inverter is known as the distributed inverter since, unlike the String (there is a single inverter), here one is located in each solar panel.

Pros:

  • The installation will continue to produce power even if one or two system boards have lower performance.
  • They allow you to review the performance of specific boards, making it much easier to detect problems.
  • Panels don’t have to have the same orientation.
  • It allows you to expand the installation in a very simple way.

Cons:

  • More expensive than the previous ones.
  • More expensive maintenance.
  • More heat losses than Strings.
  • For large facilities, you have to put several.

Once we understand the functionality and the various types of inverters, the next step is to decide which one suits you for your self-consumption installation. The choice will depend on your type of installation:

String: Standard installations without shadows or shadows are very punctual during the day.

Microinverters: If you plan to increase the installation in the future.

Optimizers: If your installation has many requirements and/or shadows.

 

Inverters for isolated photovoltaic systems

These types of inverters are used in installations without connection to the electricity grid. The use of batteries is necessary for all of them. They are ideal for solar systems in motorhomes, boats, cottages, etc. Within this group, we find:

1. Isolated

They transform the current of the batteries to 220V in order to power the appliances. This type is programmed to stop the supply when the voltage is too low and thus avoid over discharges.

2. Inverter-charger

This type of inverter is characterized by having, in addition to the inverter for isolated installations, a charger that is activated when the voltage of the batteries is very low. In this way, you will be able to provide the necessary energy again to the batteries for the supply in the house. 

Among its advantages, we do not depend entirely on solar energy to have batteries, and it also supplies energy at the same time that the batteries are charged.

By having a charger, the batteries can be charged when needed (for example: on rainy days). Therefore, as it does not depend entirely on solar energy, it is not necessary to design the installation to cover the energy needs in specific cases by reducing the number of plates and the capacity of the battery, which entails significant economic savings for the installation.

3. Hybrid inverters

This type of inverter includes those that allow the capture of energy from both the electricity grid and solar batteries. They are very versatile for photovoltaic installations in homes. Ideal for those homes to which the energy network reaches scarcely since it takes full advantage of all the resources of your installation. In short, it is an “all-in-one” equipment: inverter, solar regulator, and charger.

 

What should be the location of the current inverter? And its size?

The inverter must be placed in a place that can be accessed without problems and that, at the same time, is not within reach of those who could face risks, such as young children. In addition, it should be placed near solar panels and in well-ventilated places. It should not be placed next to places where heat accumulates and/or receive sunlight directly since this type of device usually suffers heating.

On the other hand, another series of factors must be taken into account, such as the noise that can be produced in operation, so it is not convenient to locate it near the living room or the bedroom of the tenants since it can disturb their rest.

The vast majority of inverters have hardly any noise. However, I recommend asking the manufacturer to ensure that it will not interrupt your rest.

The size of the inverter will depend on the power to fit your photovoltaic system. It is not a simple issue but essential, since if you choose one with lower power, you will not have enough energy to meet your needs.

If you choose an inverter with power much higher than that of your solar panels, you will not get the maximum performance from your photovoltaic installation. On the contrary, if you choose one with a much higher power, it may not start. The inverters have an optimal operating range that depends on the number of solar panels installed. When in doubt, it is always more convenient to choose a slightly inferior one. For example, if the power of your installation is 3.2 kW, we recommend that you preferably opt for a 3 kW one than a 4 kW one.

Pure or modified sine wave inverter?

In addition to the classification of inverters according to the type of installation (connected to the grid or isolated), it is essential to know that there are two types depending on their type of wave:

  • Pure sine wave: this type of inverter is suitable for any type of appliance; they are designed to be used in isolated installations without causing interference since they reproduce a uniform wave between different pulses.
  • Modified wave: they are valid for electronic devices that do not have a motor since they do not work well with complex devices (washing machines, drills, etc.). Unlike the previous ones, these produce more abrupt and segmented waves.

When using pure sine wave inverters, the type of current you feed electronics with is always the same. We recommend using this type of inverter because otherwise, the life of the devices will be reduced.

What are rated power and peak power in an installation?

In the process of choosing the inverter, we must also know these concepts: The peak power is the amount of kW installed, and the nominal photovoltaic power is the power of the inverter, that is, the transformed energy suitable for consumption. The nominal power is the one that marks the limit since it is not possible to produce more energy than the inverter is able to convert. However, installations usually have a higher peak power in order to fully cover the capacity of the inverter, improve the performance of the installation and make it feasible to meet energy needs.

Therefore, rated power and peak power must go hand in hand. An installation with a lot of peak power and very low-rated power will be limited by the inverter; otherwise, the investor will not start.

Which investor to choose? Prices, brands, and stores

The price of inverters for photovoltaic panels ranges from $400 – $1500 for residential to $3,000 or much more for companies and solar farms. It will depend on the power, type, and quality of it.

It is very important that you choose your investor taking into account the characteristics of your project and analyzing the different alternatives. If you need help, contact our team of energy experts who will be happy to help you choose the option that best suits your home.

Points to keep in mind when choosing the right investor

  • Although they are reliable, repairing breakdowns is usually not cheap.
  • Choose those that offer high performance.
  • If you plan to expand your installation in the future, you must connect another additional inverter in parallel or perform the installation from the beginning with micro-inverters in such a way that the available power can be expanded.