Which solar inverter to choose for your solar panel installation?

In this article I will show you which solar inverter to choose for your solar panel installation. If you are thinking of installing solar panels in your home you should know that the photovoltaic installation must have a solar inverter, this is the device that transforms the direct current produced by the solar panels into alternating energy that is the one we use at home.

Which solar inverter to choose for your solar panel installation?

We help you with the technical specifications to choose an inverter knowing what you buy

One of the key decisions when  installing solar panels  on your roof is the type of inverter you are going to use. The solar inverter or photovoltaic inverter is one of the most important elements of a self-consumption installation, and, surely, the most unknown.

A solar inverter is a converter that  transforms the direct current  it receives from the photovoltaic panels into alternating current, which is what you can use in your home, store in batteries or feed into the network.

What types of solar inverters are there? 

In the case of  residential solar self-consumption, three types  of solar inverters  are mainly used  : string or chain inverters, microinverters and power optimizers . In the solar industry, microinverters and power optimizers are known as “Module Level Power Electronics” or MLPEs.

Nowadays, string inverters and those with power optimizers are the most widely used at a residential level throughout the world, capturing a high market share. However, microinverters are beginning to gain a foothold, as they have managed to reduce many manufacturing costs.

How do photovoltaic inverters work?

When our photovoltaic panels receive sunlight, the electrons begin to move inside the solar cells, which produces continuous electricity. The circuits inside the photovoltaic cells  collect that energy for us to use in our home or business.

This is where the solar inverter comes into play. Most homes use alternating current electricity, not direct current, so the energy produced by  solar panels  is not useful on its own. When the  solar panels  collect sunlight and convert it into power, it is sent to the inverter, which  receives the direct current electricity and converts it to alternating current .

That’s when solar electricity can power appliances and electronics. If we are producing more electricity than we need, we can also store it in batteries  or feed it into the electricity grid to receive financial compensation in return.

Main functions of the photovoltaic inverter

• Energy conversion:  The photovoltaic solar inverter converts direct current into alternating current, which is used by all our electrical appliances at home.
• Energy optimization:  Maximizes the energy generation of the solar panels. To do this, the panels are insulated individually in order to increase energy production, and therefore improve the overall performance of the installation.
• Monitoring and protection:  A solar inverter monitorsthe energy yields of the photovoltaic system, the electrical activity and the signals when a problem arises. This information can be viewed on the device itself or from another location if the appropriate communication technology and online services are implemented.
• Constant operation:  A photovoltaic installation is designed to provide energy outdoors and in all weather conditions. The PV inverter offers constant operation by dissipating heat in a consistent manner.
  

Which solar inverter to choose for your self-consumption installation with solar panels?

Surely you have doubts about what type of photovoltaic solar inverter is best for your home or company. They all have the same function, however, there are some differences between them.

String inverters (or chain)

String inverters are currently the most widely used option worldwide. If your home has a roof that is not affected by shadows and has a single direction, they are a good choice.

For example, if your home has a gabled roof, it will be a good solution if you only put  solar panels  on one of the skirts, but if you put them on both you will be facing a terrible solution.

Most small-scale solar power systems use a string inverter, also known as a “centralized” inverter. In a self-  consumption  installation with a string inverter,  each panel is connected in series . When they produce power, it is all sent to a single inverter, which is usually located on the side of the house, in the garage or in the basement. The inverter converts all the green energy generated by your solar panels into electricity that you can use in your home or business.

 

• Pros:  String inverters are the lowest cost option and are a proven technology. They are also easy to maintain, as they are located in easily accessible places.

 

• Cons:  If our system uses a string inverter, it will only produce as much useful electricity as the solar panel that produces the least. The generation of electricity in an installation with a string inverter can suffer from the “bottleneck” effect, or be drastically reduced, if only one or two of the panels are shaded or are not working properly.

 

• Ideal for:  Homes with “unobstructed” roofs that receive radiation consistently throughout the day, and for homeowners seeking photovoltaic systems at the lowest cost.

 

Operation of string inverters

Solar panels are connected in series with each other, and are grouped in  strands . Each branch is connected to a single solar inverter, which is responsible for converting the direct current coming from the panels into alternating current. The string inverter was developed decades ago, so it is a mature technology that has been tested and is effective, however, it is not suitable for certain types of installation.

Due to its operating principle, a string inverter captures  as much electricity as the least efficient panel on  the branch, that is, if a single panel on the branch is affected by a shadow at any time of the day or stationary, the entire power of the branch is reduced to the power of the panel located in the shaded area. As a consequence of this, the string inverter is not a good solution when your panels face several directions or are affected by shadows.

These  shadows  caused by surrounding objects are one of the main reasons why a panel significantly reduces, or even cancels, its production. Therefore, a good solution to avoid a shadow area on your roof is to remove the object that produces it or not install it in the shadow area.

Microinverters

Microinverters have  recently gained popularity in  residential   photovoltaic self -consumption. However, microinverters are usually more expensive than string inverters and power optimizers, but they do have certain advantages. Over time, the cost of microinverters continues to decrease, which directly affects the increase in sales.

 

If a string inverter can be considered as a “centralized” inverter, then microinverters are “distributed” inverters. In self-consumption installations with microinverters,  each solar panel has a small solar inverter  installed. Instead of sending power from all the panels to a single inverter, microinverter systems convert DC solar  power to AC power on the roof itself.

 

• Pros:   Microinverters are more efficient than string inverters. Solar panel installations that use this technology continue to produce energy even if one or two of the panels in the system have lower performance. They also allow you to monitor the performance of specific solar panels, which makes it easy to identify production problems if they occur.

 

• Cons:  Microinverters cost more than a string inverter, and are more difficult to maintain or repair in the event of a problem, since they are on the deck.

 

• Ideal For:  Homeowners who are willing to pay more to increase the efficiency of their solar panel system.

 

Operation of microinverters

Microinverters are installed on each solar panel  individually . Each one of them is an independent converter that transforms direct current into alternating current on site, without the need for direct current to travel to the center of investment as is the case with string inverters. The microinverters can be integrated directly into the solar panel or located next to it, in the metal structure.

The main advantage offered by microinverters over string inverters is the  elimination of the negative impact caused by shadows, whether total or partial. Consequently, production increases because the “bottleneck” effect produced in string inverters is eliminated. In addition, microinverters allow individual monitoring of each panel.

 

 

power optimizers

Power optimizers  combine the best  of string inverters and microinverters, but are slightly cheaper than microinverters. Like microinverters, power optimizers  are located on the deck   next to – or integrated with – individual solar panels. However, systems with power optimizers  still send power to a centralized inverter .

Power optimizers do not convert direct current electricity to alternating current at the solar panel site. Rather, they  “ condition”  DC electricity by  setting the voltage  of the electricity at the time it is sent to the  photovoltaic inverter . A  solar panel installation  with power optimizers is more efficient than one that only uses a string inverter.

 

• Pros:  They improve the efficiency of the installation, they offer the advantage of monitoring the performance of each solar panel individually, and they reduce the effect of shadows on the performance of the installation. Installations that use power optimizers are more economically affordable than microinverters and have lower maintenance costs.

 

• Cons:  An installation with power optimizers will cost more than an installation with a string inverter.

 

• Ideal for:  Homeowners who want to maximize the production of their solar panel installation and not worry about costly maintenance. Homes that have “complicated” roofs with gables, chimneys, or other objects that can cause shadows.

 

How power optimizers work

 

Like microinverters, power optimizers are devices attached to the rear of each solar panel, allowing it to operate  independently  of the rest of the modules in its row.

The main difference with microinverters is that power optimizers do not convert direct current into alternating current. They are direct current to direct current converters   whose function is to modify the operating point of the IV curve (Intensity-Voltage) of the panels that receive shadows, since the rest continue to function the same. In other words, the power optimizers follow the MPPT (maximum power point) with fixed V (fixed voltage) of each circuit, which allows unifying the currents of the branch connected to the string inverter.

 

Al igual que los microinversores, permiten la monitorización individual de cada panel solar reduciendo el efecto de las sombras en el funcionamiento de la instalación solar fotovoltaica. Las instalaciones que utilizan optimizadores son más asequibles económicamente y tienen unos costes menores de mantenimiento.

Resumen de conceptos clave

 

1. La función de los inversores solares es transformar la corriente continua, procedente del sistema fotovoltaico, en corriente alterna para uso doméstico.
2. Existen tres tipos de inversores solares: inversores string, microinversores, optimizadores de potencia.
3. Las tecnologías MLPEs (microinversores y optimizadores de potencia) son más caras porque tienen más equipamientos electrónicos.
4. Si alguna placa solar de la instalación fotovoltaica se ve afectado por sombras o la instalación se encuentra en varias direcciones (cubiertas complicadas), las tecnologías MLPEs son la mejor solución.
5. Los microinversores y los optimizadores de potencia permiten monitorizar la producción de cada panel de manera individual.
6. Los microinversores y los optimizadores de potencia permiten que tu instalación fotovoltaica tenga una producción ligeramente mayor.

 

Módulos inteligentes (Smart modules)

Cada vez más a menudo los fabricantes de optimizadores de potencia y de placas solares están empezando a colaborar en el desarrollo de módulos inteligentes. Son resultado de la integración de optimizadores de potencia o de microinversores en los paneles solares.

Los módulos inteligentes (smart modules) ofrecen varias ventajas como son: un proceso de instalación más simple y menores costes, ya que son necesarias un menor número de horas de instalación.

Compara antes de tomar una decisión. ¿Cómo elegir la mejor opción de inversor fotovoltaico?

 

Ahora que entendemos cómo funcionan los inversores solares fotovoltaicos, el siguiente paso es decidir qué tipo es mejor para nuestra instalación de autoconsumo eléctrico. Debes analizar todas las opciones, ya que no todos los inversores fotovoltaicos son buenas alternativas. Al final, la elección se reduce a cuánto estamos dispuestos a pagar por un rendimiento mayor, y si estamos dispuestos a costear un posible mantenimiento adicional.

 

At  SotySolar  we can help you make that decision about your solar inverter options. When registering your home, you will receive a personalized offer, and you will be able to evaluate the costs and benefits of the different solar inverter options. We will accompany you during the process, solving any questions that may arise. Start saving on your electricity bill now , producing your own green energy.