Solar inverters - types and principle of operation
With the growing popularity of renewable energy sources around the world, interest in solar systems is also growing rapidly. The ability of the photovoltaic installation to power an entire household is a huge environmental plus and a wonderful opportunity to use an inexhaustible natural resource to produce electricity.
When it comes to different types of solar systems, there are often questions about the components that make them up and the principle on which they work. Generally speaking, they consist of solar modules (or photovoltaic (PV) panels), a solar inverter, a metal structure and a cable. They can also contain a battery and an electricity meter, depending on the type of system and the number and type of panels is determined individually and depends on its power.
What is a solar inverter and how it works
In practice, solar panels are made of a combination of semiconductor layers, most often composed of crystalline silicon or gallium arsenide with positive and negative charge. When the sun heats them, the semiconductor layers absorb light and send energy to the photovoltaic cell. This energy stimulates the release of electrons which begin to move between the positive and negative layers, producing an electric current known as direct current (DC). Once this energy is produced it is either stored in a battery for later use or sent directly to an inverter (depending on the type of solar system).
The solar inverter is one of the most important components in this system. Its role is to convert the electricity generated by solar panels into usable energy to serve the needs of your home or workplace. Since all appliances operate on AC and not DC produced by the panels, the inverter is responsible for converting DC to AC output.
Advantages and disadvantages of solar inverters
This main component of any photovoltaic system is characterised by both specific advantages and disadvantages. To make the best choice it would be wise and appropriate to familiarise yourself with both the pros and cons of this device.
Advantages of the solar inverter
- The use of solar energy reduces the carbon footprint
- By using solar installations, you save money by significantly reducing your electricity bills
- Inverters and solar systems enable small businesses to reduce their electricity costs by meeting their energy needs
- The inverter is much easier to install and set up compared to generators
- Maintenance is easy and not much time consuming
Disadvantages of the solar inverter
- More reliable brands of inverters are expensive and not affordable for every investor
- Strong sunshine is needed to generate and transform sufficient electricity
- Additional installation space is required, especially for more powerful devices
- For optimal results a battery is required to operate at night to provide sufficient electricity for the home/business.
Basic types of solar inverters
- Standard string inverters
String solar inverters are the most common and preferred option for home installations. Usually only one string inverter is installed on a solar installation. It is characterised by the fact that the electricity generated by photovoltaic cells is currently consumed or transmitted directly to the grid. They are also known as grid inverters and are divided into 2 main subtypes: single-string (connected to only one string / group of photovoltaic panels) and multi-string (connected to two or more string solar modules).
- Battery inverters
They are used in cases when you prefer to have a separate inverter for the battery in your solar system. Their role is to convert the DC voltage accumulated in the batteries into AC. Thus, they allow the electricity stored in them to be used to power household appliances.
- Central inverters
They are huge and are mostly used for large-scale solar installations, solar parks and large photovoltaic facilities with a capacity of hundreds of kilowatts or megawatts. They are not intended for residential use and look like a large metal cabinet, and a central inverter could convert power up to 500 kW. Easy installation, solid construction and high productivity are their main advantages.
- Autonomous solar inverters
This type of inverters are suitable for locations and sites that are not supplied with electricity. They are extremely popular and are applied in places with insufficient or missing electricity. During the light part of the day this type of converter provides electricity from solar panels and the excess is stored in batteries. After the sun sets, the system goes into battery mode where stored electricity can be used. Thus, stand-alone solar inverters provide unlimited power and uninterrupted access to electricity everywhere.
- Hybrid inverters
They operate on a combined principle between mains and stand-alone inverters. They convert constant electricity into a variable that you can use at home. But not only that! The hybrid inverter could charge your solar battery from both the mains and the solar modules and transfer the excess energy produced to the grid for sale. Hybrid inverters are so named because they combine several devices.
As their name suggests microinverters are designed for smaller solar installations. Their main advantage is that they optimize each panel individually which contributes to their greater efficiency, even in shady conditions. In most cases the ratio of the solar panel to the microinverters is 1:1. Thus, each solar module or pair of modules has its own microinverter which is optimally compatible with its specifications and features.