If you want to install panels on roof of your house or in your condominium and want to depend less and less on electricity grid, you need to know fundamental component of system well, solar inverter. Inverter, together with panels, production meter and any storage batteries, is an essential part of solar system because it makes solar energy usable.
For this reason, it is tool to be chosen with care: you need to consider how it works, in which system it should be placed, what power to choose. In this article you will find all information you need to select solar inverter that best suits your needs. In short, information you cannot miss:
- There are different types of inverters based ontype of connection with modules
- If you are looking for inverter for your storage system, hybrid inverter is one for you
- Power of inverter is directly linked to power of system
- Read more: How to Connect Solar Inverter Without Battery
Table of Contents
Solar inverter used for?
Solar inverter is part of system that converts energy coming from panels and makes it usable. This element, in energy flow, acts immediately after energy production by panels.
Energy it receives from modules is not usable, In fact Direct Current (DC), which cannot be used at home.
Inverter therefore transforms direct current into alternating current (AC), which is energy that powers electrical systems of homes.
In addition to having function of making energy produced by solar panels usable, inverter is also essential for other operations:
- As it transforms direct current into alternating current, it optimizes this energy, maximizing performance of modules
- Its safety devices protect entire system in case of failure
It can be placed inside or outside home depending on needs, but since it is an electrical appliance it is important that it is far from heat sources. As we will see, depending on type of inverter chosen there are different recommendations on its positioning.
Inverter has easily replaceable electronic components, so it generally has lifespan of around 10-12 years.
How Solar Panel Inverter Works
But how does single component convert energy produced by system? To understand inverter’s operation in more depth, you need to know that its work can be compared to that of an alternator and transformer:
- Alternator converts mechanical energy into an alternating electrical current
- Transformer, through use of coil in which alternating current flows, generates energy
Inverter has function of both mechanisms, which are then controlled and maximized by safety devices. Inverter is equipped with lights of different colors and different flashes, which indicate various operating states.
Meanings that colors and flashes assume vary from model to model, but they are essential to understand health status of the system. Once you have purchased inverter that is best for you, it will therefore be important to know how to read these signals as best as possible.
Single-phase and three-phase inverters of 3kW and 6kW
In terms of structure, system and operation, there are 2 types of solar inverters: single-phase and three-phase. Here is a summary:
SINGLE-PHASE INVERTER | THREE-PHASE INVERTER |
1 phase of alternating current | 3 phases of alternating current |
Power ≤ 6 kW | Power ≥ 3 kW |
Homes and small businesses | Large companies, industrial plants, but also homes and small businesses |
SINGLE-PHASE INVERTER
Single-phase inverter is component used in single-phase solar system, which uses single phase of alternating current and has maximum power of about 6 kW. We find inverter and single-phase network mainly in homes and small businesses, and they are used to power mostly household appliances or users with low voltage.
THREE-PHASE INVERTER
Three-phase inverter is composed of 3 phases and converts 3 different alternating currents. As its name suggests, it is part of three-phase electrical system, this is often present in large companies and industrial plants due to high power of energy it can generate. However, it is still possible to have three-phase inverter in your home, it can even reach power of 3kW.
Solar Inverter: connection types
Depending on type of connection to panels and solar strings, different types of inverters can be distinguished: string inverter, centralized inverter, micro inverter.
A solar string is set of solar panels all connected in series.
In table small summary of types of inverters and their main qualities:
INVERTER | QUALITIES |
Centralized inverter | ✅ One inverter for the entire system ✅ Suitable for large systems ❗ Does not allow control of each string |
String inverter | ✅ One inverter for a single string ✅ Multiple inverters for the entire system ✅ Suitable for residential and commercial systems ✅ Cheaper ❗Not suitable for less sunny areas |
Micro inverter | ✅ An inverter for a single panel ✅ Multiple inverters for the entire system ✅ Suitable for plug and play systems ✅ Continuous monitoring of each panel |
Centralized inverter for large systems
Central inverter transforms direct current coming from entire system. It is used for large systems and, It is single inverter connected to all strings: in this way it allows simple and direct conversion, but does not guarantee in-depth control of performance of each individual module or string.
Generally, it is preferable to place central inverter inside building, away from temperatures that are too high or too low.
In summary, it is ideal inverter for:
- Anyone who has a large system to power.
- For those who want a simple conversion and do not need panel-by-panel control.
String inverters for residential systems
The string inverter collects direct current from string of panels. In this case, monitoring it performs is focused on the overall power generated by string, and not by the system. It is cheapest inverter on market and is easy to maintain, furthermore it is recommended especially for very sunny areas.
String inverter is one used mainly for commercial and residential systems: if you prefer this option, you will have to get as many inverters as there are strings in your system. Like centralized inverter, string inverter is also more protected if placed inside sheltered room.
String inverter is perfect for:
- Anyone who wants to power their home utilities
- Who doesn’t want to spend too much
Micro inverter for plug and play systems
While central inverter is connected to entire system and string inverter measures performance of individual string, micro inverter, on other hand, connects to individual solar panel.
This is installed behind single panel and therefore allows each module to produce energy that can be used by users. Each system, therefore, will have as many inverters as there are panels.
Micro inverters, being part of system with much more modular structure, have 2 main advantages:
- It is right tool for system that needs to be expanded, simply by adding each panel with its own inverter.
- Allows you to monitor performance of individual modules in detail.
Micro inverter is also an inverter used for plug and play systems, very small systems with power less than 350W.
It is ideal inverter for:
- Who wants to pay close attention to performance of each module and possible failures
- Anyone who has facility that they would like to expand
- Who has plug and play system?
Hybrid inverter for systems with storage
If inverter is to be connected to system with storage systems, choice falls on hybrid inverter
A hybrid inverter, in addition to converting direct current into alternating current, also manages charge and discharge flows of energy in storage systems.
Hybrid inverter, therefore, is also Battery Management System, that is, it allows you to manage:
- Flow of alternating current that powers home’s utilities
- Flow of unused energy, which must be stored in accumulators
- Feeding generated energy into grid when battery is fully charged
This type of inverter, therefore, is of fundamental importance for correct functioning of storage system: by optimizing these flows it is able to guarantee an ever-increasing percentage of self-consumption, and therefore savings on the bill.
A hybrid inverter, depending on type of connection it has with system, can still be centralized, string or micro.
Hybrid inverter without grid feed-in for stand-alone systems
Stand-alone or off-grid solar system is system not connected to electricity, so it relies exclusively on energy produced by panels and then stored in storage systems.
When energy produced by panel is not enough, only other power source is that coming from batteries, for which accumulators are needed that can store large amount of energy.
In this system, inverter must also have excellent performance. Inverter used for an off-grid system is similar to hybrid inverter: its function is therefore to manage energy flows from panels to the accumulators and from accumulators to users, without however feeding excess energy into grid.
Choosing an isolated system is ideal for those who want to achieve complete independence from electricity grid, and therefore for those who no longer want to receive bills.
How to choose solar inverter
If you have understood which type of inverter is best for you but you still don’t know which one to choose, you must consider an important factor, namely power, which must be proportionate to that of system.
However, power of inverter does not have to be equal to that of system, because there are moments or periods of strong solar radiation, and therefore production peaks.
Inverter must be able to handle these power peaks, in order to avoid possible efficiency problems and damage to system. For this reason, it must have power slightly greater than that of panels, for example, if system is 3kW, inverter must have power of about 3.5kW.
Power of an off-grid inverter must necessarily be calculated on basis of maximum peak energy load, maximum power reached in very short time: this is approximately 25-30% higher than power of system.
Solar Panel Inverter: Prices
How much will the inverter you choose for solar system cost you? Here too, you need to make distinction and select prices carefully.
Economic value of an inverter is determined by some variables:
- Type of inverter chosen: single-phase or three-phase, centralized, string or micro
- Power required for its proper functioning.
- System in which it will be positioned: without storage, with storage or isolated.
Prices of solar inverters range from PKR 80,000 or 120000 for micro inverters to PKR 400,000 for three-phase 5kW solar inverters.
Frequently Asked Questions about Solar Inverters
Inverter for solar serves to transform direct current produced by panels into alternating current, making it usable for utilities. It also has function of protecting systems from possible failures.
Average lifespan of string solar inverter is 10-12 years. Micro inverters, on other hand, last an average of 20 years.
Since it is device with many electrical components, it is generally better to protect it from heat sources, although some models protected by casing can be installed outside. They must be as close as possible to panels: microinverters, for example, can be mounted behind modules.