1. Inverter – why is it such an important element of the installation?
When choosing a photovoltaic installation, most people pay attention primarily to the power and parameters of the panels. Meanwhile, an equally important element of the entire system is the inverter, also known as a solar inverter.
It is responsible for converting DC direct current produced by photovoltaic panels into AC alternating current, which can be used by electrical devices in a home or business.
However, a good inverter should do much more than just convert DC to AC. In a modern installation, it can manage energy production, cooperate with the grid, support energy storage systems, monitor the installation's operation, and even provide emergency power.
Therefore, choosing the right device should be one of the most important stages of designing a PV installation.
2. First, determine what type of installation you need
The first question should be:
What is my installation supposed to be used for?
There are three basic solutions on the market:
ON-GRID
An on-grid system cooperates with the public power grid.
The energy produced by the panels is used on an ongoing basis, and surpluses can be fed into the grid in accordance with applicable billing rules.
This solution is most often used in classic residential and commercial installations.
OFF-GRID
An off-grid system operates independently of the public power grid.
It requires appropriately selected energy sources and usually an energy storage system, as PV production varies throughout the day and year.
Such solutions can be interesting, for example, in places without grid access.
HYBRID
A hybrid system combines the advantages of on-grid installations and energy storage.
A hybrid inverter can work with both the grid and a battery.
During the day, energy can power the home, charge the storage, and surpluses can be sent to the grid. In the evening, the energy stored in the battery can be used to power receivers.
For new installations that are to be prepared for future development, the hybrid solution is often a very interesting option.
3. How to choose the right inverter power?
This is one of the most important parameters.
Let's assume the installation has:
10 kWp of photovoltaic panels.
Do we need a 10 kW inverter?
Not necessarily.
In practice, the power of the PV generator can be greater than the nominal power of the inverter. This is due, among other things, to the fact that panels rarely operate at maximum nominal power for a long time.
Therefore, designers can use some oversizing of the DC side relative to the AC side.
For example:
10 kWp panels + 8 kW inverter
can be a correctly designed system – but only if the parameters of the specific device, location, and installation configuration match.
Therefore, one should not choose a device based solely on a simple formula:
panel power = inverter power.
Each manufacturer specifies the maximum PV generator power, MPPT voltage range, and maximum input current. These parameters must be checked before purchase.
4. MPPT – a parameter you should not ignore
One of the most important technical parameters to pay attention to is the number of MPPT trackers.
MPPT, or Maximum Power Point Tracking, allows the inverter to search for the operating point at which the installation produces the most energy possible.
This is extremely important when panels are located on different roof sections.
Example:
South-facing roof section → 10 panels
West-facing roof section → 10 panels
If both groups of panels have different sun exposure conditions, it is worth considering a configuration with independent MPPT trackers.
The situation is similar in the case of partial shading.
Therefore, when choosing an inverter, you should check not only:
"How many kilowatts does it have?"
but also:
"How many independent MPPTs does it have and what voltage range do they support?"
5. Inverters and energy storage systems
The PV market is rapidly moving towards the integration of energy production and storage.
Therefore, if you plan to purchase a battery in a few years during the installation design phase, it's worth thinking about it today.
Not every classic inverter will work with energy storage systems.
If you plan to have storage, you might consider:
hybrid inverter + battery
This solution allows you to integrate PV energy production, storage, and energy management.
For example, during the day:
PV → home + battery charging
and in the evening:
battery → home
In the event of a grid outage, a properly configured system can also provide emergency power to selected circuits.
This is why hybrid inverters are becoming an increasingly interesting solution for new installations.
6. Is it worth buying a hybrid inverter even if I don't have a battery yet?
It depends on the investor's plans.
If energy storage is not being considered at all, a classic on-grid inverter may suffice.
However, if there is a high probability that energy storage systems will be introduced in one, two, or three years, it is worth considering a hybrid device from the outset.
This avoids a situation where, after a few years, it becomes necessary to replace the entire inverter just because we want to add a battery.
However, it should be remembered that a hybrid device may cost more than a simple on-grid inverter.
Therefore, the decision should stem from the planned use of the installation, and not from the mere trend of storage.
7. Backup – what happens during a grid failure?
This is a very often overlooked topic.
Many people believe that if they have photovoltaic panels, they will still have electricity during a grid failure.
Not always.
A standard on-grid installation usually switches off in the event of a grid voltage drop. This is due to safety requirements for grid-connected installations.
If we want to have energy also during a failure, the system must be properly designed.
It can then use:
panels + hybrid inverter + energy storage + backup/EPS output.
Depending on the device, selected circuits can be powered, e.g.:
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refrigerator,
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lighting,
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router,
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alarm system,
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basic electronic devices.
Before purchasing, it is therefore worth checking whether a specific inverter has a backup function and what its limitations are.
8. Inverter for home, business, or photovoltaic farm?
A home installation will have different requirements than a small business, and a PV farm will have yet another set of requirements.
HOME
Devices with a power of several or a dozen kW are most commonly used.
It is worth paying attention to:
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number of MPPTs,
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cooperation with storage,
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monitoring,
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backup function,
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ease of configuration.
BUSINESS
For a business, the following are important:
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higher power,
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expandability,
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monitoring of multiple devices,
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reliability,
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service,
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ability to integrate with EMS.
PV FARM
Here, the most important aspects become:
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power,
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efficiency,
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number of MPPTs,
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maximum DC voltage,
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monitoring capabilities,
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resistance to environmental conditions,
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service and parts availability.
Therefore, there is no single "best inverter."
However, there is an inverter that is best suited for a specific installation.
9. What technical parameters should you pay attention to?
Before purchasing, it is worth creating a simple checklist.
Key parameters:
AC Power
Does it match the planned installation?
Maximum PV power
How many kWp of panels can be connected?
MPPT voltage range
Does it match the configuration of the panel strings?
Number of MPPTs
Does it allow for proper operation with different roof sections?
Maximum input current
Especially important for modern modules with high current.
Efficiency
Affects energy losses during conversion.
IP rating
Important if the device is installed in demanding conditions.
Communication and monitoring
Wi-Fi, Ethernet, RS485 or other solutions allowing for installation control.
Battery compatibility
Crucial if you plan energy storage systems.
Backup / EPS
Important if the installation is to operate during a grid failure.
10. Which inverter to choose? Summary
Choosing an inverter should not start with the question:
"Which inverter is the best?"
It should start with:
"How should my installation work?"
If you need a simple system that works with the grid – consider an on-grid solution.
If the installation is to operate independently of the grid – you need a properly designed off-grid system.
If you want to combine photovoltaics, the grid, and a battery – a hybrid system will be an interesting solution.
For new installations, it is also worth thinking long-term. The market development means that energy storage systems are becoming an increasingly important element of PV systems, and a well-chosen inverter can be the heart of the entire installation.
A well-chosen inverter should work with panels, the grid, an energy storage system, and an energy management system.
It is the integration of these elements that will be one of the most important directions of Renewable Energy development.
myPVOutlet.eu – choose a system, not a single device
A modern photovoltaic installation is not just about panels.
It's an entire system:
photovoltaic panels + inverter + energy storage + monitoring + smart management.
Therefore, before purchasing a device, it is worth checking all technical parameters and matching them to the specific installation.
A good inverter is not the one with the most features. It is the one that works best with the entire installation today and allows for its expansion in the future.