Replacing the inverter with a hybrid one – does it always make sense?
More and more owners of photovoltaic installations are considering replacing a regular inverter with one hybrid inverter. The reason is simple: self-consumption is becoming more and more important, and the energy storage allows for better use of the electricity produced from the panels.
However, you have to be careful. Replacing an inverter is not always a simple "take out the old one, put a new one in.” In practice, you need to check compatibility with the energy storage, phase arrangement, protection, backup (emergency power supply), notification to the operator and profitability of the entire investment.
What is the difference between a regular inverter and a hybrid inverter?
A regular photovoltaic inverter converts direct current from PV panels into alternating current used at home or fed into the network. It does not directly support energy storage.
Hybrid inverter can also work with a battery. Can charge energy storage from photovoltaics, discharge it in the evening, limit the energy released to the grid and in some configurations power selected circuits during a network failure.
| Inverter type | Energy storage service | Backup (emergency power supply) in the event of a network failure |
|---|---|---|
| Ordinary PV inverter | No, without an additional system | Usually not |
| Hybrid inverter | Yes, if the battery is compatible | Only with EPS/backup function (emergency exit/emergency power supply) and proper connection |
When does replacing the inverter with a hybrid one make sense?
Replacing may be a good idea if:
- you have a lot of surplus energy at noon;
- you want to add energy storage;
- you use a lot of electricity in the evening and in the morning;
- you want to limit energy released into the grid;
- the old inverter is nearing the end of its warranty;
- you are planning a major modernization of the PV installation.
Replacing makes less sense if the current inverter is new, works stably, and you are not sure whether you will actually buy an energy storage unit in the near future.
The most important things to check before replacing
1. Compatibility with energy storage
This is the most important point. Not every hybrid inverter works with every battery.
- list of officially supported energy storage facilities;
- minimum and maximum battery capacity;
- battery voltage: high voltage or 48V;
- possibility of expanding the warehouse in the future;
- warranty conditions using a specific battery;
- website availability in Poland.
2. Is the system supposed to function as a backup (emergency power supply)?
For the system to operate in an emergency, the following are needed: function EPS/backup (emergency exit / emergency power supply), appropriate energy storage, network-emergency power switch and separate emergency circuits or a complete home emergency power system.
3. Backup (emergency power supply) 1-phase or 3-phase?
In Poland, many houses have a 3-phase installation. Some hybrid systems can operate on a 3-phase network, but in the event of a failure, they only power one phase.
| Item to be checked | Why is it important? |
|---|---|
| Backup (emergency power supply) 1-phase / 3-phase | Decides which devices will operate after a power outage. |
| The power of continuous backup | Shows how many devices can be powered at the same time. |
| Peak power | Important for pumps, compressors, refrigerators and heat pumps. |
| ATS (automatic switch) / backup box (emergency power supply module) | Safely disconnects your home from the network during a power outage. |
| Black-start (starting without mains power) | It allows you to start the system when the network is completely turned off. |
4. The backup power (emergency power supply) may be lower than the inverter power
A 10 kW hybrid inverter does not always mean 10 kW available during a grid failure. Often the power of backup is lower and the maximum power per phase is additionally limited.
5. Do you need to replace the protection and switchgear?
Replacing an inverter often requires additional electrical work. The cost of modernization is not only the price of the device.
- dismantling the old inverter;
- installation of a new inverter;
- new DC/AC protections;
- smart meter or energy meter;
- cabling for energy storage;
- backup box (emergency power supply module) or ATS (automatic network-emergency power switch);
- system configuration and documentation.
6. Is it worth keeping the old inverter?
It is not always necessary to replace the current inverter. Sometimes a system is a better solution AC-coupled (energy storage connected on the AC side), i.e. adding a separate battery inverter to the existing PV installation.
Consider when your old inverter is old, out of warranty, or planning a major upgrade.
Consider when your current inverter is new, works well and you don't want to rebuild the entire PV installation.
7. Does the PV power match the new inverter?
When replacing, you need to check the parameters of the PV strings:
- MPPT operating voltage (maximum panel power point tracking system);
- maximum DC voltage;
- maximum input current;
- number of strings;
- panel orientation;
- installation power relative to the inverter power.
8. Will the energy storage be selected appropriately?
A warehouse that is too small will fill up quickly and will not solve the problem of energy surpluses. Too big will be expensive and may pay off more slowly. Battery selection should depend on evening and morning consumption, PV size, the presence of a heat pump, charging an electric car, tariffs and the need for backup.
9. Does the system have EMS?
A hybrid inverter alone is not always enough. It is becoming more and more important EMS (energy management system), i.e. system energy management. A good EMS can control the battery, heat pump, boiler, EV charger and limiting feeding energy into the grid.
The most common mistakes when replacing an inverter with a hybrid one
Mistake 1: Buying an inverter without checking the battery
The user buys a hybrid inverter and only then checks the energy storage facilities. It may turn out that compatible batteries are very expensive or difficult to obtain.
Mistake 2: assuming that backup works automatically
Backup (emergency power supply) requires appropriate installation design. If there is no ATS (automatic network-emergency power switch), backup box (emergency power module) or separate circuits, the system may not power your home during a failure.
Error 3: not taking into account the 3-phase installation
In a 3-phase house, you need to be especially careful about how the inverter works. Backup (emergency power) 1-phase may be insufficient.
Mistake 4: choosing an energy storage unit that is too small
A small battery may improve auto consumption, but it will fill up quickly. Then the surpluses will still go into the network.
Mistake 5: Only looking at the inverter price
The total cost also includes installation, security, counter, configuration, backup equipment (emergency power supply) and any works in the switchboard.
Questions to ask your installer
Before signing the contract, it is worth asking the installer specific questions:
- Does the inverter support the energy storage I want to buy?
- What batteries are officially compatible?
- Is backup (emergency power) 1-phase or 3-phase?
- What is the power of continuous and temporary backup (emergency power supply)?
- Does the price include a backup box (emergency power module), ATS (automatic network-backup switch) or smart gateway (energy management gateway)?
- Does the switchboard need to be modernized?
- Will the current PV string fit the new inverter?
- Does the system have the option of black-starting (starting without mains power)?
- Will I have full access to the application and administrator account?
- What is the warranty for the inverter, battery and installation?
Check out the recommended hybrid inverters for energy storage
Compare 1-phase and 3-phase models, backup support (emergency power supply), compatible batteries and approximate installation costs.
See the inverter comparisonFAQ
Does every hybrid inverter work with energy storage?
NO. Each manufacturer has a list of compatible batteries. Before purchasing you need to check whether selected the energy storage is officially supported by the inverter.
Does the hybrid inverter work during a power outage?
Only if it has a backup/EPS (emergency power supply/emergency exit) function and the installation has been properly performed. It is often needed additional backup box (emergency power supply module), ATS (automatic network-emergency power switch) or separate emergency circuits.
Is it possible to replace a regular inverter with a hybrid one without changing the panels?
Often yes, but you need to check the parameters of the PV strings (strings of panels connected in series), voltages, input currents and the number of MPPTs (systems tracking the maximum power point of panels). Not every inverter will fit the old panel layout.
Which is better: hybrid inverter or AC-coupled?
A hybrid inverter is a good choice for a new installation or major modernization. AC-coupled may be better when the existing PV inverter is new and working properly.
Is it worth buying a hybrid inverter without batteries?
You can, but it only makes sense if you plan to purchase energy storage in the near future. Otherwise, you're paying for features you don't use yet.
Glossary of technical terms
The following terms often appear in installers' offers. It is worth knowing them before signing the contract, because they determine the actual operation of the hybrid inverter, energy storage and emergency power supply.
| Concept | Simple explanation | Why is it important? |
|---|---|---|
| Hybrid inverter | A PV inverter that can work with an energy storage facility. | Without a compatible battery, some of its functions remain unused. |
| Energy storage | A battery that stores excess electricity from photovoltaics. | It helps increase autoconsumption and reduce energy input to the grid. |
| Backup / EPS | Emergency power supply activated in the event of a power outage in the network. | Not every hybrid inverter powers your home during a failure. You need to check the EPS mode and connection method. |
| ATS | An automatic switch that disconnects your home from the grid and switches it to emergency power. | It protects the network and installation against dangerous discharge of electricity during a failure. |
| Backup box | Additional manufacturer's module for emergency power supply. | It is often required, but not always included in the base price of the kit. |
| Black-start | Ability to run the system when the power grid is completely turned off. | Without this function, the system may not start despite the presence of batteries or PV panels. |
| AC-coupled | Energy storage added on the AC side, usually without replacing the current PV inverter. | It may be a good solution when modernizing an existing installation. |
| DC-coupled | Energy storage connected on the DC side, usually directly to a hybrid inverter. | It may be effective in a new installation, but it binds the user more closely to a specific system. |
| MPPT | A system in the inverter that optimizes the operation of PV panels. | When replacing the inverter, you need to check whether the current PV strings match the MPPT inputs. |
| String PV | A chain of photovoltaic panels connected in series. | Wrong selection of string voltage or current may prevent the new inverter from operating properly. |
| Smart meter | Intelligent energy meter measuring electricity consumption and dissipation. | It is needed to control the battery, limit exports and monitor consumption. |
| EMS | Home energy management system. | It helps you control your battery, heat pump, boiler or EV charger. |
| Continuous power | The power that the inverter can supply for a longer period of time. | It shows how many devices can realistically be powered during a failure. |
| Peak power | Short-term overload power available for a few or several dozen seconds. | Important for devices with high starting current, e.g. pumps, refrigerators and compressors. |
| 1-phase / 3-phase | A way to power your home and distribute electrical loads. | In a 3-phase house, a 1-phase backup can power only part of the circuits. |
Summary
Before replacing a regular inverter with a hybrid one, first of all check its compatibility with the energy storage system, backup (emergency power supply) 1-phase or 3-phase, backup power, need for a backup box (emergency power supply module) or ATS (automatic network-emergency power switch), possibility of battery expansion, parameters of current PV strings and costs of switchgear modernization.
A well-selected hybrid inverter can increase auto consumption and prepare the house for energy storage. However, if chosen incorrectly, it may become an expensive element that does not meet the user's expectations.