In this article, we explain what these terms mean, what the differences are, and when to choose which solution. This way, you always help your customer with a suitable and efficient installation.
Note: in most cases, a kWh meter is required with data cabling to the inverter, unless you are working with exceptions such as Sessy, the GroHomeManager-X, or Bliq EMS.
Which battery installation suits your customer?
Not every situation is the same. Therefore, it is important to clearly identify the customer's wishes:
Does the customer want to install the battery with the existing PV inverter?
Is there already a hybrid inverter present?
Is there a need for brand independence or flexibility in location?
Is it desirable to expand an existing system with storage?
Broadly speaking, we distinguish two main types of battery installations:
Hybrid system
Retrofit system
In this article, we explain what both systems entail, what the pros and cons are, and what the installation looks like. This way, you and your customer always choose the right solution together.
Important: For most systems, a kWh meter is required that communicates wired with the inverter via Modbus RS485. There are a few exceptions, such as Sessy, Bliq EMS, and the GroHomeManager-X.
What is a hybrid system?
A hybrid system means that the solar panel inverter is also suitable for connecting a battery. This provides a direct DC-DC connection between the solar panels and the battery – which offers efficiency advantages. Additionally, this is the least complex installation.
When do you choose a hybrid solution?
The customer wants to place the battery with the PV inverter:
| Situation | Approach |
|---|---|
| There is already a hybrid inverter present | Install a battery that fits the inverter. |
| There is a hybrid inverter present, but the customer prefers a battery of a different brand and/or type | Use a Sessy battery or replace the inverter with the desired brand. |
| There is no hybrid inverter present yet | Use a Sessy battery or replace the inverter with the desired brand. |
What is a retrofit system?
A retrofit system is applied when the battery is placed separately from the existing PV installation – for example, in a different location or on a separate circuit in the consumer unit. This offers more flexibility in placement and brand choice.
When do you choose a retrofit solution?
If the customer wants to install the battery in a different place than the current PV installation.
If there are multiple PV systems, but the battery is connected to only one system or to no system at all.
Advantage of retrofit: less brand dependency and more freedom of choice regarding location.
Advantages at a glance
| Feature | Hybrid | Retrofit |
|---|---|---|
| Efficiency | Higher (DC to DC) | Lower (conversion DC → AC → DC) |
| Installation location | At inverter | Location freely chosen |
| Brand independence | Limited (varies per situation) | High |
| Installation complexity | Lower | Slightly higher (depending on brand and system) |
What the installation looks like
Hybrid installation
In a hybrid installation, the battery is connected directly to a hybrid inverter. A kWh meter is mandatory, except for systems such as Sessy (which uses the smart meter). Communication runs via Modbus RS485 (data+ / data–, optionally GND). In some cases, wireless (RF) communication is also possible, such as with the GroHomeManager-X and Bliq EMS.
Example:
PV inverter = hybrid
Battery connected via DC
kWh meter with Modbus connection
Source: Bliq
Retrofit installation
With retrofit, you place the battery on a separate circuit, apart from the PV installation. PV can also be connected to the inverter – this is still considered retrofit. Sometimes it is also necessary to measure the PV yield of the other inverter(s). However, this differs per product. At the bottom of this article, you will find an overview.
The most important: the battery must know what is happening at the main connection. So: always measure at the main connection before any consumption, via a kWh meter or smart meter*. The example below shows a single-phase retrofit with Growatt.
Note: there is also a wired communication from the inverter to the battery here.
* Only possible with specific products
source: Growatt
Multiple PV systems?
If there are multiple PV systems besides the inverter with battery, it may (depending on the brand) be necessary to measure the total yields. For this, you can do the following:
Combine the yield before the CT coils into one cable.
Example: single-phase Growatt retrofit with combined PV generation.
For 3-phase: note that a maximum of 3 coils can be used on the main connection and 3 coils for PV generation.
Overview per brand & communication
| Manufacturer | Product | Installation requirements | Communication |
|---|---|---|---|
| Huawei | Smart Power Sensor | Maximum 2 sensors: one at the main connection, one at the PV circuit. Both connect to the inverter. | RS485 |
| Huawei | Smart Assistant: EMMA | EMMA at main connection + power sensor or CTs on PV circuit (PV measurement optional) | RS485 |
| Enphase | Gateway Metered | Main connection + full PV yield | RS485 (via adapter) |
| Sessy | P1-/CT dongle | Smart meter or CT dongle | Wifi/Ethernet |
| Growatt | Smart Meter | Main connection (optional: PV yield with max. 6 CTs: 3 for main connection, 3 for PV) | RS485 |
| Growatt | GroHomeManager-X | Main connection (measuring PV circuit optional) | RS485 or RF |
Note: When the PV circuit is not measured, the battery will function correctly, but the consumption data is incomplete. Part of the PV yield is then consumed directly in the house, and this data is not visible in the monitoring.
Finally
Hybrid or retrofit – both solutions have their place. It depends on the situation, wishes, and existing systems. Unsure? Contact one of our specialists. We are happy to think along with you.
📧 support@4blue.nl
📞 (024) 204 20 90
👉 Want to know more about our battery solutions?
Visit our category page for storage systems or view more knowledge articles.
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