I would like to install a 24V 440Ah battery bank with solar panels so that I can use the batteries at the end of the day. I already have a solar installation for self-consumption and selling the surplus, and I am connected to EDF. The current solar installation feeds directly into the household’s 230V network and, for safety reasons, the microinverters have to be powered by EDF, so the system cannot operate off-grid.
Which Victron products would allow me to set up this installation, which I would like to operate as follows:
I would like to charge the batteries using a standalone system, while continuing to use my existing solar installation.
I would like this battery bank to be charged by another installation.
I currently have a 4.8 kW Hoymiles microinverter installation for self-consumption and selling surplus electricity, with the 230 V coming directly from the roof.
Okay, I think I understand:
You are keeping your current installation as it is.
You are installing a separate PV system dedicated to charging a battery bank.
The battery bank will power your house and keep your Hoymiles inverters running in the event of an EDF power cut.
Have I got that right?
Why 24 V batteries? This is an important consideration in helping you with your project.
24 V products are more expensive than 48 V products. You can easily find reliable 48 V batteries that are compatible with Victron (and compliant with IEC 62619, which is important for CONSUEL approval).
I’d like to be able to use the batteries in the evening, when my current system is no longer supplying power.
Switch to the battery bank in the evening. The batteries won’t be a problem: I can provide 48 V. I have four 12 V, 220 Ah gel batteries, plus two more AGM batteries with the same capacity.
Okay, understood — you’ve come to the right place : the Victron community.
You should consider the Smart RS Solar 6KVA. It’s an all-in-one product, and you can use AC coupling, i.e. use your existing installation to recharge the battery. You can also add up to 6 kWp of PV on the DC side. It’s a very easy product to install.
Have you understood the operating principle of the ESS? This is at the heart of how energy management works. The system manages the battery by charging and discharging it according to demand. It does not switch over at a specific point that you have defined. Instead, it constantly adjusts itself according to demand in order to balance the reference point (usually the grid input).
A mix of lead-acid batteries (gel and AGM) is not ideal, but if you already have them, why not try to get the most out of them? You should not expect a very long service life, as these batteries are not particularly well suited to this type of use. With this type of battery, it is recommended that you avoid discharging them too deeply, which reduces the amount of energy that can actually be used. In practical terms, a 200 Ah lead-acid battery cannot deliver as much energy as a 200 Ah lithium battery without risking premature damage.
The choice of product will depend on your project. The Multi RS Solar is a versatile product that allows you to start with just the storage system and add solar panels later. An ESS management unit is integrated into it. However, if necessary, it can also be controlled by an external unit, a GX device (Cerbo GX or Ekrano GX).
Other accessories will be required to complete the installation.
Great, thanks for the information. I was thinking of using an ET112 meter, a Cerbo GX and a MultiPlus II. I already have an MPPT 150/35, a BMV-712 with SmartSwitch, four 12V 220Ah Gel batteries and, for the moment, three 210W panels.
Is this configuration suitable for what I want to do?
That sounds good. The MPPT 150/35 and the BMV 712 are fully compatible with 48 V batteries. As Patrick said, opting for a 48 V MultiPlus-II will be more economical than a 24 V one. When the batteries reach the end of their service life, it will be easier and more economical to replace them with a 48 V lithium battery.
Good luck finding an ET112. They’re out of stock everywhere. Other meters are available.
A 3 or 5 kVA MultiPlus-II, or a 4.5 kVA MultiPlus-II, will be more than sufficient. To keep costs down, you could also opt for the same products with an integrated GX: the MultiPlus-II GX 3 or 5 kVA, or the MultiPlus-II GX 4.5 kVA.
The Battery Balancer is an accessory worth considering. But is it worth the cost?
Returning to Patrick’s suggestion, the Multi RS Solar alone replaces the MPPT 150/35, the BMV712, the MultiPlus-II and the Cerbo GX. In short, it makes installation much easier and could even result in some savings.
Make sure you plan your project carefully, particularly the cables, DC and AC protection devices and isolators, surge protectors, and so on. A diagram is always useful. Finally, validation by CONSUEL will give you certainty that you have carried out a compliant and properly protected installation.
Have you ever carried out this kind of installation with protective devices such as, I think, Mega Fuses? If you could provide me with a basic schematic showing the protective devices, that would help me a lot, as I’m just starting out with this kind of installation. Many thanks.
Can a single Battery Balancer manage all four batteries? Based on the diagrams I’ve found, you would need three for four batteries in series—is that right?
When using ESS, non-LFP batteries will age a lot. You might cycle every day.
Please plan the upgrade to managed LFP within 2 years.
Considering the remaining lifetime of the AGM batteries, I would not buy balancers.
A managed 16kWh 48V battery is appr. 1.600 EUR.
Please consider mandatory batteries sizes depending on MP2/RS size and AC-coupled PV on AC_out.
I have MP2 and Hoymiles running. Please find the details in my build thread linked in my profile.
: the Victron community.