I am planning to use Victron Energy products in my home, which is supported by solar panels. Specifically, I intend to install:
2 x MultiPlus-II 48/5000/70-50
10 kWh solar panel system
20 kWh lithium battery bank
Supported by GX devices
My home has a 230VAC grid connection. My question is: while the inverter loads in the house reach a maximum of around 6 kW (which I understand how to support through inverter, battery, and solar sources),
but I also have a 15 kW heat pump, Is it possible to program the system to power this load using the 2 pcs Multiplus II with Power Assist—for example, supplying 8 kW from solar and drawing 10 kW from the grid when solar production is high?
I have a basic understanding of system configuration via VE.Configure, and I would like to know if setting this up via ESS programming would be sufficient to manage this scenario.
It is a good idea to brush up on the tech both via the ESS design and install guide and the free online training.
Power assist is a tech that is separate for non-ESS systems.
By default in an ESS using self-consumption modes, the loads are covered from the battery, up to any inverter/discharge limits, after which grid is used for the balance.
When below battery thresholds, loads are serviced by grid.
Thank you for your response — it’s reassuring to hear that.
So, when the 15–18 kW heat pump is running and the grid is available, my two MultiPlus-II 48/5000 units (totaling 10 kVA) will not go into overload. Around 8 kW will be supplied from the batteries and solar panels, and the rest will be balanced via the grid using PowerAssist.
This brings up another question:
In the event of a grid outage, how do the MultiPlus inverters protect themselves from overload?
Based on your experience, would you recommend expanding my inverter system or supplementing it with another solar inverter? For very occasional uses, installing the necessary heat pump system would be quite costly.
You can set a lower limit in ESS as well, but the multis can passthrough power up to the rating of the transfer switch.
If you lose grid and overload the inverters they will eventually either shutdown with a thermal fault or just turn off due to overload. In the latter case they will try restart 3 times and will eventually just stop until load is reduced.
You could also connect the heatpump to AC OUT 2 which is automatically dropped when grid is lost.
Thank you for your support, everything is clearly explained in the ESS documentation.
I believe it would be beneficial to place a Siemens Voltage Monitoring Relay in front of the heat pump and other high-kW loads to protect the MultiPlus in the event of a grid outage. This way, those heavy loads will be disconnected when the grid is down.
I’m also assuming that AC OUT 2 is not powered by solar panels, so relying on it for backup may not be effective in this case.
Both outputs are powered by the inverter/solar. AC OUT 2 is just a branch off AC OUT 1, so it behaves the same, except it is dropped when grid fails.
There is also an assistant that can override the behaviour of AC OUT 2 as well.
No need to add extra devices, just use AC OUT 2.
Are you sure 15-18kW is Heat Pump electrical absorbing power and not heating/cooling equivalent performance? Usually when naming “15kW HP” we mean its heating/cooling power. Given a COP/SER factor of e.g. 3, this means 5kW absorbing power from the mains.
[There might exist some resistors, for extreme low temperatures, e.g. below -7c, so take into account these, or do not connect them if you can live with this]
And anyway, 18kW in 1-phase means 80A..! I am not aware of such 1-phase HP models.
So, maybe this changes your calculations. Be sure to read the HP specs.
(and drive the HP from AC Out2, as Nick suggested)
To be honest, I am still in the process of calculating these consumption values. For the house, I will likely need a 15 kW heat pump. Whether it will be single-phase or three-phase will depend on the specific products I decide on once everything is finalized.