I’m having a Victron setup (Multi RS Solar, 2x PV chargers, Cerbo, 32Kw battery, EV charger) running (stil in 2026) in DESS mode. Will be changed on 1 Jan 2027 as the rules with returning solar energy to the grid are changing in The Netherlands. Now I’m considering, investigating if I can get a heatpump and get disconnected from gas. The hearpump probably comes with a warm water boiler. My question: how does this effect the whole Victron setup and beging controlled from the Cerbo? Should the heatpump and water boiler be integrated into the Victron system so that they know about these energy users? How would that work? How can I centrally control this (if needed). Any advice? Any experience on this?
The heat pump primarily draws power when solar output is low. Consequently, the goal is simply to charge the battery using grid power during periods of low electricity prices in order to avoid drawing from the grid during expensive periods.
Since it makes no difference whether expensive electricity is used for the heat pump or the coffee machine, I consider it pointless to specifically integrate the heat pump into the Victron DESS; it is just another electrical load among many. In principle, however, it would likely be quite easy to incorporate the heat pump into the DESS control system using Node-RED. Yet, I am certain that doing so would offer no advantages.
Is the price spread between peak and off-peak times for dynamic electricity tariffs greater in the Netherlands than in Germany? In Germany, due to the narrow spread, dynamic tariffs may be worthwhile for industry and commercial businesses, but almost never for private households.
Im running a heatpump from feb this year, its a bosch 5800iaw os7 air water 2.7kW oudoor unit and 9kw indoor (limited to 3kw), its on ac out of my 3ph 5k multiplus 2 ESS setup, i have an energy meter on the 1ph outdoor unit and a seperate on the indoor unit (3ph), both are for now setup as evcs meters
Heatpump is not visible on vrm yet, hence the evcs setup
however im also running home assitant with a great integration called PV excess control, it can integrate PV, battery, heatpump, EV, dynamic tariffs, airco and other power users
this integration gives a signal to my heatpump when there is excess PV (smart grid) and uses that to heat the boiler when needed,
we also have a solar boiler system connected to it so most part in summer water is heated by solar boiler and i use excess PV now to let the heatpump cool our house all controlled by that integration
It also controls the LG airco thats in the attic
We have no dynamic contract, makes no sense for me right now to do that, maybe in 2027 when new “rules” become clear
The most energy intense application is hot water production because of the way higher temperature setpoint required.
Doing this during noon is the most logical thing for two reasons:
- Probably most solar output within 24h
- Probably highest ambient temperature, therefore lowest temperature lift required.
Running the heatpump in the night therefore is a 2 times bad practice and usually only required on very few, very cold days, where the thermic latency of “everything heated up” is not enough to keep it comfy.
But if you just referred the general solar difference between summer / winter, then I agree 
I never run my heat pump at night. I prefer sleeping in a cooler room, which allows the heat pump to operate with maximum efficiency. Besides, my house is so well insulated that even on cold days, the heat pump only needs to run at its lowest output.
Something else was important to me: in winter, I don’t generate enough solar power to cover my electricity consumption anyway. So, whether or not the solar power contributes to running the heat pump doesn’t really matter, since I use up all the solar energy I generate regardless. It makes no difference whether I use the electricity for the heat pump or for the coffee machine.
I assume you use the same heat pump for both space heating and hot water. It’s different in my case; I generate hot water independently of the heating system.
Thanks for the additions into this conversations. I’m still discovering and exploring.
The conclusion sofar, installing a heatpump and a warm water boiled doesn’t mess up the Victron installation etc. As it can be seen similar as a coffee machine or washing machine. Good to know. The other topic raised above is when best to switch on the heatpump and/or the boiler, during the day when there is enough solar or in the evenings using the energy from the batteries. My conclusion from this is that you need to select a heatpump/boiler which can be controlled through for example Home Assistant, then you have the flexibility to control this.
Thanks for the support and more comments/different views are always welcome. Cheers.
Since you asked for it:
When designing a solar system for a household with a typical load profile, I would proceed as follows:
- Solar module capacity – I would base this on average daily consumption; for instance, with a daily consumption of 7 kWh, I would install 7 kWp of modules. Since modules are very inexpensive, it is better to install more rather than less—especially if you receive compensation for feeding surplus power into the grid.
- Inverter capacity – Unlike the standard practice among solar installers, I would base this on the load profile rather than the installed solar capacity. Aiming for 100% self-sufficiency makes no sense. It is not a problem if the load exceeds the inverter’s output capacity for just a few minutes a day; sizing the inverter to handle peak loads would be highly uneconomical. The vast majority of households can easily manage with a single-phase inverter, even when charging one or two electric cars.
- Battery capacity – I would opt for a relatively large capacity. Without electric cars, I would aim for roughly three times the installed solar capacity—so, for 5 kWp of solar power, a battery capacity of about 15 kWh. This places less strain on the battery, meaning it doesn’t need to be replaced at 70% or 80% State of Health (SOH) but can continue operating for years down to 50% SOH. It also slightly boosts your self-sufficiency rate and further improves cost-effectiveness. A large battery allows you to stagger the timing of grid feed-in; this means that even with a 3 kW inverter, you can still feed the full surplus from a 5 kWp solar system into the grid. The prerequisite for this is a very large battery charged primarily via solar controllers (MPPTs) and only to a limited extent via micro-inverters.