SmartGrid configuration, using photovoltaic surplus for heat pump

Hi,

Question about photovoltaic surplus. I have 16.4 kWp on the roof. And I have a SmartGrid heat pump running. The SG is activated on the heat pump via the potential-free contact on the inverter. Now I have to reconcile several values:

[*]Photovoltaic production to close the contact --> Start SmartGrid
[*]Photovoltaic production to open the contact --> End SmartGrid
[*]Kelvin by which the hot water temperature is raised
[*]Kelvin by which the temperature in the heating water buffer tank is raised
[*]Kelvin by which the room temperature is raised

The heat pump modulates between 1.5 and 4 kW. But only depending on demand, not on the available photovoltaic energy.

At which values would you close/open the potential-free contact, and by which values would you set the temperature increases?

A balance must be struck between

[*]using the photovoltaic power during the day so that no heating is needed at night
[*]not too high values, otherwise on cloudy days the heat pump will need power from the grid even during the day

What do you think?

How did you imagine the technical implementation and which values do you have available in which form? First you talk about "photovoltaic surplus," later it sounds a lot like a simple timer switch.

I read the feed-in meter and send the data onto the bus (KNX). If the feed-in >x then ON, if

 

The inverter has a potential-free output, with which SG+ at the heat pump is switched. Currently, SG turns "on" at 3.5 kW inverter power and off again at 2.5 kW. I know that my house consumes about 0.5 kW.

The heat pump has a timer: night setback for the heating circuit and night shutdown for hot water.
With SG+, the hot water is then increased by +5 Kelvin and the heating water buffer also by 5K.

Well, on the one hand, I consider the difference between 3.5 and 2.5kW too small to switch meaningfully (a few clouds might then lead to on-off-on-off, which heat pumps generally do not like due to minimum run times, switching lockouts, etc.). Secondly, 16kWp should practically deliver more than 3.5kW all day, so you barely have more than a day/night switching. And lastly, this has nothing to do with surplus, because if larger consumers are active, you might still have no surplus even at 3.5kW.

PS: I also consider the 5K increase for hot water to be too small to achieve a meaningful effect. I go from 42°C to 56°C, whereby the actual temperature is even lower due to the hot water lockout until 1 pm after the morning shower. However, this also depends on the storage size, habits, etc.

Hi,

thanks for your input, now we are in the discussion/support phase that I need.

I have measured: I have a base load of about 400W in the house. If a larger consumer is added, then accordingly more. These are cooking/baking, washing machine/dryer. Both take place in the afternoon hours, by then the heat pump should be finished. Possibly cooking in the morning, hence the 3.5 KW limit.

The smart meter must be in the consumption line so that the inverter knows how much surplus it is currently producing. The surplus it has goes to the car (if the heating is running, accordingly less goes to the car).