ᐅ Heat pump combined with photovoltaic system

Hi,

last month we put a photovoltaic system without storage into operation.
Currently, we are not receiving any compensation because a bi-directional meter has not yet been installed. The current meter has a reverse current lock, so we are effectively giving away all excess electricity.

For the first 2-3 years after moving in, I had our heat pump set up to operate without an outdoor reset control and only respond to the outside temperature. Differences between day and night operation were not configured. This has been running more or less unchanged for about 7-8 years.

To avoid giving away electricity right now, I’ve been adjusting the heat pump settings over the past two weeks — shifting domestic hot water production more towards daytime and, through parallel shift, raising the heating curve during the day and lowering it at night. This initially caused it to become noticeably too warm in the evenings last week, in combination with the sun. So I lowered the curve during the day again. This morning it was a bit too cold. Nothing serious, but not as consistent as before.

How do you handle this?

Musketier schrieb:

How do you handle this?

Musketier schrieb:

Set up so that it worked without ERR and only based on the outside temperature.

That is perfectly fine for heating operation. I care more about comfort in the house than saving a few cents (which is not much anyway).

Musketier schrieb:

Hot water production mostly scheduled for daytime.

This way you can really take advantage of the sun. Thanks to working from home, I almost always control hot water manually when the sun is out (then you can nicely “play around” with when and at what temperature the heating is switched on). If it’s automatic because of appointments or business trips, then it runs during the daytime.

So you don’t make any distinction between day and night operation?

Tendentially, heating is significantly higher at night when temperatures are colder than during the day, if the target temperature is adjusted according to the outdoor temperature. I intended to compensate for this somewhat with the parallel offset. I probably shifted it a bit too much in both directions.

Musketier schrieb:

So, you don’t differentiate at all between daytime and nighttime operation?

Of course not.

Musketier schrieb:

Generally, heating demand is significantly higher at night when temperatures are colder,

In a new house, that only makes a marginal difference. At the moment, for example, the heat pump only starts to draw a bit more power during the late night/early morning hours (power consumption increases by about 100–150 watts). So, in my case, it’s not really worth implementing a nighttime setback. In the morning, my solar system (10 kWp) still doesn’t provide enough energy—especially in winter, when there’s usually little to no sun all day.

So, we are really talking about autumn and spring, when, for example, on a sunny day like today, the house and heat pump demand are only covered from about 9:30 a.m. onward. On cloudy days, it’s even later.

Before I start adjusting the system to save 500 watts or 1 kWh of electricity during the day (autumn/spring)—which translates to a 15-cent “gain” without considering the additional heating consumption caused by the nighttime setback, adding up to 7.86€ per season—I’d rather have a house that is heated precisely as needed.

You probably have a modern, variable-speed heat pump and, if I remember correctly, a very low energy consumption.

So far, I only had a standard submeter. Now, with a smart meter, it’s quite clear that the heat pump mainly operates at night.
I already planned to cover part of that with photovoltaic panels.
The technology has advanced quite a bit in the 12 years since we installed ours.
Mine always draws 2000 W (about 2.7 hp) when it starts up. Since the heat pump is a direct expansion type with a ground collector, it needs to switch off periodically and during regeneration, so it can’t run continuously.

Musketier schrieb:

You probably have a modern, modulating heat pump and also an extremely low consumption, if I remember correctly.

Until now, I only had a standard submeter. With the smart meter, you can clearly see that the heat pump mainly runs at night.
I already intended to cover part of that with photovoltaic.
The technology has advanced quite a bit in the 12 years since we installed it.
My unit draws about 2000 W when starting up. Since the heat pump is a direct expansion system with a ground collector, it apparently needs to switch off intermittently for regeneration and cannot run continuously.

Got it. I wasn’t considering that. For me, the heating runs at about 500 watts overnight around the freezing point at the moment.