Renew old heating with heat pump or gas boiler and domestic hot water heat pump

I don't know exactly where it is located. But heat pumps are relatively independent of location as long as the air can move freely. The temperature of the supply air doesn't differ as much as the temperature of surfaces.

When using excess electricity from photovoltaics, I don't need a second meter, right?

Which makes more sense, photovoltaics first or heat pump first?

Who connects the heat pump with the photovoltaics? The tradesman or the solar installer?

Many questions. I'll give it a try:


No. Only a bidirectional meter if you don’t already have one. But you don’t have to worry about that. As soon as your solar installer submits the request for your system and then reports the commissioning, they already know they have to come out. Important: neither you nor the solar installer should order the change. That is the duty of the metering point operator and it must not cost you anything. So be careful what you sign.


Doesn't matter. For photovoltaics, you should keep an eye on the current struggle over future feed-in tariffs. Relevant is the commissioning, i.e. the activation, which you and the electrician carry out together. But that should be clarified in the next few weeks, once the Federal Council and Parliament have agreed.


None. The systems have nothing to do with each other. There are control options, but they do more harm than good.


You yourself should learn to control your heat pump. Otherwise, nobody will do it because no one has the time. And you do it like this: in the transitional period, you heat from 9 a.m. to 5 p.m. That should get you through the night.
If that is no longer enough, you heat continuously for 24 hours and raise the temperature by 2 degrees between 10 a.m. and 4 p.m.

Hot water preferably only once a day around noon.

That’s the "coupling" of photovoltaics and heat pump done.

If done correctly and it works well, it can indeed be efficient. But according to Pareto, it's a lot of effort for little additional benefit.

Why:
First, you have to define what should actually happen when there is "too much" photovoltaics. Should the heat pump only run when the sun is shining? Probably not. Should it just make things a bit warmer? That also works with my suggestion. Should it produce hot water? That also works with my suggestion. Even better, because then it doesn't heat up three times by five degrees, but once by 15. That is better for the heat pump.

In the core winter, there is almost always too little photovoltaic power anyway. So you get the most out of it by increasing the power a little throughout the whole day and using part of it during the night. But caution is needed here too: efficiency suffers. The heat pump doesn't want to be "hotter than necessary occasionally." For me, after the "optimization" for photovoltaic, the coefficient of performance dropped by about 0.3 points. But the electricity is cheaper. You have to calculate.

The last point why controlling it is hardly worth it: the heat pump simply isn't a big consumer. Yes, it consumes a lot over time, but not much at once. It has to be pretty cold outside for a heat pump to draw over 1-2 kW. And if there are 10 kW available at that moment, it doesn't change anything about the heat pump. A car battery can then ramp up to e.g. 11 kW. But the heat pump, which should maybe make 2° more, only needs about 100 watts extra for that, which doesn’t make a significant difference.

So first K.I.S.S. and get to know the systems.
And if you are really into home automation, you can gladly do some programming around it. It is fun after all. But saving money is hardly possible.