Gas condensing boiler with external solar storage or integrated

Hello,

next week we have the construction meeting, a gas condensing boiler (we can choose the manufacturer) will be installed along with a solar system on the roof for hot water including a 300l storage tank.

Now we can also choose whether we want an external storage tank or a gas condensing boiler with an integrated storage tank, which is of course smaller (I think between 150-200l).

I would now like to hear your opinion on this; in my view, the advantage/disadvantage is the reduced space requirement. But what about maintenance if a component fails and is 150-200l sufficient (the plan is for a household of 4 people)?

Looking forward to your answers.

Layman's opinion: 150L for 4 people is not enough, or you would have to be very disciplined when showering/bathing. With solar support, larger storage tanks are usually advantageous because the heat is absorbed very locally (at noon) – but then not used. The remaining solar energy then dissipates. However, if you have 300L heated to 75 degrees, it keeps longer than just 150L. The problem with this is: if the sun does not shine, all 300L have to be heated by the gas condensing boiler. A good plan can determine the optimal heating system based on your needs.

Thank you already for your response. Are there any other opinions?

We are getting a gas-solar system from Wolf with an integrated 310l tank. Wolf seems to be of good quality.

I just saw that on their homepage, that would of course also be an idea! How is it in terms of space requirements, do you have an advantage through a "unit"?

I think it probably has a slight advantage due to the integrated storage. Unfortunately, I can't answer exactly how yet. Our heating will not be installed in the house until in 4-5.