Solar system on the roof or integrated into the roof, which is better?

Hello everyone,

this year we are building our house and want to install a solar system with heating support. We were recommended 6 collectors for this.

Now our question:
What is better, on-roof or in-roof installation? Are there differences in tightness or price? Or is it all the same and just a matter of appearance?

I would appreciate information and thank you in advance.

Best regards, Andre

Hello everyone,

we are building our house this year and want to install a solar system with heating support. We were recommended 6 collectors for this.

Now our question:
What is better, on-roof or in-roof installation? Are there differences in watertightness or price? Or is it all the same and just a matter of optics?

I would appreciate information and thank you in advance.

Regards, Andre

Hello Andre,

if I understand correctly, you are building your house new? Then I would recommend an in-roof installation for you, for aesthetic reasons and because it should not cause any problems. Important would be a so-called seamless underroof (glued membrane), at least in the area of the collectors.

The on-roof option is for renovation and less attractive. I do not see any advantage of the on-roof option for a new build or a complete roof renovation!

Kind regards

K.Brodbeck

Hello,

....What is better, on-roof or in-roof installation? ..

On-roof has the advantage that collectors or modules are ventilated from behind. This can significantly reduce the cooling load of the building at times. For solar thermal systems, due to the smaller area, this is not as significant compared to photovoltaics. Best regards

Hello,

Roof-mounted has the advantage that collectors or modules are ventilated from behind. This significantly reduces the cooling load of the building at times. With solar thermal systems, due to fewer m², this is not as significant compared to photovoltaics.


v.g.

Hello €uro,

I think that a ventilated roof is already standard in new construction, isn't it? At least, I have not planned a roof yet that is not ventilated from behind.

It is clear to me that the ventilation naturally has to be greater than with a roof without collectors!

Best regards

K.Brodbeck

Hello,

...I think that ventilated roofs are already standard in new buildings, aren’t they? At least I have not planned a roof yet that is not ventilated.

There are different roof constructions, and ventilation is not necessarily mandatory.
However, I meant ventilation above the final roof covering, usually roof tiles.
A cooling load calculation reveals quite a bit here. With decreasing Ht´ of the building, the cooling load increases, as buildings become ever "lighter." Particularly problematic, for example, in 1.5-story construction (PH), depending on AW construction. The share of the roof can be considerable here.
While the AT is used for dimensioning the heating load, the surface temperature (solar radiation) is decisive for the cooling load. For example, the absorption coefficient of the roof covering significantly determines the summer room temperature in the attic. Insulation measures that help in winter have relatively little effect in summer!
While the AT in the summer heat period may be around ~35°C, roof tiles can reach surface temperatures of up to 90°C. The unwanted and completely inappropriate "heating element" that arises here probably needs no further explanation.
For example, an elevated, as fully covered as possible photovoltaic system shades the roof surface, which would otherwise be heavily stressed by solar radiation. => Cooling effect! Possible renouncement of technical cooling.

...I understand that the ventilation must of course be larger than with a roof without collectors!

Why?

Regards

Why?

Hello €uro,

Because the in-roof collectors build up more than the tiles, thus the cross-section of the ventilation space becomes too small and no longer works or does not work well anymore.

Best regards

K.Brodbeck