ᐅ Roof-mounted or integrated solar panels: which is better?

Hello everyone,

This year we are building our house and want to install a solar system to support the heating. We were recommended to use 6 collectors.

Now our question:
Which is better, rooftop or integrated (in-roof) installation? Are there differences in waterproofing or cost? Or is it the same, just a matter of aesthetics?

I would appreciate any information and thank you in advance.

Best regards,
Andre

andre02 schrieb:
Hello everyone,

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

Now our question:
Which is better, an on-roof or in-roof installation? Are there differences in watertightness or price? Or is it basically the same and only a matter of appearance?

I would appreciate any information and thank you in advance.

Regards, Andre

Hello Andre,

if I understand correctly, you are building your house new? In that case, I would recommend an in-roof installation for aesthetic reasons and because it should not cause any problems. It is important to have a so-called seamless underlay (bonded membrane) at least in the area of the collectors.

The on-roof option is more for renovations and less attractive. I don’t see any advantage to the on-roof solution for new constructions or complete roof replacements!

Kind regards

K.Brodbeck

Hello,

andre02 schrieb:
....Which is better, rooftop or in-roof installation? ..

Rooftop installation has the advantage that the collectors or modules are ventilated from behind. This can significantly reduce the building’s cooling load. For solar thermal systems, this is less significant compared to photovoltaic systems, due to the smaller surface area.

Best regards

€uro schrieb:
Hello,

A rooftop installation has the advantage that the collectors or modules are ventilated from behind. This can significantly reduce the cooling load of the building. For solar thermal systems, due to the smaller surface area, this is less important compared to photovoltaics.

Best regards.

Hello €uro,

I believe that a ventilated roof is already standard in new construction, isn’t it? At least, I have never planned a roof that was not ventilated.

I understand that the ventilation obviously needs to be greater than for a roof without collectors!

Best regards

K.Brodbeck

Hello,

K.Brodbeck schrieb:
...I think that ventilated roofs are already standard in new buildings, aren’t they? At least, I haven’t planned a roof that isn’t ventilated.

There are different roof constructions; ventilation is not necessarily mandatory in every case.
However, I meant ventilation above the outer roofing layer, usually roof tiles.
A cooling load calculation reveals quite a bit. As the heat transfer coefficient (Ht´) of the building decreases, the cooling load increases because buildings become “lighter.” This is especially problematic, for example, in 1.5-story constructions (passive house standard), depending on the airtightness of the construction. The roof’s share can be significant here.
While the outdoor temperature (OT) is used for heating load calculations, the surface temperature (solar radiation) is decisive for the cooling load. For example, the absorption factor of the roof covering significantly affects the summer indoor temperature in the attic. Insulation measures that help in winter have relatively little effect in summer!
During the summer heat period, the outdoor temperature might be about 35°C (95°F), but roof tiles can reach surface temperatures of up to 90°C (194°F). The unwanted and entirely inappropriate “heating element” created by this requires no further explanation.
For example, an elevated, preferably full-surface photovoltaic (PV) system shades the roof area, which would otherwise be heavily exposed to solar radiation. => Cooling effect! This could potentially eliminate the need for mechanical cooling.

K.Brodbeck schrieb:
...I understand that the ventilation needs to be larger when the roof has collectors than when it doesn’t!

Why?

Best regards

€uro schrieb:


Why?

Hello €uro,

Because the building-integrated solar collectors are thicker than the roof tiles, the cross-section of the ventilation gap becomes too small and no longer functions properly or at all.

Best regards

K.Brodbeck