Solar panel installation, flashed into roof or suspended over roof

sas

Looking at panels for my home. Roof not slated yet so I have options.

I am not convinced that the price difference between panels and tubes is reflected in the performance difference between them. Any of the suppliers I've challenged on this have been inclined to agree with me.

So I'm considering my installation detail. I'd prefer to install the panels with the slates so that they are part of the slating layer. It looks better and I believe it is a more durable option from a weather proofing point of view. Engineer then pointed out that any changes later will require that slate be removed e.g. to replace a panel. This is a fair point.

Are the brackets that support the panels above the slates as likely to require replacement at 20 - 25 years as the panels themselves? If so I'll stick to my original plan.

Thoughts?

Wolfhound14

Hi SAS,

I'm not sure what you mean by the following:
I am not convinced that the price difference between panels and tubes is reflected in the performance difference between them.

I thought the tubes performed better and were cheaper than the panels?
I think aesthetics are the main reason for chosing panels over tubes.

I am at a similar stage in my build. Hoping to start the roof next week. I am leaning towards the tubes, but it is a price and performance decision.
The probably don't look as good.

sas

Wolfhound14 wrote: »

Hi SAS,

I'm not sure what you mean by the following:
I am not convinced that the price difference between panels and tubes is reflected in the performance difference between them.

I thought the tubes performed better and were cheaper than the panels?
I think aesthetics are the main reason for chosing panels over tubes.

In general tubes are more expensive.

In general tubes perform better.

If tubes were cheaper I'd be buying them.

Wolfhound14

No seeing that here, maybe it depends on the supplies.

I have one guy quoting 4700 for system with Tubes and 5300 for same system with panels.
My plumber has agreed that this is normal.

sas

Wolfhound14 wrote: »

No seeing that here, maybe it depends on the supplies.

I have one guy quoting 4700 for system with Tubes and 5300 for same system with panels.
My plumber has agreed that this is normal.

Clearly our experiences are very different.

Please PM details of suppliers.

quentingargan

Tubes used to be more expensive than flatplate, but that has changed. To answer the original OP, personally, I would always prefer to see flatplates flashed into the roof properly. The wind load on a flatplate panel mounted above the slates, is very severe.

The only reason why you would mount a panel that way is because you are retrofitting and don't want to cut away the slates. On a new roof, you would always use roof integrated.

The main difference in performance between tubes and flatplate is insulation. The vacuum tubes lose less of the heat gained, so they are less affected by low air temperatures, and work better in cloudy conditions. Both will provide a similar amount of heat overall, but the tubes will provide it over a longer season.

The downside to tubes is that they are visually obtrusive, and they will lose their vacuum after about 20 years, requiring replacement. In that case, if you have used the twin-wall tubes or flasks, the replacements will be fairly cheap. Single glass tubes with integrated heat pipes will be more expensive to replace. Flatplates can be expected to last for 40 to 45 years, but of course, if they do break, it will be a bit of work.

Replacing any system requires scaffolding etc. I wouldn't choose on-roof panels just for that reason.