Photovoltaics on the terrace roof - sensible?

We will eventually get a glass patio roof (facing south-southwest, little risk of shading). Now I'm wondering if it might make sense to use glass with photovoltaic modules instead of regular glass. Does anyone here have that? Is the technology mature enough that it is worthwhile and economical despite the unfavorable, flat angle (additional installation costs are low, anyway you need a patio roof...) I definitely want to have an empty conduit installed into the utility room in the basement, where the battery would be located.

Our idea was similar. However, it will now be a normal flat roof and modules may possibly be placed on it, which can probably be adjusted as needed. These roofs are offered here in Dresden, for example, by Solarwatt. We don't really like that you then practically have the patterns on your face or on the ground underneath, at least I don't imagine that to be very nice. Otherwise, we would probably have done it the same way for the reasons you mentioned.

First of all, I don’t have this. From my point of view, photovoltaics always bring something. How much and after what time is, in my opinion, less dependent on the installation angle than on the overall concept in which you integrate it. If you already have or will have photovoltaics, storage, etc. on or in the house and it doesn’t disturb aesthetically, why not get a few kWp out of there as well? I would shade a terrace on the south side anyway. Why not with photovoltaics?

I don’t exactly know what you mean, are you talking about semi-transparent panels, something like this?


Either way, your questions are quite easy to answer:

Does anyone here have that?

I certainly don’t.

Additional costs for installation are low if you need a patio roof anyway...

Don’t underestimate that. A standard roof is installed by the metalworker, or whoever, with standard materials. The person doing it usually does it often. That’s good, because they know what they’re doing.
A standard photovoltaic system is installed by the electrician with standard materials. The electrician usually does that often. That’s good, because they know what they’re doing.

Now, the roofer doesn’t do photovoltaic systems and the electrician doesn’t do roofing. And that’s where the not-to-be-underestimated problems come up, which either cost you poor quality or a higher price. Sometimes, not rarely, even both.

So if you don’t have a certified photovoltaic roof specialist or can’t do a lot yourself, expect a considerable additional effort.

Is the technology mature enough that it’s worthwhile and economical despite the unfavorable, flat angle?

Photovoltaic systems are basically quite mature. The modules and inverters keep improving, but the development curve (regarding efficiency) is not as steep as five to ten years ago.
A flat angle doesn’t affect the yield that much. It’s basically even better if the modules get as much sun as possible throughout the whole day.
But if you want a transparent panel instead of a normal one, you have to accept performance losses that are not insignificant.

There are several other arguments against your plan.
If you don’t plan a 100 m² string, then the area is quite small, which further raises the costs per kWp. On a bigger patio roof, you might get about 12 modules. That’s about 4.5 kWp with normal modules. Because of the transparency, you surely lose about 12%, so you end up at 4.0 kWp. But I assume that these modules lag somewhat behind normal ones and you won’t get more than 3 kWp on the roof.
Such a small system is hardly still economical. (*I have meanwhile found a transparent module on eBay. Nowhere else quickly. It costs 290 EUR with 260 heat pump – comparison normal modules available for: 200 EUR with 405 heat pump)

Cost comparison without installation and additional material:

Transparent (3.1 kWp): 12 modules = 3,500 EUR; inverter: 1,200 EUR = 4,700 EUR --> 1,516 EUR/kWp
Conventional (4.8 kWp): 12 modules = 2,400 EUR; inverter: 1,300 EUR = 3,700 EUR --> 770 EUR/kWp

Then there are the additional efforts in the transparent variant (see above). The costs will run away from you so quickly; transparent photovoltaics simply won’t pay off anymore.

All in all, one can say that transparent modules are, in most cases, an expensive gimmick. There are surely great application cases on a larger scale, but the profitability there also comes from the repetition factor.
In my opinion, there are three sensible solutions for you:

a.) You build yourself a nice roof and forego photovoltaics.
b.) You build a simple roof and put conventional photovoltaics on it.
c.) You invest in a not quite so economical art project.

_Searching the term _Transparent solar modules: pros and cons_ in a search engine is worthwhile._

If you are going to have photovoltaics, storage, etc. on or in the house anyway and it doesn't disturb aesthetically, why not get a few kWp out of there as well? I would shade a terrace on the south side anyway. Why not with photovoltaics.

Because you usually can't just expand like that. Additional modules have to be matched to the inverter or to the overall system. The project is its own system.

Really amazing your information including the cost calculation. It opened my eyes (and closed my wallet :-) )