Hello
we are planning a new semi-detached house.
We want to install a photovoltaic system later on.
We will get the right half shown in the photo. Orientation is southwest.
The photovoltaic system will of course be installed on the southwest side facing the garden.
The black area is the 3x5 m (10x16 ft) terrace, which will later be covered with a fixed terrace roof measuring 4 m (13 ft) deep and 5.5 m (18 ft) wide.
My question is whether it will still be possible to install a photovoltaic system on the roof once the fixed terrace roof is there?
If the terrace roof is on the southwest side in the garden, it will no longer be possible to set up scaffolding.
For maintenance or in case of problems, access to the photovoltaic system will be necessary later on (is access without scaffolding not possible?)
Or can the photovoltaic system be installed without scaffolding?
The house will have a gable roof and 2.5 full stories.
we are planning a new semi-detached house.
We want to install a photovoltaic system later on.
We will get the right half shown in the photo. Orientation is southwest.
The photovoltaic system will of course be installed on the southwest side facing the garden.
The black area is the 3x5 m (10x16 ft) terrace, which will later be covered with a fixed terrace roof measuring 4 m (13 ft) deep and 5.5 m (18 ft) wide.
My question is whether it will still be possible to install a photovoltaic system on the roof once the fixed terrace roof is there?
If the terrace roof is on the southwest side in the garden, it will no longer be possible to set up scaffolding.
For maintenance or in case of problems, access to the photovoltaic system will be necessary later on (is access without scaffolding not possible?)
Or can the photovoltaic system be installed without scaffolding?
The house will have a gable roof and 2.5 full stories.
Deliverer schrieb:
@Tom1978 If you can get below €250 per kWh, have three times more photovoltaic capacity than storage, and can more or less fully discharge the storage at night, it should be cost-effective.
A small addition to my earlier comment: Please be very, very cautious with cloud tariffs and research them beforehand. Most tariffs are already poor from the start. The main problem is that people often base their 20-year calculations on them. Currently, one of the largest providers is canceling all its “good” contracts, which is wrecking the calculations for thousands of customers who were previously sold outrageously expensive large storage systems as a condition of the cloud contracts...Reaching €250 per kWh will be difficult. The one I mentioned costs about €450 per kWh, and installation costs are additional. Where does the rule of three times photovoltaic to storage come from? Does it mean that if we install 13.29 kWp, the storage should not exceed 4.5 kWh?
D
Deliverer17 Sep 2021 09:02If you want to operate it economically, yes. Here’s a brief explanation again (there was already some practical input mentioned earlier):
For cost-effectiveness, you need many cycles (empty-full-empty). For that, you need two things:
1) A storage system that you can preferably empty every night throughout the year. Roughly, standby consumption multiplied by 12 hours equals the storage capacity.
2) A photovoltaic system that can recharge the storage as much as possible every day. Achieving this with a 1:1 ratio happens much less frequently than with a 3:1 ratio.
Personally, I would choose an even larger ratio (depending on roof area availability). Once two electric vehicles and a heat pump (both expected to be standard in 10 years) are drawing power from the photovoltaic system, only a small fraction remains for the storage. So: photovoltaic size matters!
For cost-effectiveness, you need many cycles (empty-full-empty). For that, you need two things:
1) A storage system that you can preferably empty every night throughout the year. Roughly, standby consumption multiplied by 12 hours equals the storage capacity.
2) A photovoltaic system that can recharge the storage as much as possible every day. Achieving this with a 1:1 ratio happens much less frequently than with a 3:1 ratio.
Personally, I would choose an even larger ratio (depending on roof area availability). Once two electric vehicles and a heat pump (both expected to be standard in 10 years) are drawing power from the photovoltaic system, only a small fraction remains for the storage. So: photovoltaic size matters!
Deliverer schrieb:
...
For cost-efficiency, you need many cycles (empty-full-empty). For that, you need two things:
1) A storage system that you can ideally empty during the night throughout the year. So roughly standby consumption times 12 hours = storage size.No!
It’s the other way around!
Once the system is purchased, usage should be minimized:
each cycle causes absolute wear and reduces the system’s lifespan.
Batteries provide more total energy over their operational lifetime if they are only discharged to half their depth of discharge!
Although a full cycle is proportionally more cost-effective in terms of resource use,
the total amount of energy delivered is absolutely lower compared to half cycles!
Hypothetical example:
with half cycles, a battery lasts 120 MWh, but with full cycles only 100 MWh.
It’s like with a car:
if I drive a lot—even unnecessary trips—the cost per kilometer goes down proportionally.
But in total, the investment costs are significantly higher.
Partial charging around the midpoint wins!
KingJulien17 Sep 2021 09:46Deliverer schrieb:
If I had written, "a photovoltaic system pays off in 8-18 years," would that have been better?Yes, for readers who haven’t looked into it closely, that would be clearer. The solar installer can still make the numbers look good.Deliverer schrieb:
Turnkey: That’s what I meant. If you build it yourself, the system pays off in two-thirds of the time.And how many percent of those wanting photovoltaics have the time and experience for that?Deliverer schrieb:
Standard size: A standard size system is one where all roof surfaces (house, garage, carport) are fully covered.I’m currently planning. If I cover everything, I get about 24 kWp on a fairly favorable roof. If you don’t make optimistic assumptions, without any feed-in tariff, you barely break even after about 20 years.
And that’s what’s always preached—that it only has to pay off through the feed-in tariff.
Just saying. You’re active in the photovoltaic forum, so you know your stuff.
That’s why you need to be more precise and not just flash the € signs at people.
D
Deliverer17 Sep 2021 10:14konibar schrieb:
no!
it’s the other way around!If someone deliberately chooses to buy a battery (for whatever reason), they should size it to maximize profit/minimize loss. You don’t buy a 40-ton truck if you only need to transport a single Euro pallet 100 km (62 miles) a day.Of course, I don’t want to encourage anyone to draw as much as possible from the battery, let alone charge an electric car with it. That would be nonsense in any case. It’s only about the unavoidable power consumption at night. That’s why I used the term “standby consumption.” Every unused kWh is a good kWh.
It’s true that batteries last longer if you don’t fully exploit their capacity. But this protection is already managed by the system itself. And if you oversize your battery by about 20%, that’s no problem. Since it’s usually the electronics that fail rather than the cells themselves, this is probably irrelevant anyway.
D
Deliverer17 Sep 2021 10:24KingJulien schrieb:
Yes, for readers who don’t look into it more deeply, that is true. The solar installer can also make the numbers look better. Ok.
KingJulien schrieb:
And how many percent of those who want photovoltaic systems have the time and experience? Very few. That’s why I didn’t write "payback after 6-7 years," but rather 11-12 years for turnkey systems.
KingJulien schrieb:
If you don’t polish the numbers, without energy consumption you might break even after about 20 years. And with energy consumption, it’s maybe around 11 to 12 years?!
KingJulien schrieb:
I’m just saying. You’re active in the photovoltaic forum, so you know your stuff. Recognized from the username?! It’s true, I’m interested and have spent a few weeks researching and have received a lot of help. Others can do that as well. How long do people usually research before buying a mid-range car?
(PS: I have already been warned twice (with a six-month delay) because I referred to a different site on the internet. Without a link. So you have to be careful.)
KingJulien schrieb:
and not blind people with the € signs. If it helps to encourage more people to use photovoltaic systems, I don’t mind. And in my opinion, I haven’t exaggerated... Anyone with a "normal" single-family house can manage that. Even currently. And hopefully it will look even better after the federal election.
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