German forum about plant engineering for home: heating system, solar energy, etc ?

131 posts in this topic

17 minutes ago, Gambatte said:

@scook17

nice graph. But in the graph the X-axis should probably be kWp, not kWh.

Then doubling the Anlage size from 5 to 10kWp, ohne Akku, the share of on-site use drop from 29% to 17%, so the self use kWh increases actually very little. Make sense.

When I collected Akku quotes, altough I knew domestic Akku as small as 3kWh exists, the smallest I could get a quote for was 10kWh.

Not sure how much other families use, but we are 3 people, and we consume a total of 2500 kWh/yr (my wife works 100% from home, and I do 50%), 4700 kWh/yr seems excessive (yes I know the industry has financial incentives telling us we consume more than we do)

You can trust Fraunhofer, they have the correct units. And you do also. You generate based on your area and panel efficiency (kwp) but you use the energy or electricity, it is over time, so you use (kilo) watt-hours or kwh. If you are generating you need  time, area and kwp (simplified). When you are using, you can go over to kwh. As consumers, we mostly deal with kwh. If you compare to the cost of using energy from the grid, you have to use kwh. It just makes things easier to compare.

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21 minutes ago, scook17 said:

Seriously 10K. Does this include all the repairs and putting back everything in its place after they dig the trench?

 

I hope it includes absolutely everything including free heated pavements so you never have to shovel show again, but honestly I don't think we'll ever know, since the offer is so shite no-one is doing it.

 

In the early days, buildings were being joined for free, and that was fine (sadly not including anyone I know to ask about it) but now? 

 

21 minutes ago, scook17 said:

The fuel is basically free if they are burning the rubbish they collect, so why it should cost a lot I don't know.

 

Oh absolutely. That's what I said to the neighbour - Ok, 10 grand and then free heat forever? And he laughed extremely loudly :o and told me the rest, and we both laughed ourselves hoarse although it's really not funny. It must be costing a bomb to lay the pointless pipes.

 

19 minutes ago, mako1 said:

or in a locked cabinet that says, beware of the cheetah

 

 This ;)

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Why do people think that running a Fernwärme plant is free? There are tons of costs involved including employees, maintenance, etc. Is it free to get the rubbish to the plant and unload it? Lots of costs.

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The  important metric is if the cost to heat (including installation, usage €/kwh, O&M, environmental damage) is less than other sources. For new houses it is cheaper (and no stinky oil tank in the basement, no russian/US fracking/emirate gas). They don't do it because they have a digging fetish, it is more efficient. The only issue is in denser areas with older houses the cost of retrofitting. It actually is economically easier to swallow (or mandatory) in new buildings but they are often not as densely settled. What someone told Kiplette's neighbor was wrong.

Was kostet Fernwärme?

Die Fernwärmepreise fallen je nach Anbieter sehr unterschiedlich aus. Betreibt ein Anbieter mehrere Fernwärmenetze, so hat häufig sogar jedes Netzgebiet einen anderen Preis. Das kann sogar innerhalb derselben Stadt zu unterschiedlichen Preisen führen.
Fernwärmepreise setzen sich in der Regel aus diesen Bestandteilen zusammen: 

  • dem Arbeitspreis in Cent pro Kilowattstunde
  • dem Grundpreis pro Kilowatt angeschlossener Leistung (auch als „Anschlusswert“ oder „Leistungspreis“ bezeichnet)

Über den Arbeitspreis wird der tatsächliche Wärmeverbrauch abgerechnet. Der Grundpreis ist ein Fixpreis pro Jahr und beinhaltet die anteiligen Kosten an Kraftwerk und Netzen. Durchschnittlich macht der Grundpreis einen Anteil an den Gesamtkosten von etwa 25 Prozent aus, der Arbeitspreis ungefähr 75 Prozent. Ein durchschnittlicher Preis für Fernwärme liegt bei etwa 9 Cent pro Kilowattstunde, wobei der Grundpreis hier anteilig enthalten ist. Von diesem Durchschnittspreis gibt es allerdings deutliche Abweichungen nach oben und unten.

https://www.verbraucherzentrale.de/wissen/energie/heizen-und-warmwasser/fernwaerme-so-heizen-sie-weder-kosten-noch-klima-ein-34038

The trick is to find the sign about the cheetah and determine what the price actually is locally. But the price appears to be significantly less than gas/electro.

They will be requiring new houses to hook up if available (sewers also, it is really not that much of a burden). This can significantly improve the climate in cities (I still smell coal smoke in my neighborhood, even though the prices for apartments are obscene). It is unlikely they will force older houses to switch (Germany, do the wrong thing until forced to do otherwise) but they should. This will happen with incentives to get rid of your old system (or let economics and the high cost of gas and/or taxes convince people). One advantage is you are no longer burning anything in your basement or house. Air quality is actually  measurably worse when you cook with gas or have a gas hot water heater in your apartment. Only downside, no longer getting to pinch the chimney sweep for luck.

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2 hours ago, fraufruit said:

There are tons of costs involved including employees, maintenance, etc. Is it free to get the rubbish to the plant and unload it? Lots of costs.

 

 Yer, fair point. 

 

2 hours ago, mako1 said:

What someone told Kiplette's neighbor was wrong.

 

What we have to do is go on the website, make an appointment and get a personalised Angebot, which is what he did.

So theoretically what he was told was from the antelope's mouth, but I still wonder about the cheetah. It just doesn't make sense that it is continually so expensive. Maybe I'll make an enquiry myself and see where that goes.

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8 hours ago, mako1 said:

, they have the correct units. 

@Frantic

The units in the graph are wrong. Power is not measured in kWh, that's a unit of energy. I learnt enough physics to know this.

 

Either way, shall we agree not to argue on this?

All the best,

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In 2023 the system for Solar PV will change yet again to support a massive increase in generation from renewables:

https://www.bmwi.de/Redaktion/EN/Pressemitteilungen/2022/04/20220406-federal-minister-robert-habeck-says-easter-package-is-accelerator-for-renewable-energy.html

 

Actual details are here (in German):

https://www.bmwi.de/Redaktion/DE/Downloads/Energie/04_EEG_2023.pdf?__blob=publicationFile&v=8

 

Sorry, my German is not good enough to understand this well enough. But from what I can see, there seems to be an option to fully supply the grid. They will remove surcharges for self consumption of solar PV energy. This appears to be a different rate between self consumption and supply only. Seems also the rate paid for solar PV will be improved somewhat? 

 

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Abolishing the EEG-Umlage alone will make PV significantly more attractive. Long overdue step to be honest.

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1 hour ago, murphaph said:

Abolishing the EEG-Umlage alone will make PV significantly more attractive. Long overdue step to be honest.

What would make it even more attractive is allowing you to use the public grid as a battery. That´s how it´s done in Cyprus (where I´m living). What I don´t use myself, I feed into the public grid and get a credit of 1 kWh / 1 kWh I exported. I can import as many units almost for free (there is a net usage fee of €0.042/kWh) as I have exported. If Cyprus can do it, I don´t understand why Germany can´t.

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This seems like a useful arrangement. I had assumed that's how it worked until reading these threads, and am put off solar at the moment because it seems so complicated.

 

That can't be right for anyone.

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6 hours ago, jeba said:

What would make it even more attractive is allowing you to use the public grid as a battery. 

On 4/9/2022, 2:15:10, mako1 said:

 

@Frantic

The utility companies, or whoever, would still be in charge of maintaining the grid. After it got built in the first place.

Who repair it when it break? etcetera.

 

So the PV household like me and others, would have the luxury of free access to the battery, with none of the burden of looking after it. Sure it would be nice and I don't advocate against it.

 

But I do see some logic against it.

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Just now, kiplette said:

This seems like a useful arrangement. I had assumed that's how it worked until reading these threads, and am put off solar at the moment because it seems so complicated.

 

That can't be right for anyone.

Pity you are put off.

 

In reality it's not complicated. It's just us that make it look more complicated than it actually is.

Recently they even abolished income tax for ALL domestic PV. Which makes it both more attractive financially (just don't expect too much), and less complicated. 

You would be doing some good to the environment.

And playing statistics with your own PV-data is a lot of fun (that's how I concluded Akku are x10 overpriced).

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11 hours ago, Gambatte said:

Pity you are put off.

 

In reality it's not complicated. It's just us that make it look more complicated than it actually is.

Recently they even abolished income tax for ALL domestic PV. Which makes it both more attractive financially (just don't expect too much), and less complicated. 

You would be doing some good to the environment.

And playing statistics with your own PV-data is a lot of fun (that's how I concluded Akku are x10 overpriced).

Not all domestic PV. Only installations up to 10kWp can choose the "Liebhaberei" option and therefore opt out of paying income tax on any feed in tariff income they generate, if it is advantageous to them. Not everyone will choose this because it has some catches, depending on your circumstances, but the vast majority of people will certainly benefit from the income tax exemption.

 

https://www.pv-magazine.de/2021/12/23/freibrief-vom-finanzamt-steuererleichterungen-fuer-kleine-photovoltaik-anlagen-konkretisiert/

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31 minutes ago, murphaph said:

Not all domestic PV. Only installations up to 10kWp can choose the "Liebhaberei" option and therefore

That's exactly why I didn't write "all PV", but rather "all domestic PV"

Once again: on a purely financial point of view, opting for 10kWp is a very bad choice.

Anlage >10kWp are not "domestic" and attract a much lower fee-in tarif, ct/kWh.

And "Liebhaberei" existed well before the income tax for domestic PV was abolished.

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I can install 30kWp on my roofs. That's still "domestic PV" (there is no such legal definition by the way). Many people have more than 10kWp on their domestic roofs. I was simply correcting a piece of misinformation that could prove costly for someone who thinks "hey I don't need to declare my income from feed in".

 

Please stop repeating that anything over 10kWp is a "very bad choice" for everyone. It's simply not true because these things depend on several factors, such as roof orientation, solar irradiation, tax rate, cost paid per kWp of installed capacity and of course, the amount of energy you use yourself and how you use it. Have a heated swimming pool or air conditioning? Electric vehicle or three in the family? Heat pump? It's simply nonsense to draw an arbitrary boundary at 10kWp and claim that anyone building over that is making a "very bad choice". We use 7000kWh a year and that's mostly down to just a heat pump in a 212m² house. If we had that pool or ran air conditioning in summer or had an electric vehicle (we don't, yet) then our consumption could easily hit 10,000kWh.

 

There's also the real possibility that thanks to advances in battery design trickling through from the automotive sector, that you will sooner rather than later be able to retrofit your larger installation with batteries and then your self produced share goes way up. Adding a battery is trivial, getting back up on the roof and extending a system is not and all the initial costs are repeated.

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@murphaph

>10kWp is not a "very bad choice for everyone".

It is a very bad FINANCIAL choice for ALMOST everyone.

BTW, no matter the size of your PV, the amount of PV electricity going to your WP is anyway a very small fraction of the total WP consumption. Generally, when it's cold is also dark, and when it's sunny is also warm.

Please, do show us pic of your Tesla feet, your roof with 100 modules and 30kWp, and your heated swimming pool.

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You see you you are oversimplifying again. In summer I can run our heat pump in reverse, so it actively cools the house to a comfortable level.

 

In winter if you have an south facing roof and a very large installation, you can actually grab significant amounts of energy on cold, but sunny days and stuff that energy into the under floor heating concrete screed, which acts as a heat battery. The heat stuffed into the floor during the short days, provides heat later when it's dark. Ironically solar panels are more efficient in winter as they are kept cooler.

 

If you have a small installation you are very unlikely to be able to run your heat pump deep into the autumn but with a 30kWp installation you can drive the proportion of self consumed energy at the heat pump way up.

 

I have no electric car. I stated that quite clearly. I'm not sure you're reading my posts properly ;-) 

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@murphaph

Of the 6732 kWh produced by my PV (10kWp, 27modules, 13keur, and E- and W- orientation, 40grad), in the last 12yr, only 43kWh was produced in Dec 2021, so less than 1% of total. No much sun in December. And  of this 43kWh, 18kWh was sold to the grid, the rest used directly.

And of the 9900kWh gas we used that year to heat the house, 1606kWh was consumed in that very month.

Say we had WP instead of gas, and WP consumes a third the energy as gas does (btw is it a third or what?), so 535kWh. Our PV would have fed a massive 18kWh to our WP, so ca 3%.

This is exactly what I mean when I write that WP do not benefit very much from the PV. 

 

Fine with opinions. But please back them by data you measured.

33 minutes ago, murphaph said:

you can actually grab significant amounts of energy on cold, but sunny days

statements like this are not very quantitative. How much is "a significant amount"? 43kWh or 18kWh or what?

 

OK, I agree with your point about summer cooling (tough in my 9yr in Germany I have had maybe 2weeks/year that I desire cooling, I accept I am less bothered by heat than others).

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Ok, in your particular constellation you do not believe that a heat pump can contribute to a significant increase in the proportion of energy your PV produces. I'm ok believing that. Maybe you have an installation that is not well laid out to maximise the winter sun.

 

I wrote "can" because it all depends on how your system is built. We have a steep south facing roof. If you have an east-west roof then in winter you will never see much from the system because the sun is low on the horizon when it does come out. If you have a steep southern roof but there's a big tree in the way of the November/January sun, you're screwed. It totally depends on each installation how much energy it can produce and when. That steep southern roof is less efficient in summer when the sun is high in the sky and also doesn't benefit from early morning or mate evening sun like an east-west roof. I can't give you a kWh figure because every installation is different. There isn't even a percentage because in different regions it's cloudier than others in the winter!

 

The general consensus on the PV forum, where those people really know their stuff, is that given the right design and method of operation, you can significantly increase the amount of self produced energy consumed using a heat pump.

 

 

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Absolutely fine with having different opinion.

I do not "believe" things if I can measure them. And sure I do not believe the opposite of what I do measure.

 

If you had the opportunity to see measurement that led you to your opinion (ok, not measurement from you, bu still), please share them and we reconsider. Maybe I'm wrong.

But if you have not, the ONLY data you were presented (ok, my particular case) are mine, and they indicate the opposite of what you wrote. Yet you insist to "believe" the opposite, because "people there say so".

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