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

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Hi,

 

Anyone her knows a forum where to discuss topic like heating system for home, solar energy, etc ? Before asking for some quotes I would like to make an idea by asking people. People I know live unfortunaley live in flat or they did this kind of stuff 20 years ago or more.

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Sorry not 100% what you are asking, but a great forum on photovoltaic:

https://www.photovoltaikforum.com/

 

I actually dare saying very good chance you will find there nice and knowledgeable people willing to discuss other household energy stuff.

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Otherwise forums for Bauherren, there must be a few around, haven't checked for a while. Of course they're mainly for Bauherren, people building their brand new house, but probably still useful also for retrofit etc.

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Hi Gambatte, 

 

thanks for the link. What I would need is a forum where people share experiences and costs for changing heating systems (I am thinking to a hybrid gas+solarthermal).

Also PV systems is a topic that interests me.

 

The point is that I never did things like that till now (always lived in a flat as renter) and before going to ask offer to several company here in Munich I would like to have my own idea about this stuff.

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Frantic, just don't be afraid. Just go ahead and ask quotation.

The companies installing solarthermie are plumbers and also take care of heating. You can google it and find useful articles in "normal" media. Of course take all you read with a pinch of salt.

With solarthermie, you will need somewhere in you house/apartment sufficient space for a largeish warmwasser tank. I mention this because I know not every household has the space.

 

You never did this before. Well, unless this is your profession nobody does it twice in his life.

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12 hours ago, Gambatte said:

Frantic, just don't be afraid. Just go ahead and ask quotation.

 

It is not about being afraid. Before buying a thing or a service I tend always to try to be prepared and have an approximate idea of what i am buying and its price before starting the inquiry of the supplier or the shopping. :)

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@Franticvery good. But there's only so much random people around will know and can tell you. Did you get any good info from the other forums I suggested? 

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you might even find your various topics discussed here.  did you try the Search box?

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On 4.4.2022, 02:10:27, Frantic said:

hybrid gas+solarthermal

We switched to gas + heat pump followed by PV half a year later in 2021. I would be happy to share some info if you want to send me a PM. 

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Some observations which might help.

 

Solar PV generates lots of energy during the summer, but not much in winter. Percentage wise, 15% to 20% of peak summer, at best.

 

Panels can be arranged to maximize overall production, or to maximize production in winter. Prioritize winter if you want to use the energy yourself, as you will have far too much to use in summer anyway.

 

Had a solar thermal system in one rental house. It sucked. Would never do it again. Also once the hot water is heated, what can you then do with the energy? Solar PV is better in this respect as it's simpler and you can at least give (you get paid next to nothing now) away surplus energy to the grid.

 

Heat pumps work by temperature differential. So they suck out the heat from the air/ground. In winter they don't work so well, as in summer. Ground is supposedly better than air (we have an air one), but far more expensive and require digging, so not so useful for retrofitting as air systems. Heat pumps can work in reverse, very simply, so I converted ours to generate air conditioning in the summer. Thus we get hot water and cold air.

 

In winter we use gas for space and water heating. In spring-summer-autumn I switch over to the heat pump with gas backup for the hot water, but have no such option for space heating.

 

Main problem I have yet to solve is nothing was interconnected. So heat pump has fixed load. An old heating element connected to the solar would have been better, but at the time we were forced to have a 500w heat pump. So we waste 3+KW to the grid on a sunny period, when it could have been directed to heating the water. When cloudy we hardly get 500w, so draw power from the grid at expensive rates.

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Thanks to all.

Yes i searched here but not too much (apart that interesting long thread about PV) being this anyway a generalist forum.

 

@scook17 my situation is that I found a house I like and in case of purchase I will need to change the existing oil heating. My goal is to take advantage of the 40% BAF/BEG subisidies:10% for getting rid of the oil heating and 30% renewable energy solution. I am searching info for a good estimation in order to calibrate accordingly my offer. 

 

I discarded the heating pump for several reasons:

  • I don't want any noise generator in the garden
  • No floor heating but HeitzKorps (at least iron or steel, not cast irong). Almost class C energy efficiency (100 Kwh /m2*year), not optimal insulation for heat pump heating being the running temperature not high.
  • cost

 

I am keen to opt for gas + solar thermal. As far as I understood energy conversion factor for solar thermal is much bigger than the one that I will have with PV (that will be basically warming up water with an electric resistance powered by PV). Of course solar thermal is an "help" that will be minimal in winter.

My idea is to add in the future also a PV anlage just for the electricity but what makes me put it on hold now is the tax bureocracy. Ok, recently for analge till 10 KWhp (or 12 ?) no need anymore to pay taxes but it is not still clear to me if:

 

  1. I have to pay taxes on the quota i give back to the grid. This means that just what I consume is tax free. --> Steuerberater needed
  2. in any case (energy consumed or given to the grid) I have to handle the VAT in my Steuererklarung  --> Steuerberater needed

 

At the moment my personal situation is quite "simple" and I am able to do my Steuer erklarung by my self with the help of software but if I have to pay 600 euro to a Steuerberater for gaining the same amount (or even less) for energy sold to the grid then it makes no sense for me.

 

 

 

 

 

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I'm no expert, but am also going through the process of trying to change heat/power provision in my house, and have had a few folk over to advise. 

The best route (if you can get an appointment) would be an independent energy adviser. Verbraucherzentrale are offering subsidised house visits from an independent adviser (around here they only cost about 30 Euros if you can get them). Try your area here:  Beratung bei den Verbraucherzentralen | Verbraucherzentrale.de

Our local Kreis also offers a similar service, but again, they are currently not making new appointments due to high demand. You might be luckier where you live.

 

I'm considering a ground source heat pump, plus PV, plus a wood burning stove...and possibly a wind turbine. It's a big outlay, but with rampant inflation, if you have the cash it seems worth spending now. Also, last year we were without gas and electricity for a while due to local flood damage, so I'm trying to get something which would make us self-sufficient, and no single solution seems to offer that. I'll let you know costs, when the tradesmen finally get back to me!

 

I was also looking at pellet ovens, as you can use them for heating water and with your existing radiators but they seem to have really gone out of fashion. From folk I have spoken with, they are not an effort free solution, require two inspections per year, are at risk of suppliers (and maintenance, particularly software maintenance) disappearing, and are only really a "green" solution if the pellets are sourced locally from young rather than established trees.

I live in a log cabin/chalet so I don't want an electrician cutting slices out of my walls for cables, but assuming you have walls which can be replastered, it might be worth giving infra-red heating a look.

 

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@Frantic

I hear WP are very silent. I wonder if it is the gas heating lobby spreading the Idea they are noisy.

Yes of course, WP should have floor heating and good insulation. Actually you should first of all improve thermal insulation, before considering anything about heating, it's always the best thing to start with. Considering what type of heating comes later.

Disposing the old oil heating will cost extra of course, I read somewhere near 10k€, but you probably have no choice.

 

What I got my PV there were some burocracy. 

You can avoid Vat altogether, just opt for the tax status of Kleinunternehmer (you will be forced to choose, either Kleinunternehmer, KU, or Regelbesteuerung).

And since they changed the rule 1yr ago there is no more income tax on the PV. Neither the one you sell to the grid, nor the one you "sell to yourself".

If you're still put off by the tax headache, maybe do like me: hire a profi the 1st year only, and once you've learnt by following what this person does do it yourself. In any case the benefit of a good Steuerberater go beyond the PV only, you can easily get info worthed more than his/her Honorar.

Financially, PV pays itself off and generate a (small) profit. To optimize the return, apart from the obvious of going x the best of several quotation and optimize the usage (run oven, dishwasher, Waschmaschine, drier, whatever, when the sun shines rather than night), is to buy the size that matches your consumption: rule of thumb one kWp per ever 1000kWh of yearly consumption. I went very far from this rule and still make a profit.

 

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@dstanners

I don't think it's possible for you to be self sufficient.

I read domestic wind turbines are pretty useless because near houses etc the wind is hugely less than in open space.

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13 hours ago, Gambatte said:

@Frantic

I hear WP are very silent. I wonder if it is the gas heating lobby spreading the Idea they are noisy.

Yes of course, WP should have floor heating and good insulation. Actually you should first of all improve thermal insulation, before considering anything about heating, it's always the best thing to start with. Considering what type of heating comes later.

 

energy efficiency is 100,9 Kwh/m2*year. In class D for just 0.9. it is not that bad for being a 1994 detached house, at least comparing what  i was seeing in the last 2 years in the real estate market.

Additional thermal insulation is not an option because there are no funds and i will finance another debt on top of the mega mortgage.

It is just that, according to the law, I have to change the heating system. It is not that i want i am changing in order to optmizing. I have to. And from the moment I have to I am evaluating the best option with the current situation and the current government subsidies :)

Also the roof north-south oriented entice me :D 

 

 

Quote

 

 

What I got my PV there were some burocracy. 

You can avoid Vat altogether, just opt for the tax status of Kleinunternehmer (you will be forced to choose, either Kleinunternehmer, KU, or Regelbesteuerung).

And since they changed the rule 1yr ago there is no more income tax on the PV. Neither the one you sell to the grid, nor the one you "sell to yourself".

If you're still put off by the tax headache, maybe do like me: hire a profi the 1st year only, and once you've learnt by following what this person does do it yourself. In any case the benefit of a good Steuerberater go beyond the PV only, you can easily get info worthed more than his/her Honorar.

Financially, PV pays itself off and generate a (small) profit. To optimize the return, apart from the obvious of going x the best of several quotation and optimize the usage (run oven, dishwasher, Waschmaschine, drier, whatever, when the sun shines rather than night), is to buy the size that matches your consumption: rule of thumb one kWp per ever 1000kWh of yearly consumption. I went very far from this rule and still make a profit.

 

 

But if i make to the finanzamt this declarataion "i do this as hobby" in order to not pay income taxes(being still under 10 KWhp)  do I still need to declare myself as a kleinunternemen ?

By the way I am registered already as freiberufler Kleinunternehmer for a past free lance project i completed few years ago. Now I just keep putin 0 euro in the EüR declaration (I use smartsteuer for my steuererklarung).

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3 hours ago, Frantic said:

But if i make to the finanzamt this declarataion "i do this as hobby" in order to not pay income taxes(being still under 10 KWhp)  do I still need to declare myself as a kleinunternemen ?

On 4/5/2022, 10:16:36, Frantic said:

 

You MUST chose one of the two VAT categories: either Kleinunternehmer (KU), or Regelbesteuerung.

Income tax is a different thing: it has been abolished for every domestic PV, no matter what your VAT choice.

So if you opt for KU, from your PV you will never pay neither VAT nor income tax.

 

On the cost of insulation, I very strongly disagree. You say no fund. But if you borrow extra for it, it will pay off, in fact even including servicing the loan etc, it will be a much financial choice than NOT doing it. And the worse the current insulation (and it's very bad, you're telling us), the biggest the improvement (and the saving) for a given insulation investment.

If the house was already very well insulated, it wouldn't make much sense to invest extra to insulate it even better.

 

Good luck and keep us posted, I find it very interesting.:)

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is it basically a low end class C energy efficiency, is it really  very bad ? I thought it was not that bad.

West side and roof insulated, double glass windows.

By the way they accepted the offer (just via email but i asked for a more formal reservation document) so, unless they pull off from the deal, things starts to become real.

 

About the KU, i am already registered as freiberufler as IT Engineer. Shall I do a second parallel registration declaring another professional category ? 

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On 4/5/2022, 12:31:05, dstanners said:

 

I was also looking at pellet ovens, as you can use them for heating water and with your existing radiators but they seem to have really gone out of fashion. From folk I have spoken with, they are not an effort free solution, require two inspections per year, are at risk of suppliers (and maintenance, particularly software maintenance) disappearing, and are only really a "green" solution if the pellets are sourced locally from young rather than established trees.

 

 

I would avoid wood/pellet ovens, unless its just for supplementary heating.  The greenies are actually against wood ovens now that they make more pollution than expected (more harmful than car exhaust they say now!). It won't be long until they also re-think pellets!

 

https://www.green-zones.eu/en/blog-news/heating-with-wood-more-harmful-than-car-exhaust-fumes

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1 hour ago, Frantic said:

is it basically a low end class C energy efficiency, is it really  very bad ? I thought it was not that bad.

West side and roof insulated, double glass windows.

By the way they accepted the offer (just via email but i asked for a more formal reservation document) so, unless they pull off from the deal, things starts to become real.

 

About the KU, i am already registered as freiberufler as IT Engineer. Shall I do a second parallel registration declaring another professional category ? 

 

 

You can use this renovations calculator to get an idea of what changes will benefit you:

 

https://www.sanierungskonfigurator.de/start.php

The numbers match pretty much the values that a certificate would have. You can then compare the before and after renovation numbers. The estimated costs are way off, even it is just estimated from bare materials.

 

Although, I'm a little suspicious of the roof option - it doesn't seem to be registering my changes to it. 

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9 hours ago, Frantic said:

By the way they accepted the offer (just via email but i asked for a more formal reservation document) so, unless they pull off from the deal, things starts to become real.

Congratulations!

 

9 hours ago, Frantic said:

About the KU, i am already registered as freiberufler as IT Engineer. Shall I do a second parallel registration declaring another professional category ? 

Sorry, no idea.

 

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