taxation of own-generated solar electricity

156 posts in this topic

5 minutes ago, HH_Sailor said:

Following all these ideas and checking our personal pros & cons  as we are planning too 

You building a house? Ohi ohi, we built 2yr ago, it was a huge painful unnecessary nightmare. If you do, please don't use the same construction company as I did. The worstest company in the history of humanity.

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My conclusion is that a solar+heat pump is very attractive, but it becomes extremely attractive if you add a battery and 1 or 2 electric cars.

The battery enables all solar power.

EVs scale up the demand, to justify the investment.

 

As an example, 2 Evs self charged at home could save 2500€ per year in "fuel", compared to Diesel. This is before maintenance.

That's 25.000€ in 10 years! That alone might be enough to pay for the whole solar+battery system + extra cost of heatpump vs gas.

 

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I went back to my Excel.

Say in 2020 we had a 10kWh battery. Every day we would have loaded it the minimum between 10kWh, and the amount we fed into the grid.

And every day we would have used the battery, the minimum between the amount we actually took from the grid, and the amount that was stored into the battery.

Again: you need data on a daily basis.

So a 10kWh battery would have lowered our grid reliance by 963kWh. It would have also reduced our grid feed-in by the same amount. This is a yearly saving of 0.6*(0.3-0.1)*963:

0.6 is assuming 40% tax rate (yes, you pay tax on the self-use), 0.3ct/kWh and 0.1ct/kWh are Stromarbeitspreis and Einspeisungsvergutung.

So after tax a massive savings of 116 eur/yr.

 

The cost of a 10kWh battery is ca 10keur. Maybe add loan interest. Battery lifetime is typically 10yr if you read the warranty, or 20yr if you trust the vendor.

Is fitting a battery a good financial decision? Saving a "massive" 116eur/yr for 10-20yr vs upfront cost of "only" 10keur?

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When researching batteries today I found this:

https://www.muenchen.de/rathaus/Stadtverwaltung/Referat-fuer-Gesundheit-und-Umwelt/Klimaschutz_und_Energie/Energieeffizientes_Bauen/Foerderung_und_Qualitaet/FES/Foerderrichtlinie_2019/RiLi2019_Antragstellung.html

 

which links to this

 

https://www.bundesfinanzministerium.de/Content/DE/Gesetzestexte/Gesetze_Gesetzesvorhaben/Abteilungen/Abteilung_IV/19_Legislaturperiode/Gesetze_Verordnungen/2019-12-30-G-Umsetzung-Klimaschutzprogramm-Steuerrecht/3-Verkuendetes-Gesetz.pdf;jsessionid=F53837B5501EFB4F2220D2329B5412B8.delivery1-master?__blob=publicationFile&v=2

 

and also this

https://www.tesla.com/de_de/support/energy/powerwall/learn/incentives?redirect=no

Which is Germany wide.

 

First link is for Munich which gives (apparently) up to 4K off a battery storage/solar system.

 

Second lists the regulations (in German) for tax relief as the result of measure to improve energy efficency in a property which is older than 10 years and carried out by a trademan who can issue the relevant certificate to say it complies.

 

Bavaria sponsors Solar + Battery for 1500 Euros.

 

I could find no support for buying just a battery system.

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3 hours ago, Gambatte said:

@scook17, why do you have both gas and heatpump? I never heard of household having both. In fact, one of the benefit of heatpump should be that when building the house you save on the gas connection (>1keur), and you save on the yearly gas Grundgebuhr (another like 100eur/yr).

Because we were forced to have a heat pump as part of the planning. Gas connection was around 2K including internal plumbing and yes, yearly connection charge is 100 Euros or so. Well worth it IMHO. Alternative was a wood/electric heater or geo-thermal if you have lots of money to spend. I wanted options, and something I knew worked. Now we have a choice.

 

Heat pump had one unintended side effect. It doubles as an air conditioner in the summer, if you route the cold exhaust air into the house. You then get aircon for free. It's not very powerful, but drops the temps in the boiling summer months by 5C or so. Closing roller blinds helps a lot, but if it's 30C outside, it just seems to gets inside too, not matter what you do.

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3 hours ago, MikeMelga said:

My conclusion is that a solar+heat pump is very attractive, but it becomes extremely attractive if you add a battery and 1 or 2 electric cars.

The battery enables all solar power.

EVs scale up the demand, to justify the investment.

 

As an example, 2 Evs self charged at home could save 2500€ per year in "fuel", compared to Diesel. This is before maintenance.

That's 25.000€ in 10 years! That alone might be enough to pay for the whole solar+battery system + extra cost of heatpump vs gas.

 

Mike, given the link I just posted for Munich, 4K off the installation is a great deal. Unfortunately I live outside the city boundary, so I don't qualify.

 

As for electric cars, if you are a freelancer/self employed and buy a new electric company car, the amount you pay by the end of 6 years, is a fraction of the actual cost. You get a grant from the goverment for some amount up to 6K. Car tax is free for 10 years. Fuel, if generated with solar becomes effectively a fraction of the cost of petrol. Instead of 1% benefit in kind, you pay 0.25%. Car depreciates at 1/6th per year which is a tax right off, so depends on your tax rate as to the value of this. Insurance and Servicing is a tax deductable. MWST paid is an input tax deduction. More for employees, but employer can refuel the car free of tax as employee benefit. Ditto for electric bikes. Some of these incentives end sometime this year, but maybe replaced with others, who knows.

 

I was looking at the Telsa Model 3 or Polestar 2, but other ones people like include the V.W. ID3 and BMW 3 series. They are still not IMHO affordable without such incentives, but the range issues are now largely a thing of the past.

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6 hours ago, Gambatte said:

Used 2400kWh, as I wrote.

After all why does one install PV? To save money and environment? If so lowering consumption is a better measure in this direction.

 

Ah, the lowering the consumption argument which is not well thought through. If you use 10Kw or 100Kw and it comes from 100% green energy, who cares? I see this argument a lot in Germany. You need to save energy. No, you just need to generate energy in a better way.

 

Sure lowering consumption helps in other ways, like less transport, less materials etc, but it shifts the focus from where it should be, namely on how electricity is centrally generated. If it was 100% green energy at the plug socket, no one would care how much you used. The focus should be on getting it to 100%, not skimping and saving on the usage.

 

We opted for solar, but why isn't is compulsary in all new house builds? To get to net zero, every new house, or apartment block should be built with it, along with some storage option, either locally or centrally via the grid.

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5 minutes ago, scook17 said:

Ah, the lowering the consumption argument which is not well thought through. If you use 10Kw or 100Kw and it comes from 100% green energy, who cares? I see this argument a lot in Germany. You need to save energy. No, you just need to generate energy in a better way.

Are you really saying that to save the environment we shouldn't bother trying to consume less, rather is the energy companies that should give us green electricity?

 

5 minutes ago, scook17 said:

 If you use 10Kw or 100Kw and it comes from 100% green energy, who cares?

It doesn't come 100% green. That's why we care.

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1 hour ago, scook17 said:

First link is for Munich which gives (apparently) up to 4K off a battery storage/solar system.

In the UK the government introduced something called "help to buy". Housing was/is too expensive for many people, so rather than let it run its natural cost so it renormalizes to a sustainable value the taxpayer step in and guaranteed a chunk of the loan to the bank. The banks feel reassured and continue to hand out inflated loans.

Had this not put in place, is not that buyers would have not bought, is that vendors would have sold at the lower prices buyers could pay with the loans bank could give. So "help to buy" is a wrong term, better term would be "help to sell", even better term would have been "help to continue selling at artificially inflated prices".

 

Exactly the same as Baukindergeld. Should I be happy that I'm getting it, after all is "free", or should I worry that I'm paying for this "free" money via my own taxes?

 

Battery grant? Same. If the government gives a 4k grant, is not that consumers pay 4k less. Is that vendors profit 4k more, which comes from our taxes.

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22 minutes ago, Gambatte said:

Are you really saying that to save the environment we shouldn't bother trying to consume less, rather is the energy companies that should give us green electricity?

 

It doesn't come 100% green. That's why we care.

Realistically, today, we have to attack the problem by attacking both ends of the equation. We try to increase supply of green energy, but currently that can support no more than a peak of 50%, so the other 50% has to come from somewhere. So obviously you can reduce overall energy consumption to help meet available green capacity. However, sooner or later green energy will have near 100% or more of the needed capacity. Only problem is exaclty how many years are still to go before we get there...

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Some very interesting and thought provoking costings posted, so thank you to those who went into so much detail.  I was considering having a couple of panels for own use only (no feedback into the grid),  but from the figures above it will not save me a huge amount, and I would probably be better off with a single panel on the ground, and using it only for the washing machine and/or dishwasher. If I organised them to run only during the day when the sun is out it would probably be the most efficient way of doing things. 
Its not for now, but in a few years I can revisit the numbers.

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Susie, you are correct. More points:

*) it will not save you much money. At best, very little money.

*) If you still want to go ahead best you can do is to size your system matching your need. If your system is either too small or too little, you are not doing yourself a favour. Rule of thumb is your kWp to be your yearly kWh divided by 1000. So if you use say 3000kWh/yr, go for a 3kWp (btw 1 panel = ca 0.3kWp)

*) Other best thing to do is to to be smart with usage. Washing machine at 11am, roast at 12am, bake a cake at 1pm, dishwasher at 2pm. 

 

Again: I'm happy we discuss this here. But really the best place is this:

https://www.photovoltaikforum.com/

 

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12 minutes ago, SusieT said:

Some very interesting and thought provoking costings posted, so thank you to those who went into so much detail.  I was considering having a couple of panels for own use only (no feedback into the grid),  but from the figures above it will not save me a huge amount, and I would probably be better off with a single panel on the ground, and using it only for the washing machine and/or dishwasher. If I organised them to run only during the day when the sun is out it would probably be the most efficient way of doing things. 
Its not for now, but in a few years I can revisit the numbers.

 

Susie,

Washing machine and dishwasher use peak 2Kw. Mostly for the hot water I might add. If you ran it cold, then as an example the washing machine I have used up to 300w on spin, but around 60w on roll. Dishwasher uses around 45w when not heating or drying. A panel which is 1mx1.5m is typically 200w. They can be better, but a 'few' is usually not very much. We have 22 panels to generate a 5.72Kw system. You need a lot of space and the roof is typically not used, so it's free space.

 

So off grid system, you can buy a 'solar generator' which includes everything and you just plug in the panels and charge a battery. I am far from convinced they pay off with the current battery prices, or that the batteries will last. As more e-cars come on the market, battery prices will fall over time, a lot like panel costs have. 

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39 minutes ago, scook17 said:

As more e-cars come on the market, battery prices will fall over time, a lot like panel costs have. 

This is a very big point.

 

When I installed our PV I expected it was not going to be a smart choice financially (now that I have the data, I KNOW it was not a smart choice). My bet was/is, that battery prices drop enough to make it wortwhile fitting a battery (now I realized it's wishful thinking, they should drop very hugely, maybe it'll happen but unlikely...).

 

But let say you really want to get a battery, maybe because we all like cool toys. After all people even buy Tesla.:D

How did battery prices change in the last years? They dropped very much. Are you sure you want a batter today? Or can't you hold tight and wait a few years when they will be probably few 1000s cheaper...?

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5 hours ago, HH_Sailor said:

Hi @scook17

Are you talking about a standard water tank - as a lot of houses already have?

Or a large (  > 1000litr ) tank to act as a "battery" for your excess elec?

 

Following all these ideas and checking our personal pros & cons  as we are planning too 

Thanks!!

 

The formula is 

 

" Pt = (4.2 × L × T ) ÷ 3600. Pt is the power used to heat the water, in kWh. L is the number of liters of water that is being heated and T is the difference in temperature from what you started with, listed in degrees Celsius. "

 

So is your tank is 300L as our is, and I guess outside temp is 10C and I want 60C water, that a delta T of 50C. 

 

4.2 x 300L x 50C = 63,000 / 3600 = 17.5KwH

 

To get the time required to heat it, divide the result by the KWh of the heating element. Typically these are 2K to 3Kw, so that's 8 hrs with a 2Kw heating element.

 

You often don't empty the tank, so the delta is never really so high, as the new cold mixes with the hot. One solution I didn't see was to pre-heat the incoming cold water with waste heat, e.g. from drained shower water. I believe this is a heat recovery system, but it's something you should design in at the point to do the plumbing. Quite simple really. The waste water pipe passes through a tank before exiting to pre-heat the incoming cold water. The water never mixes, it's just a heat exchanger. This is all that is in the hot water tank, a simple copper spiral of pipe.

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26 minutes ago, scook17 said:

this is a heat recovery system, but it's something you should design in at the point to do the plumbing. Quite simple really. The waste water pipe passes through a tank before exiting to pre-heat the incoming cold water. The water never mixes, it's just a heat exchanger.

Cool. Sounds simple. But do these exist? I don't see why they shouldn't but I never heard of any...

any link...?

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47 minutes ago, Gambatte said:

Cool. Sounds simple. But do these exist? I don't see why they shouldn't but I never heard of any...

any link...?

Here is one I found online. Never used these, as I didn't know such things existed when all the plumbing went in.

https://phpionline.co.uk/feature-articles/waste-water-heat-recovery-wwhr/

https://powerpipehr.co.uk/price-and-size

https://www.youtube.com/watch?v=nyAoT9748lU

 

This works slightly differently. The waster shower water runs down the center pipe, around the edges. The cold inlet of the shower passes around the center pipe through the heat exchanger. Thus you add warmer water to the mixer in the shower. It claims 70% recovery, which is the max, if you have a very long, pipe run. Not cheap at £300 to £700 pounds from the UK.

 

I was thinking more of a DIY solution using and old hot water tank holding the cold water and running the waster shower water through the heating exchanging element. Ideally you'd get someone who manufactured such a thing and greatly increased the volume of copper piping as in the link above. In a cold water pre-tank you have much more volume so you don't even need copper.

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3 hours ago, Gambatte said:

I went back to my Excel.

Say in 2020 we had a 10kWh battery. Every day we would have loaded it the minimum between 10kWh, and the amount we fed into the grid.

And every day we would have used the battery, the minimum between the amount we actually took from the grid, and the amount that was stored into the battery.

Again: you need data on a daily basis.

So a 10kWh battery would have lowered our grid reliance by 963kWh. It would have also reduced our grid feed-in by the same amount. This is a yearly saving of 0.6*(0.3-0.1)*963:

0.6 is assuming 40% tax rate (yes, you pay tax on the self-use), 0.3ct/kWh and 0.1ct/kWh are Stromarbeitspreis and Einspeisungsvergutung.

So after tax a massive savings of 116 eur/yr.

 

The cost of a 10kWh battery is ca 10keur. Maybe add loan interest. Battery lifetime is typically 10yr if you read the warranty, or 20yr if you trust the vendor.

Is fitting a battery a good financial decision? Saving a "massive" 116eur/yr for 10-20yr vs upfront cost of "only" 10keur?

How did you reach the 964kWh value? At 80% daily usage, I would assume 2920kwh.

And is it really 40% tax? Isn't that on solar power, not on battery size?

Why do you need to subtract the Einspeisungsvergutung? And how does that relate with tax?

 

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3 hours ago, scook17 said:

I was looking at the Telsa Model 3 or Polestar 2, but other ones people like include the V.W. ID3 and BMW 3 series. They are still not IMHO affordable without such incentives, but the range issues are now largely a thing of the past.

BMW 3 series? AFAIK there is no such EV yet.

Choice depends on personal taste and intended use. For long trips, I would only accept a Tesla, not only because of range and autopilot, but mainly because of Supercharger network.

For city cars, anything goes.

 

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1 minute ago, MikeMelga said:

BMW 3 series? AFAIK there is no such EV yet.

Choice depends on personal taste and intended use. For long trips, I would only accept a Tesla, not only because of range and autopilot, but mainly because of Supercharger network.

For city cars, anything goes.

 

Sorry BMW i3

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