taxation of own-generated solar electricity

[MikeMelga 7,255]

6 minutes ago, scook17 said:

Sorry BMW i3

That's a terrible EV compared with any of the others. It's almost the same price as the cheapest Tesla (1000e difference), with 30% less range, no autopilot, etc. If you add the "mandatory" accessories, it becomes much more expensive than the Tesla. Remember the base Tesla is fully loaded.

[Gambatte 900]

1 hour ago, MikeMelga said:

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

As I explained before. With a hypothetical battery of capacity say 10kWh the additional daily Selbstnutzung would be the minimum between what I actually BOUGHT from the grid without having the battery on that particular day, and what was stored in the battery. And the amount I would have stored into the battery is the minimum between battery capacity 10kWh, and what I actually SOLD to the grid that particular day. Of course one needs electricity data on a daily basis, which I have. First gather the data for all 365 days. Then do the math for every day. Then sums up the outcome for all 365 days. Assumptions maybe okish but not as good as data measured on your own household.

Oh, you don't have data? Then you can listen to the vendors... I wonder if they are biased...  

 

1 hour ago, MikeMelga said:

And is it really 40% tax?

It is whatever rate you pay for marginal income tax. After all self-use of your own PV electricity counts like normal income. I put 40% just to put something.

 

1 hour ago, MikeMelga said:

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

Because out of the total kWh you PV produce, for every extra kWh that you use yourself, you sell one kWh less to the grid.

Again: it relates to tax because you pay tax on both: the photovoltaic electricity you sell to the grid, and also the photovoltaic electricity you "sell to yourself".

 

Using your own PV electricity yourself is of course better than selling it to the grid. But you also pay more tax on it. Still better than selling it to the grid, but not as good as it would be if there was no tax.

 

But come'on, go back to my numbers and put ZERO tax. This would improve from 0.6*(0.3-0.1)*964 to (0.3-0.1)*964, so 192eur/yr rather than 116eur/yr. Battery cost  is still 10keur... 

[MikeMelga 7,255]

On 2/12/2021, 5:15:56, Gambatte said:

As I explained before. With a hypothetical battery of capacity say 10kWh the additional daily Selbstnutzung would be the minimum between what I actually BOUGHT from the grid without having the battery on that particular day, and what was stored in the battery. And the amount I would have stored into the battery is the minimum between battery capacity 10kWh, and what I actually SOLD to the grid that particular day.

Feeling dumb today. Let's remove the grid from the equation. Let's assume you produce 80% of battery capacity every day (usually you should not use the full battery) and assuming there is no drop during winter. That's 2920kWh per year. You are showing 3x less. I'm sure I'm mssing something, but I can't understand it.

 

On 2/12/2021, 5:15:56, Gambatte said:

 

It is whatever rate you pay for marginal income tax. After all self-use of your own PV electricity counts like normal income. I put 40% just to put something.

Ok, but your effective tax is much lower AND you can deduct costs before taxes, right?

 

On 2/12/2021, 5:15:56, Gambatte said:

But come'on, go back to my numbers and put ZERO tax. This would improve from 0.6*(0.3-0.1)*964 to (0.3-0.1)*964, so 192eur/yr rather than 116eur/yr. Battery cost  is still 10keur... 

Let's assume 2920kWh (best case scenario for a 10kWh), assuming you can deduct costs and your effective tax is something around 25%. I don't still don't understand what the fuck the grid has to do with it, but I will keep the 0.3-0.1. That would give me around 600€ per year.

I'm definitely lost on this taxation weirdness, but I still can't understand why the 964kWh.

 

BTW, 10kWh is not enough for me, I would probably need 20kWh or more for my "dream house" situation.

[MikeMelga 7,255]

This page says:

Quote

You can also be exempt from all tax obligations . Namely, if you don't sell your electricity but only use it yourself. Your system is then your purely private matter. High self-consumption rates are also possible without battery storage if the photovoltaic system is small and can only cover a fraction of your electricity requirements. If you operate the system as an island system - i.e. without connecting it to the power grid - there is not even the option of selling electricity via the public grid.

https://www.finanztip.de/photovoltaik/pv-steuer/

 

I don't plan on selling it, so I would be exempt from it.

 

So let's do the math again. Let's assume I use 80% of the battery per day. That's 2920kWh x 0.3€ I save per year. That's 876€ per year of savings. The battery pays itself.

 

I am not a libertarian, but I have serious issues in understanding the logic behind taxing someone for self-production, if I don't intend to sell it!

[Gambatte 900]

Mike, you can make assumption because you have nothing better. You don't know how much every day your PV, the PV you never had, would produce. And you don't know how much of this production you would use before installing the battery. This is what I measured, no reason for me to make assumptions.

 

I'm sorry you don't understand. Here data taken right now from my Excel:

 

21st June 2020, the single day I sold most to the grid:

tot. consumption: 7.4kWh

self use: 5.1kWh

bought from the grid: 2.3 kWh

sold to the grid: 22.8 kWh

tot. production: 27.9 kWh

 

Say I had a battery that can take max 8kWh. How much was I going to effectively make use of it? In the battery I can store the minimum between battery capacity, 8kWh, and the amount I sold to the grid, 22.8 kWh. So 8kWh goes into the battery. And how much of this do I take out? Well, since I took from the grid 2.3kWh, I would have taken out 2.3kWh, no more because I didn't actually need more. Of course one could argue the leftover into the battery could be used the next day. Pity the next day the amount I took from the grid was only 1.5 kWh (and 1.3kWh the day after, and 2.2kWh the one after, and 1.5kWh the day after). So on this day the 8kWh battery increase my selfuse by 2.3kWh, despite the 8kWh capacity and the 28kWh production. Go ahead if you want the battery 20kWh instead.

 

And here data for one dark winter day I sold very little to the grid: 7th Dec 2020:

tot. consumption: 7.5kWh

self use: 0.5kWh

bought from the grid: 7.0 kWh

sold to the grid: 0.1 kWh

tot. production: 0.6 kWh

 

How much can go into the battery, the battery that can take 8kWh? Only 0.1 kWh, because out of the total 0.6 kWh the PV produced that day 0.5 kWh was used directly. So on this day the 8kWh-battery increases my selfuse by a "massive" 0.1kWh. You want a bigger battery?

 

I have the data for EVERY day. I sum up the outcome for every day and I obtain 964 kWh (I calculated 964kWh for a 10kWh battery, but in fact for 8kWh and 10kWh the outcome is identical, because there is not a single day that I sold to the grid more than 8kWh AND also bought from the grid more than 8kWh). And if the battery "size" is 4kWh, the extra yearly selfuse would be 920kWh. Again, extremely few days when I both sold AND bought more than 4kWh.

 

I am happy to pass my Excel data and equations to anyone interested. PM if you want it.

 

 

 

[Gambatte 900]

9 hours ago, MikeMelga said:

I don't plan on selling it, so I would be exempt from it.

Not becoming a PV business if you have a battery you would not pay tax on your self use, which is very little anyway with or without battery, but you also would lose out on the feed-in, which is very much. 

You would also not be able to deduct the purchase cost of the modules Wechselticther installation maintenance insurance bla bla, tot say 15keur.

That's why every PV-and-battery owner prefer to register as a business, because this way they know they are better off.

 

Imagine this: you run a restaurant. One day you decide to host the annual gathering of your tennis club at your restaurant. And you like your tennis friends so much, and are well off, and generous, that you decide you give FREE food to all. Everybody happy. Next day the taxman comes along unexpected and demands its share, for the food you gave them, although you didn't sell it. Unentgeltliche Wertabgabe.

Pissed off? Sure.

Are you saying you rather close down the restaurant and not sell any food to anyone, so you "save" the tax for the free food you gave to your mates? No, because you sell a lot to the paying customers, whereas you gave relatively very little for free to your friends. Same for photovoltaic.

[Gambatte 900]

Here we go. This plot shows in X the day of the year, in Y how much an 8kWh battery would have increased our PV-selfuse on that particular day.

The usefulness of the battery is maximum in spring and autumn, because both grid reliance AND feedin are somewhat significant in those days.

But it's also very poor in winter (because production is very little), and in summer (because grid reliance is very little).

The "usefulness" of the battery averages out at ca 3kWh/day, which is the 964kWh/yr I wrote earlier.

 

[MikeMelga 7,255]

1 hour ago, Gambatte said:

Mike, you can make assumption because you have nothing better. You don't know how much every day your PV, the PV you never had, would produce. And you don't know how much of this production you would use before installing the battery. This is what I measured, no reason for me to make assumptions.

 

I'm sorry you don't understand. Here data taken right now from my Excel:

 

21st June 2020, the single day I sold most to the grid:

tot. consumption: 7.4kWh

self use: 5.1kWh

bought from the grid: 2.3 kWh

sold to the grid: 22.8 kWh

tot. production: 27.9 kWh

 

Say I had a battery that can take max 8kWh. How much was I going to effectively make use of it? In the battery I can store the minimum between battery capacity, 8kWh, and the amount I sold to the grid, 22.8 kWh. So 8kWh goes into the battery. And how much of this do I take out? Well, since I took from the grid 2.3kWh, I would have taken out 2.3kWh, no more because I didn't actually need more. Of course one could argue the leftover into the battery could be used the next day. Pity the next day the amount I took from the grid was only 1.5 kWh (and 1.3kWh the day after, and 2.2kWh the one after, and 1.5kWh the day after). So on this day the 8kWh battery increase my selfuse by 2.3kWh, despite the 8kWh capacity and the 28kWh production. Go ahead if you want the battery 20kWh instead.

Thank you for the explanation. I understand your point. Maybe my idea on usage changes your math. My idea is to have 1 battery + 2 electric cars. If the Evs are stopped at home during the weekend, of course it's directly PV to cars. But during weekdays the scenario is they won't, because they won't be home during solar peak. My reasoning is that I need the battery to charge them at night, around 8-12kWh in total. So the battery would have 2 functions: one to stabilize consumption vs production during the day. And to charge the cars at night.

 

1 hour ago, Gambatte said:

 

And here data for one dark winter day I sold very little to the grid: 7th Dec 2020:

tot. consumption: 7.5kWh

self use: 0.5kWh

bought from the grid: 7.0 kWh

sold to the grid: 0.1 kWh

tot. production: 0.6 kWh

 

How much can go into the battery, the battery that can take 8kWh? Only 0.1 kWh, because out of the total 0.6 kWh the PV produced that day 0.5 kWh was used directly. So on this day the battery increase my selfuse by a massive 0.1kWh. You want a bigger battery?

Yes, it's definitely going to be bad in the winter, including the heat pump efficiency. I have no illusions there, although my "dream" house is in Portugal, not in Germany.

 

1 hour ago, Gambatte said:

 

I have the data for EVERY day. I sum up the outcome for every day and I obtain 964 kWh (I calculated 964kWh for a 10kWh battery, but in fact for 8kWh and 10kWh the outcome is identical, because there is not a single day that I sold to the grid more than 8kWh AND also bought from the grid more than 8kWh). And if the battery "size" is 4kWh, the extra yearly selfuse would be 920kWh. Again, extremely few days when I both sold and bought more than 4kWh.

I am happy to pass my Excel data and equations to anyone interested. PM if you want it.

Ok, I understood, the 964kWh is your production data, not the potential use of a 10kWh battery. In your case a much smaller battery would be a good fit.

[MikeMelga 7,255]

1 hour ago, Gambatte said:

I am happy to pass my Excel data and equations to anyone interested. PM if you want it.

Thanks, I want to simulate how much a battery + 2EVs would change this calculation. Some EV chargers can be programmed to optimized sunlight + home battery charge.

[Gambatte 900]

1 minute ago, MikeMelga said:

Ok, I understood, the 964kWh is your production data, not the potential use of a 10kWh battery. In your case a much smaller battery would be a good fit.

Nooooooooooo. 964kWh/yr would be the yearly increase of PV-selfuse given a 10kWh battery. My yearly production is a few MWh.

 

Sure, your EV would somewhat improve the situation, because unlike households they "use" your PV-production in summer and at night. Still useless in winter.

[Gambatte 900]

1 hour ago, MikeMelga said:

Thanks, I want to simulate how much a battery + 2EVs would change this calculation. Some EV chargers can be programmed to optimized sunlight + home battery charge.

Your challenge is that's you don't have (yet) exact data. This is exactly my strength for my conclusion that, for me, battery are x10 overpriced. I don't need to make any assumptions at all, I run calculations with my own data, my household, my panels.

My math can be done by any Schulkind. But the strength is not in the math, is in having the exact measured data that enables you to do the math for your specific case. And nobody without PV has these data. So you either listen to the vendors, or you listen to random strangers like me.

Anyway go ahead, I'm happy if I can help.

[Guest]

1 hour ago, Gambatte said:

Here we go. This plot shows in X the day of the year, in Y how much an 8kWh battery would have increased our PV-selfuse on that particular day.

The usefulness of the battery is maximum in spring and autumn, because both grid reliance AND feedin are somewhat significant in those days.

But it's also very poor in winter (because production is very little), and in summer (because grid reliance is very little).

The "usefulness" of the battery averages out at ca 3kWh/day, which is the 964kWh/yr I wrote earlier.

 

As the father of a young german girl, I didnt see that as a graph...   but if you turn it 90 clockwise, and join the dots, its a picture of character taking a piss off a wall!!!!

[Gambatte 900]

Mike, here for the file I sent you.

My data and model shows that adding an 8kWh Akku increase the PV selfuse by ca 930 kWh/year (not sure why I wrote 964 before, maybe a rounding mistake, whatever, sorry...). 

Adding an 8 kWh Akku and a car (car consumption 10 kWh/day), increase the PV selfuse by ca 1956 kWh/yr. Of course one can play with the numbers...I assume the car is away during the day, and evening it takes the minimum between its consumed 10kWh, and whatever is in the Akku on that day (max 8kWh, generally less).

Don't sum up 930 and 1956, 1956 is already the TOTAL increase, given both EV and Akku.

So 1956 kWh/yr is ca 700 eur/yr, an Akku costs 10keur and has a 10yr warranty.

Of course it's very possible that I made mistakes. I'm happy to discuss with anyone interested. 

 

Apologies the images are crappy, not sure why. I can email them if anyone interested.

[Gambatte 900]

Some more thoughts, no car this time round ...

 

You will NEVER make more than very little money with Photovoltaic.

 

PV vendor know that the drive to most PV-enthusiasts is saving money. Let's pretend that nobody cares at all about environment, no matter what they tell you, which is sadly almost true.

So you do your math and the vendors does it too. Say in 20yr you expect to use 24 keur of electricity, and adding a PV system of bla bla size would save you say 500 eur/yr, so a total of 10000 eur over 20yr. So you are happy to pay max 10keur for this PV system. Let's say you have some fear the PV maybe breaks down or whatever, so your max is 7keur, over this you conclude it does not make financial sense.

The vendor knows all this of course. Let's say they could sell you this system 2keur and be even. How much will they demand? Of course not 2k, otherwise zero profit. They could sell you for 3k, so 1k profit. But they know your argument that up until 7k you are still better off buying it than not buying it. So they will sell it for 6999eur. After all they know for you it's still a win, so why should you not buy it?

And what happens if you think about it for one year, then you approach the same vendor, meanwhile the production cost of Chinese PV panels dropped, but the price of German electricity went up? They know your math. Last year it was profitable for you to buy it at max 7k. Now German electricity costs more, so it's now profitable for you to buy it at say max 7.5k. The vendor knows all this so it will offer it to you at 6499, after all he knows for you it's still a win...

 

Of course this argument is far from perfect, too simplified. Both you and the 6999 vendor think that maybe a different vendor tomorrow will offer you the same system for 6998, etc, so the 6999 vendor is prepared to offer you maybe 6997... But still my conclusions are 1) costs of domestic photovoltaic is not very much lowered by a decrease in cost of manufacturing the PV., and 2) is very much driven by cost of you buying grid electricity, 3) your savings will be very modest at best.

 

I think the argument for Akku is different, because Akku prices will drop in near future by much more than the drop in photovoltaic cost.

And the Akku market is still in its infancy. We will see...

[MikeMelga 7,255]

Guys, I have to thank @Gambatte for the great Excel sheet he provided. I tried it for a while and my conclusions is that for my specific (future) case, with 2 Evs, potentially living in Portugal (more sunlight), the batteries pay off. This is because EVs charge mostly during the night.

I also think that companies will attempt to use your battery even if you dont consume enough. I've heard their plan is to feed extra energy to your batteries during off-peak and sell it to the grid on peaks. And of course, paying you a percentage in the process. Instead of you using the grid as a battery, it's the opposite.

[Gambatte 900]

Thanks for the mention.

14 minutes ago, MikeMelga said:

I also think that companies will attempt to use your battery even if you dont consume enough. I've heard their plan is to feed extra energy to your batteries during off-peak and sell it to the grid on peaks. And of course, paying you a percentage in the process. Instead of you using the grid as a battery, it's the opposite.

Yes, these "cloud speicher" are already now very aggressively marketed. They have their own very fancy ways to calculate costs etc. Unlike my models, it was difficult for me to conclude how much they are profitable or not. Plus, the tax system there is "extremely complicated", exact words from my tax expert. My gut feeling is/was right now they are still a rip off. In the next few years we will see...

 

[MikeMelga 7,255]

Yes, I think the whole sector is in dire need of disruption: simple solutions, clarity.

[HEM 11,080]

1 hour ago, MikeMelga said:

Yes, I think the whole sector is in dire need of disruption: simple solutions, clarity.

In Germany?  Forget it - they live from making simple things complicated (see the taxation system)...

[Gambatte 900]

2 hours ago, MikeMelga said:

 

2 hours ago, MikeMelga said:

 

On 12/02/2021, 13:54:27, scook17 said:

 

I would go as far as saying that cunny vendors deliberately make the market very murky so when they come along its easier for them to bullshit you and selling you massively overpriced stuff. Speaking with Photovoltaic Akku vendors that's been exactly my conclusion. 

 

[Guest]

on a serious note...  I have a appointment on Thursday with a "solar specialist"... Acording to the Door to door sales man... the there is no longer any tax implications on your "feed in "... tarrif