ᐅ Photovoltaic System: Costs and Savings Potential – Experiences?

They are very knowledgeable here. There are specific questionnaires and such for photovoltaic systems.

After submitting the VAT advance returns monthly during the first year, as any new business does, I was automatically switched to quarterly submissions the following year. I then informally applied to stop submitting advance returns altogether, and this request was approved.
At no point did I calculate the self-consumption monthly or pay VAT on it. These amounts are low, double-digit figures annually. No one pays any attention if you report it just once a year.
I don’t understand all the fuss around the taxes. However, due to previous self-employment, I do have some prior experience. Therefore, I also know that you can just talk to the people at the tax office, and they can be quite reasonable. There are possibilities that you won’t find on Google.

Hello everyone,

unfortunately, I’m not very experienced yet when it comes to photovoltaic systems. I wanted to start by looking into a cost-effectiveness calculation first...

For our planned new build, we are currently planning a ground source heat pump with a thermal energy output of 6,000 kWh for heating and 4,000 kWh for hot water. After some online research, I found that the electricity demand for this would be about 2,600 kWh per year. Additionally, we use around 3,000 kWh of general household electricity annually.

This brings me to a total energy demand of 5,600 kWh. For this, a system with 6.83 kWp would be required. According to online sources, the total costs including installation would be around 13,000 EUR.

If I include this amount in our mortgage loan for financing the new build, I calculate an additional monthly installment/repayment of about 40 EUR. On top of that, there is the basic fee for an electricity supply contract (which you need anyway, right?) of 15 EUR per month, as well as maintenance costs (repairs; replacement of wear parts; cleaning and insurance) of around 35 EUR monthly. Altogether, this adds up to a monthly cost of 90 EUR.

On the other hand, the usual electricity costs at 5,600 kWh x 28 cents/kWh plus a basic annual fee of 180 EUR come to 1,748 EUR per year, or about 146 EUR per month.

According to my calculation, this results in a saving of 56 EUR per month.

Is there no longer any government subsidy for photovoltaic systems? Tax benefits only apply to solar thermal collectors that provide hot water, right?

Are my considerations and rough calculations realistic and correct?

DaSch17 schrieb:



For our planned new build, a geothermal heat pump with a thermal output of 6,000 kWh for heating and 4,000 kWh for hot water is currently planned. After some research, I found that the annual electricity demand for this would be around 2,600 kWh. Additionally, we consume about 3,000 kWh of general electricity per year.

This results in a total energy demand of 5,600 kWh. For this, a system with 6.83 kWp would be required. According to online sources, total costs including installation should be around 13,000 EUR.



On the other hand, the usual electricity costs amount to 5,600 kWh x 0.28 EUR/kWh plus a base fee of 180 EUR per year = 1,748 EUR per year, or approximately 146 EUR per month.


Are my assumptions and calculations reasonably realistic and correct overall?

If you mainly need the electricity for heating and related uses between April and September (when about 80% of the total electricity consumption occurs), then go ahead. Otherwise, you will need a massive seasonal storage, or you will significantly oversize your system (by about 5 times), or you will buy a large portion of your electricity and lose much of your self-generated power if you cannot feed it into the grid.

Your assumption is wrong, the calculation is completely flawed and the system is way too expensive.

You won’t be able to manage without grid connection with any photovoltaic system in Germany.

Try combining self-consumption with feed-in tariff.

DaSch17 schrieb:

Hello everyone,

unfortunately, I am not very knowledgeable about the topic of photovoltaic systems yet. I wanted to start by getting a handle on a cost-effectiveness calculation...

For our planned new build, a ground source heat pump with a thermal energy output of 6,000 kWh for heating and 4,000 kWh for hot water is currently planned. After some research, I found that the electricity demand for this would be about 2,600 kWh per year. Additionally, we consume around 3,000 kWh of general electricity annually.

This adds up to a total energy requirement of 5,600 kWh. For this, a system with 6.83 kWp would be necessary. According to online sources, total costs including installation amount to around 13,000 EUR.

If I include this amount in our mortgage loan for financing the new build, it results in an additional monthly repayment/payment of about 40 EUR. Additionally, there is the basic fee for an energy supplier contract (which you still need, right?) of 15 EUR per month, as well as maintenance costs (repairs; replacement of wear parts; cleaning; and insurance) of around 35 EUR monthly. In total, that would be about 90 EUR per month.

On the other hand, the usual electricity costs of 5,600 kWh x 28 cents/kWh plus a basic annual fee of 180 EUR amount to 1,748 EUR per year or approximately 146 EUR per month.

According to my calculation, that results in a benefit of about 56 EUR per month.

There is no longer any government subsidy for photovoltaic systems, is there? Only solar thermal collectors used for hot water are still tax-advantaged, correct?

Are my assumptions and calculations roughly realistic or correct?

Complete nonsense.
That would mean you can heat your house in summer but have it nice and cold in winter.
If that’s how you want it, then go ahead...

DaSch17 schrieb:

Unfortunately, I am not very knowledgeable about photovoltaic systems yet. I just wanted to start by looking into an economic feasibility calculation...

Yes, it sounds like you’re not very familiar with photovoltaics yet, but that’s okay. Try experimenting with the usual online calculators.

DaSch17 schrieb:

Are my rough estimates and calculations realistic or correct?

Your rough calculations are not wrong but quite incomplete and therefore not realistic. You need to consider at least two more factors:

1. Your electricity consumption profile: When during the year do you use more electricity, and when does your photovoltaic system produce more? I have yet to see a household where electricity use is not clearly higher in winter than in summer. Conversely, the electricity production from a photovoltaic system is significantly higher in summer than in winter. As a result, you won’t be able to cover your electricity demand with solar power in winter and will have overproduction in summer. That leads us to

2. For any surplus electricity you feed into the grid, you receive a feed-in tariff of, say, 9 ct/kWh. So you will have income in summer.

The quote of 13,000 for a 6.83 kWp system seems high. What exactly is included? Others here in the forum have installed significantly larger systems for about the same price. Also, the electricity price including the meter seems somewhat high—especially since you can likely get a heat pump tariff for your heat pump, which would be beneficial.

What is certain is that a photovoltaic system is a very profitable investment in most cases.