Photovoltaic system: Advantages and disadvantages, experiences, worthwhile?

Here are a few numbers:

Our photovoltaic system with 7.28 kWp is installed on a south-facing roof with a 5° deviation to the west. The roof pitch is very low at 20°, which is not optimal because especially in winter the sun shines at a flatter angle. However, in summer the irradiation angle reaches up to 90°, which is good.

The system has been running for less than a year, since November 2013. Since the end of January, a consumption meter (S0) has been installed so that the system can deliver more than 70% when consumption is good. The inverter is controlled via a Solarlog; overall, no more than 70% of the power may be fed in, but with higher consumption the system is regulated later, for example at 80%.

I have to say that classic consumers like dishwashers or washing machines, which could be started at noon, as well as stoves, are not very suitable to increase self-consumption, as these devices generate short consumption peaks that last only a few minutes. A better option is a continuous medium consumption, for example from a domestic hot water heat pump, electric car charging, or air conditioning over several hours.

The highest yield is between 11 a.m. and 2 p.m., here we regularly exceed 70%.

We currently cover about 60% of our consumption of 7 kWh per day with self-generated electricity and have to purchase 40%.
That is currently about 3 kWh of external electricity per day.
In winter, consumption is around 9 kWh daily and 80% external electricity.
Calculated over the year, it is 50/50.
Since November 2013, we have purchased exactly 1402 kWh of electricity. For a full year I expect a maximum of 1800 kWh. Our annual consumption in the last billing period was 3500 kWh including hot water preparation by instantaneous water heater for a single-family house with 200 sqm and 2 persons. Accordingly, we cover 50% of the demand with photovoltaics. By the way, I am at home all day.
Our self-consumption rate is only 15%, i.e., we feed in 85% of the electricity.
So far, since 11/13 we have fed in 3621 kWh and produced 4369 kWh (as of 07/01/2014).
We therefore expect at least 7200 kWh yield, which corresponds to about 1000 kWh/kWp. Currently, our Solarlog shows a value of 1042.8 kWh/kWp, but before the last three days of superb weather it was already 1061 kWh/kWp. The calculation was based on 950 kWh/kWp, so expectations have been exceeded.

We fully financed the system with 13,000 euros at 3.3% interest. A rate of 110 euros monthly, plus 50 euros (instead of previously 70 euros) advance payment to the electricity provider. We receive a feed-in tariff of 14.07 ct/kWh, a deduction of 54 euros net monthly, since the network operator only calculates with feed-in of 4600 kWh annually. This results in a substantial back payment on the feed-in tariff because we feed in significantly more (as of 7/1: 300 euros received but fed in for 523) as well as a back payment from the electricity provider, as the advance is calculated on a 2500 kWh annual consumption, while we will probably consume less than 1800 kWh.

Annual expenses (projected): 1320 euros for loan installments; the interest is tax-deductible; VAT for 7200 kWh: 192 euros.
Total: 1512 euros
Income: feed-in tariff for 6000 kWh: 844 euros, saved advance payment due to self-consumption at 1000 kWh: 250 euros, plus tax benefit for special depreciation and standard depreciation (5% per year), about 150 euros for us. Total 1244 euros.
Benefits: shopping at Metro saves quite a bit (example: crate of Coke 8.20 euros instead of 11.49 standard price at supermarket, which with 6 crates is over 200 euros per year).

Currently almost balanced, when the system is paid off in 10-12 years, it will generate real profit. Even more so, the higher the electricity price rises and the more self-consumption (planned are domestic hot water heat pump, split air conditioning unit, and electric car) is realized. Then it will already generate profit for us from next year.

Systems above 10 kWp from 8/1 onwards must pay the Renewable Energy Sources Act surcharge on self-consumption, so choose smaller or be faster.

: For completeness: Self-consumption is a sale from your company to you as a private person. Therefore, you have to pay VAT to the tax office for this transaction (self-consumption of electricity). After an income-expenditure statement (EÜR) is prepared, the revenues and expenses are offset against each other. That means you have revenues of €844 and expenses, e.g. interest expense, telephone, ... (including depreciation) of xx €. If you report a profit there, you pay taxes for the company. If you report a loss, you can claim a loss in your tax return. In 2013, our system produced significantly less than planned. In 2014, we are currently well above the calculated values. A bit annoying, but photovoltaic systems are dependent on the weather after all. The 70% rule (a maximum of 70% may be fed into the grid) can be regulated differently as well. We have a radio receiver from our grid operator. In case of overload of the power grid, the grid operator may completely shut down our system. For that, the grid operator must pay me a flat-rate compensation. This has never happened – we regularly feed in almost 100%.

I also considered it at the end of 2011. But regardless of the fact that it would no longer have been possible weather-wise, it wouldn't have been realistically worthwhile back then - from an economic point of view. If you have enough cash left over - maybe. But we didn't want to invest all the resources for it. With financing, the ROI shifts even further back. The matter might become interesting once affordable, reasonable storage technology is available to achieve the highest possible self-consumption rate. Best regards

About a year ago, we had a 7.28 kWp system installed on the roof and are very satisfied with it. Although the feed-in tariff is not spectacular (14.07 ct/kWh), we have already earned 821 euros and produced 6.9 MWh so far. Of that, 5.8 MWh was fed in. That is not yet optimal; we currently consume too little and still buy 50% additionally, but you become aware of it and automatically try to change that.

Our plans/implementation:

- Instead of a car, an electric vehicle was purchased. Or rather, "additionally". That was only a week ago, so I cannot provide long-term experiences yet, but the plan is to use this vehicle as the main car and the gas guzzler only for bulk shopping at [Metro] (see below). Charging during the day is not a problem since working hours are mostly at night/evening.
- Currently still hot water via instantaneous water heater. Overall electricity consumption for us is about 3000 kWh/year including hot water. The instantaneous water heaters are to be replaced by a domestic hot water heat pump, which will also be charged during the day by photovoltaics. Conversion planned soon (first a stable wall for mounting the device has to be made).
- Climate split unit instead of pellet heating/stove: especially in the transitional period, when the sun still shines well, heating can be done completely on self-consumption during the day with the climate split system. The device is available but will only be installed next week.

That means it will gradually switch to self-consumption. Then the photovoltaic system will really pay off, as heating and hot water with own electricity is significantly cheaper than with external electricity or fuels.
Also: [Metro]:
It is already worthwhile as a photovoltaic operator. No business registration is required for this. We buy cola crates there for 8.29 instead of 11.49 in retail. There are permanently 30-50% cheaper prices on Lindt chocolate. We also like to use that a lot. Often there are also promotions like currently 2 kg of Leerdamer slices for 5 euros. Or discount vouchers like 20% on technology. I bought our climate split device for 571 euros there instead of 699 euros (on the open market). That adds up.

Besides, one must not forget depreciation and special depreciation. For those who have not bought yet, you should definitely also look into the investment deduction! Unfortunately too late for us.
We completely financed the system externally and now pay 110 euros per month for a total amount of 13k euros including VAT at 3% at the [Ethikbank].

Edit: just noticed that I already replied to this thread, but ok, here are some more current numbers now.

Is now off-topic: what do you do with 2kg Leerdamer?

Food, if you are a cheese lover, don't worry, such an amount disappears with us long before the expiration date [MHD]