ᐅ Photovoltaic Systems: Advantages, Disadvantages, Experiences, and Is It Worthwhile?

Here are some figures:

Our photovoltaic system has a capacity of 7.28 kWp and is installed on a south-facing roof with a 5° west deviation. The roof pitch is quite low at 20°, which is not ideal since the sun shines at a shallower angle in winter. However, in summer the solar incidence angle can reach up to 90°, which is good.

The system has been operating for less than a year, since November 2013. Since the end of January, a consumption meter (S0) has been installed to allow the system to deliver more than 70% when consumption is high. The inverter is controlled via a Solarlog; in total, no more than 70% of the capacity may be fed into the grid. However, during higher consumption, the system only reduces output later, for example at around 80%.

I should add that typical appliances such as dishwashers or washing machines, which can be run during midday, as well as electric cooktops, are not very effective for increasing self-consumption since they cause short consumption peaks that last only a few minutes. A more continuous moderate load, like a domestic hot water heat pump, electric vehicle charging, or an air conditioning unit running for several hours, is better.

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

Currently, with a daily consumption of about 7 kWh, we cover roughly 60% with self-generated electricity and need to buy about 40% from the grid. That amounts to around 3 kWh daily of external electricity. In winter, daily consumption increases to about 9 kWh, with 80% supplied by the grid. Averaged over the year, it’s about a 50/50 split.

Since November 2013, we have purchased exactly 1402 kWh from the grid. For a full year, I expect a maximum of 1800 kWh. Our total annual consumption last billing period was 3500 kWh, including hot water preparation via an instantaneous water heater, for a 200 sqm (2150 sq ft) single-family home with two people. This means our photovoltaic system covers around 50% of our demand. By the way, I am home all day.

Our self-consumption rate is currently 15%, meaning we feed 85% of our generated electricity into the grid. Since November 2013, we have fed in 3621 kWh and produced 4369 kWh (as of July 1, 2014). We therefore expect at least 7200 kWh total yield, which is about 1000 kWh per kWp. Our Solarlog currently shows 1042.8 kWh/kWp, but before three days of superb weather, it was already at 1061 kWh/kWp. The system was originally calculated for 950 kWh/kWp, so expectations have been exceeded.

We financed the system with 13,000 Euros at 3.3% interest. The monthly loan payment is 110 Euros, plus 50 Euros (previously 70 Euros) as an electricity bill prepayment. We receive a feed-in tariff of 14.07 euro cents per kWh, with a 54 Euro monthly reduction because the network operator only expects 4600 kWh annual feed-in. This results in a considerable settlement both in feed-in tariff payments, since we feed in significantly more (as of July 1: 300 Euros received for 523 kWh fed in), and in electricity bills, because the prepayment is based on a 2500 kWh annual consumption, while we will probably consume less than 1800 kWh.

Annual estimated expenses (projected): 1320 Euros for loan repayments; the interest is tax-deductible. VAT for 7200 kWh amounts to 192 Euros. Total: 1512 Euros. Income: feed-in tariff for 6000 kWh: 844 Euros; saved prepayment from self-consumption of 1000 kWh: 250 Euros; plus tax benefits from special depreciation and standard depreciation (5% per year), about 150 Euros for us. Total: 1244 Euros.

Additional benefits include shopping at Metro, which saves quite a bit (for example, a case of cola costs 8.20 Euros instead of the usual 11.49 Euros in supermarkets, saving over 200 Euros per year on just six cases).

Currently, costs and income almost balance out. Once the system is paid off, after 10-12 years, it will generate real profit. The higher the electricity prices rise and the more self-consumption is realized (planned with domestic hot water heat pump, split air conditioner, and electric car), the sooner it will generate profit. For us, it should start making a profit as early as next year.

Systems above 10 kWp installed after August 1 must pay the Renewable Energy Act surcharge on self-consumption, so choose a smaller system or act quickly.

@Elina:
For completeness: Self-consumption is essentially a sale from your business to yourself as a private individual. Therefore, you must pay value-added tax (VAT) on this transaction (self-consumed electricity) to the tax authorities.
Once a simplified profit and loss statement (EÜR) is prepared, income and expenses are compared. For example, you have income of €844 (approximately $870) and expenses such as interest costs, phone bills, etc. (including depreciation) totaling xx €. If you show a profit there, you pay taxes on the business income. If you show a loss, you can claim it in your personal tax return.

In 2013, our system produced significantly less than planned. In 2014, we are currently well above the estimated values. A bit unfortunate, but photovoltaic systems still depend on the weather.

The 70% rule (a maximum of 70% feed-in is allowed) can also be managed differently. We have a radio receiver from our grid operator. In case of grid overload, the operator is allowed to completely shut down our system. In return, the grid operator must pay me a flat-rate compensation.
This has never happened — we regularly feed in almost 100%.

At the end of 2011, I also considered it. But regardless of the fact that it would no longer have been possible due to weather conditions, it realistically would not have been worthwhile even "back then" from an economic standpoint.
If you have enough cash available – maybe. But we did not want to invest all our resources into it. With financing, the return on investment (ROI) moves even further into the future. The situation might become interesting once affordable, efficient storage technology is available to achieve the highest possible level of self-consumption.
Best regards

About a year ago, we had a 7.28 kWp system installed on our roof and we are very satisfied with it. The feed-in tariff isn’t amazing (14.07 ct/kWh), but so far we have already earned 821 euros with a production of 6.9 MWh. Out of that, 5.8 MWh has been fed into the grid. This isn’t yet ideal, as our consumption is still too low and we still buy about 50% from the grid, but it makes you more aware, and automatically encourages you to change that.

Our plans/implementation:

- Instead of a conventional car, we got an electric vehicle. Or rather, “in addition to” one. It’s only been a week, so I can’t share long-term experience yet, but the plan is to use this vehicle as the main car and keep the old gas/diesel car only for large shopping trips at Metro (see below). Charging during the day is not a problem, as work hours are mainly at night/evening.
- Currently, hot water is provided by an on-demand electric water heater. Our total electricity consumption is about 3000 kWh/year including hot water. The on-demand heaters will be replaced by a domestic hot water heat pump that will also charge during the day with photovoltaic energy. The switch is planned soon (first we need a stable wall to mount the device).
- Heat pump system instead of pellet stove/heater: especially during transitional seasons, when there is still plenty of sunlight, the heat pump can heat completely with self-consumption during the day. The unit is already available but will only be installed next week.

So, the transition to self-consumption is happening step by step. Then the photovoltaic system will truly pay off, as heating and hot water with self-generated electricity are significantly cheaper than using grid electricity or fuels.
Also: Metro:
It’s worth it for a photovoltaic system owner. You don’t need a business registration for it. We buy cases of cola there for 8.29 euros instead of 11.49 euros in retail. Lindt chocolates are 30–50% cheaper permanently, which we also like very much. There are often promotions, for example currently 2 kg of Leerdamer cheese slices for 5 euros. Or discount vouchers like 20% off electronics. That’s where I bought our heat pump system for 571 euros instead of 699 euros (market price). It adds up to quite a saving.

Additionally, don’t forget depreciation and special tax deductions. If you haven’t bought yet, you should definitely look into the investment deduction! Unfortunately, for us it came too late.
We completely financed the system with a loan and now pay 110 euros per month for a total of 13,000 euros including VAT at 3% interest with Ethikbank.

Edit: I just noticed that I already replied in this thread, but okay, here are some more current figures.

This is now off-topic: what do you do with 2kg (4.4 pounds) of Leerdamer?

Food, if you are a cheese lover, don’t worry, such an amount disappears at our place long before the expiry date.