Last September, we installed photovoltaic panels on our roof. We had plans for this for a couple years, but not the budget. After a bit more than a year, I wanted to write down a few numbers and thoughts for those who might be thinking about the same step.
I'm 100% aware of our own privileges. We are home owners and we've invested thousands of euros for our solar panels (see below). We are in difficult times and I'm more than thankful that we've been able to do this a year ago. Prices changed a lot since then. This article does not automatically assume at all that every home owner should be able to do the same.
- peak power: 6.72 kWp
- panels: 17 x 395 Wp
- battery: 7.7 kWh
- total price: € 17.400 (gross)
The plant isn't too big because we don't have more roof space. Our house faces south-east, which is also not entirely perfect but still more than good enough.
Stats for 2022
1.1.2022 - 16.11.2022
- generation: 7.32 MWh
- feed-in: 58% (4.26 MWh)
- self-consumption: 42% (3.06 MWh)
- autarky: 77%
- CO2 savings: 5 tons
- money saved: ~€ 1.100
- money earned: € 298
- from grid: 23%
- from battery: 35%
- from panels: 42%
The number here is fluctuating to say the least. We started with a consumption price of € 0.24 / kWh in January. It went to € 0.38 / kWh in July and reached € 0.54 / kWh just last months. There's this weird moment when we adjust the consumption price in the settings of our plant dashboard and suddenly the entire plant pays for itself in just 10 years instead of 15. But of course this is a very distorted way to look at it. Higher energy prices are not a source of happiness. We still have to get roughly 30% of our electricity from the grid througout the year. But our plant definitely feels like a protective layer.
This is maybe the most frustrating part. We get 0.07 € / kWh as feed-in compensation. I understand that power grid providers have to get their share for grid management. I don't expect to earn the same as we pay for electricity from the grid. But we produce roughly twice the energy we need and the gap between our consumption price and our feed-in compensation is just ridiculous.
Let's take a step back to the beginning. We knew for a while that we wanted to invest in solar panels. But during my research I found articles with the same concerns over and over. Is it really worth it? Do they actually pay for themselves? Is the yield high enough over the lifetime of the panels? How complex is the burocracy? There are gazillions of calculators to help you crunch the numbers. They can be helpful, but in hindsight it's also interesting how much doubt there is created beforehand – at least here in Germany.
I had the most helpful conversation with a neighbour who runs their plant for 25 years already. He told me about how well his panels still perform, how much this changed their energy bill and how positive this entire investment was for him over all those years. I can only recommend to talk to owners of plants – long-term owners if possible – if you have questions or doubts.
After scouting a few potential companies in our area, we finally settled for one that had the best combination of transparency in their offer and overall quality in communication.
I guess this is the part that can differ vastly, but we were super lucky with the entire installation process. It took one day for the team that installed the panels on the roof. Those guys were absolutely amazing. It took another day for a second team to handle all the installations in the basement (inverter, battery, etc.) The company also took care of the registration process and other paper work. It all went very smoothly.
The only exception was the power grid provider. They have to do a final inspection. We waited for them to come by for more than 3 months after the plant was already finished. This was super fustrating but neither in our hands or the hands of our PV partner.
We read beforehand that solar panels can improve the temperatures in the rooms under the roof. This summer was unfortunately a very good test phase for that. High temperatures are not great for the efficiency of solar panels. It's reduced to ~80% when it is too hot. Ideal is something around 20-25 degree celcius. But we found that there's indeed a noticable effect in our top floor office. Our panels are installed with a distance of roughly 10-15 centimeters above the roof tiles. There's plenty of air ventilation under the panels. The effect is quite obvious. The full heat of the sun is on the panels. They can get very hot. But the roof tiles stay at the regular temperature in the shade. That's quite a massive temperature difference. Although our roof is just 5 years old and insulated with the energy efficiency standard of a passive house, it seems like there's only so much it can do when there are more than 60 degrees on the roof tiles.
It is very hard to describe the feeling once it was all installed and running. There's this famous quote by Arthur C. Clarke:
Any sufficiently advanced technology is indistinguishable from magic.
It indeed feels like magic when our roof generates more than twice the electric energy our family needs throughout the year. I keep on opening the dashboard app with the stats over and over just to look at the numbers. It's maybe the most beautiful piece of technology I ever owned. I can't help but be happy and positive when I think about our little power plant. There's so much hope in this form of tech and in the energy revolution in general. There's a sense of freedom and security and possibilities. I look differently at solar plants and unused roof space. I wonder how there's still so much doubt and hesitation – especially among those who have the financial means.
I hope that we manage to create more excitement around the solutions to our energy consumption and emission problems.