In the long run, your own solar power only costs a third of the electricity from the grid

Enpal offers a rental model for solar systems. Installation, maintenance, repairs and insurance are carried out by the company, the customer pays a rent and uses his own electricity. The advantage: the customer does not have to invest any money. But at first he hardly earns anything, after 20 years he takes over the system for one euro, then he uses his own electricity without having invested. We spoke to Benjamin Merle, Chief Product Officer at, about the possibilities of solar technology today – not just for a rental model.

Mr. Merle, at Enpal you don’t manufacture your own components, but you supply your customers with solar systems. What are the differences in quality on the market? Which quality features are important?

In the case of panels, the main thing is the energy density, which can be specified in watts per square meter or watts per panel. In addition, longevity is crucial – 25 to 30 years are realistic. This long service life should be secured by the manufacturer with an output guarantee of 20 to 25 years in order to protect it from degradation of the panels.

In other words, a strong decline in the performance of the panels.

Yes, the longer the output guarantee, the better. It is also important that there are now affordable PV optimizers on the market that ensure that electricity is still produced when there is partial shade. With inverters, it is important that the dimensions match the system and alignment exactly and thus get the most out of even with diffuse light. The inverter should come with an unlimited manufacturer’s guarantee of 10 years. With our rental model, we even guarantee our customers 20 years in which we will bear the costs for the replacement. In principle, we only work with tier 1 manufacturers – i.e. the direct manufacturers of the systems – to ensure all of this. Ultimately, sustainability is important. This is essentially about the possibility of integrating batteries, charging stations or other systems and making them jointly usable.

You should choose an open system that can be expanded with modules. Tier-1 is called the top level, i.e. directly from the manufacturer. As a private customer, I cannot buy there. Which countries do the individual modules come from?

When it comes to solar modules, we work with Longi in China, the largest PV manufacturer in the world. For inverters, we used to have devices from ABB. In the meantime, however, we have switched to Huawei because we have set up our own purchasing department in China. The power storage devices also come from Huawei. These are very high quality products at a reasonable price, and therefore the best for our customers.

I keep seeing advertisements for photovoltaic systems on Facebook and on the internet, most of which advertise supposed miracles in high-pitched tones. As a consumer, you are at a loss because you don’t know what’s behind it. How can you get smart?

There are many supposed expert blogs and advisors on the Internet, which unfortunately can raise even more questions with outdated data and information. Therefore, it is best to find out from the provider directly. Most of their websites already show some information. Many companies like us at offer non-binding consultations and planning, where you can get all your questions answered in a personal phone call.

We have seen a sharp drop in prices for photovoltaics. What dimensions are we talking about?

According to Fraunhofer ISE, the costs for PV systems in Germany have fallen by around 75 percent since 2006. So today we have a quarter of the prices of 2006. Therefore, your own solar system is the energy to participate today – clean, cheap energy from everyone, for everyone!

So the systems are much cheaper today. Is it now wiser to save money and buy a smaller and cheaper system or is it better to invest in more capacity in the face of falling prices?

It usually makes more sense to invest in more capacity. The same panels that used to produce 100 watts now produce 400 watts. You also need to think about the assembly costs. It is usually not economical to install only a quarter of the panels because they are more efficient today: Once the craftsman is on site, it is usually worthwhile to fully build the roof. And if you look into the future, you know: in a few years you will probably have an electric car and a heat pump. Therefore, he would do well to generate a lot of clean electricity himself on his own roof.

Due to the regulations, it is now more profitable to use the electricity you generate yourself instead of feeding the electricity into the grid. You need a battery storage for this, but they are also cheaper.

With an electric car in particular, a storage system can help to bring the self-sufficiency from normally 30 to 40 percent to the range of 60 to 80 percent. In the favorable case of 80 percent, you will then use almost exclusively your own electricity. This results in customers being independent and green while saving electricity costs. Depending on the system, we recommend storage between 5 and 10 kWh.

A power storage device of 10 kWh can deliver 1000 watts continuously for ten hours. Something like this costs around 6,000 euros today. The electricity is green and ecological and sustainable. But the question remains, what does this electricity really cost? You can only roughly answer that. But if you go over your thumb: How much does a kilowatt-hour from your own system cost with storage?

The electricity from your own photovoltaic system costs around 10-15 cents per kilowatt hour, depending on the set-up – compared to today’s electricity price of 30 cents.

So we’re talking about half or a third of the current electricity price. And that will continue to increase over the next 20 years. In 2010 it was around 23 cents, today it is over 30 cents. If you charge an e-car at a public charging station, up to 80 cents per kilowatt hour are due.

Right, the calculated price for your system will not increase, but the price for mains electricity will become more expensive. We’re talking about a lifespan of up to 30 years, maybe 35 years. So the scissors keep opening wider. You are not exaggerating when you say: In the long run, electricity from your own photovoltaics will cost a third of the electricity from the grid. For exact values, of course, you have to have a specific project calculated. A PV system is almost always worthwhile if the customer can use the electricity at home. In addition to the usual consumers in the household, there are also electric cars and heat pumps. And as you said, the price difference between your own solar power and that from a public charging station is enormous. Anyone who buys an e-car is forced to have their own photovoltaic system.