Concentrated PV knowledge

We not only deliver the best PV quality, but also provide information about what moves us.
Here are all the interesting and important topics on the subject of photovoltaics.

Photovoltaic system


Photovoltaic modules form the actual "generator" for energy production.

"One photon releases one electron" - that's all you really need to know. The photovoltaically active material consists mainly of a monocrystalline silicon. The current itself is then collected via the smallest silver tracks on the silicon wafer and conducted to the inverter as direct current.

Most modules also offer very similar dimensions, as in Europe a closed glass surface of up to 2m² does not require a building application.

Glass-glass and glass-foil PV modules

PV modules are divided into glass-foil and glass-glass modules.

The structure of PV modules is always very similar: The front side consists of solar glass, behind which comes a transparent plastic film that embeds the silicon wafer. The silicon wafer is in turn protected from environmental influences by a black or white back foil. These modules are called glass-foil modules.

For particularly high requirements, an additional glass pane is placed behind the back foil in some modules. These are then called glass-glass modules. These are significantly more stable (snow load), more resistant to environmental influences (e.g. use in the vicinity of livestock farms) and are usually not considered a fire load, as glass-glass modules often meet the requirements for fire protection class A (e.g. at "property boundaries" between terraced houses).

Bi-facial factor

Furthermore, there are many modules with a so-called bifacial property. The term comes from the English: "bi-face" and freely translated means "two faces".

The energy of the sun's rays is "collected" on the front and back of the module. They are particularly effective when used with a solar fence or on ground-mounted PV systems. Sometimes, however, they are also found on roofs, especially in semi-transparent patio roofs.


In terms of dimensions, almost all modules currently on offer are very similar. In terms of appearance, however, there are very big differences.

Particularly for single-family homes, the aesthetically particularly appealing all-black modules are often chosen today. Here, not only the aluminium frame is anodised black, but also the rear foil is black. In combination with the black solar surfaces, there are no more white "lines and dots" in the module and the overall appearance of the photovoltaic system is very homogeneous.

The sometimes still discussed yield disadvantage due to higher heating in summer is almost negligible due to the already very close silicon surfaces. the additional black surface makes up only a fraction of the total surface.

The future: in-roof solution as tile replacement

A particularly aesthetic solution are the so-called "in-roof modules". These modules are installed directly on the rafter and batten construction of a roof as a replacement for conventional tiles.

These modules are not only much more inconspicuous and integrate almost perfectly into the roof, but also offer technical advantages. The significant weight savings compared to conventional clay tiles or concrete roof tiles make a photovoltaic system possible in some places due to the lower roof load. These modules, which are also available in terracotta, can also open up the possibility of installing photovoltaics at all in listed buildings ("invisible photovoltaics").

In the meantime, these "solar bars" are already very mature and offer almost the same power output with dimensions between 1.5 and 1.8m x approx. 0.35m and a weight of around 8kg! An example: a conventional module with 400 Wp and 1.75 x 1.13m dimensions offers an output of 202 Wp/m² - a "solar bar" with 1.8 x 0.35m is already at 200 Wp/m²!

We recommend this type of module as the future roof covering for new buildings or roof renovations! In the retrofitting of photovoltaic systems, conventional on-roof mounting is still the state of the art.


In addition to the modules, every photovoltaic system also needs an inverter. This is so called because it converts the direct current from the modules into the usable 230V alternating current.

If a battery storage system is desired, a hybrid inverter is usually provided nowadays. This can convert not only the direct current of the PV modules but also the direct current of the storage battery into alternating current. Since this avoids unnecessary converter losses, hybrid systems are the most efficient and attractive solutions today.

The inverter also often takes on the role of the "head". It collects all the values for PV power production and current household consumption with second-by-second precision and can thus control other components, such as the battery, wallbox or digitally controlled heating element, according to the available surplus.

Energy storage

If you want to achieve the highest possible degree of self-sufficiency with your photovoltaic system, i.e. become as independent of mains electricity as possible, supplement your photovoltaics with a battery storage system.

Our sales and planning staff will help you choose the right storage size. The recommended storage size depends on a number of factors: Total consumption + consumption behaviour of the residents + the size of the PV system + the other components, such as heat pump or electric vehicle.

So-called "lithium-ion batteries" are state of the art. This is a generic term and there are different chemical compositions. We exclusively use so-called lithium iron phosphate systems (LiFePo4), as these are the most reliable in terms of safety.

We installed our first lithium-ion battery storage system over 10 years ago. At that time, most people still used the very short-lived and vulnerable lead batteries. the Li-Ion battery from back then is still running today! ;-)

Emergency power and full backup solutions

All by itself, a photovoltaic system, even with a battery system, is not yet an emergency power solution! According to the current technical connection requirements, every generation system must switch off within a few milliseconds in the event of a power failure. This serves to protect e.g. grid fitters during transformer maintenance in the residential area or the fire brigade during fire-fighting operations.

Together with a battery system, however, a photovoltaic system can be expanded into a real emergency power solution in the event of a blackout. Only a few additional components are needed for this.

The so-called bypass emergency power is an entry-level solution. Here, in the event of a power failure and a charged battery, a separate single Schuko socket offers the possibility of supplying a small amount of 230V via distributors. This is an attractively priced solution.

The so-called full-backup solution, on the other hand, separates the entire household grid from the grid connection and sets up its own 3-phase synchronised sub-grid. Provided the battery is full, (almost) all electrical consumers in the house function as usual. With our modern systems, this switching takes less than 20 milliseconds and thus achieves the so-called UPS standard - an uninterruptible power supply. You won't even notice the lamps flickering in the event of a power failure! The good thing about these full-backup solutions is their "black start capability" - this guarantees that the batteries can be recharged the following day, even if the power is still out.


Charging solutions for electromobility

Your electric car can be charged directly with surplus solar power from your roof! The sun "flows" directly into the "tank" of your car! The necessary charging electronics ("wallboxes") for solar surplus charging are standard with us.

Charging with the power of the sun is not only ecologically valuable, but also makes economic sense. Between April and October, for example, it is possible to charge for around 2.50€/100km (based on 20 years of depreciation, 10 kWp-P, V20 kWh/100km average consumption).

In the near future, we will also be able to offer bidirectional charging. In this case, the storage unit of the e-vehicle can, for example, serve the consumption of the house during the night. Unfortunately, the technology and the approval of the grid operators are still missing.


We refer to all solutions that convert solar electricity into heat as "PV thermal". These are, for example, heat pumps for heating, so-called domestic hot water heat pumps for heating drinking water or solar-controlled heating gas in buffer tanks.

Depending on the existing heating installation and area of application, it is possible to achieve with current digitally controlled solutions that a gas boiler or fire boilers can be completely switched off from April to October.

We installed our first solar-controlled heating element more than 10 years ago - at that time we built it ourselves, as industrial solutions were not yet available.


Basics of Photovoltaics

From the sun to electricity.

The principle of photovoltaics is so unbeatably simple. No other power plant principle requires as little physics and technology as photovoltaics!

A short sentence describes the simplicity: "A photon releases an electron! That's it! 
In photovoltaics, nothing rotates, nothing moves, the physical active principle works without wear and tear!

An equally short sentence describes the necessary technology: "Five components and no knob!". That's it!
All you need are PV modules, the substructure, cables, an inverter and the feed-in point at the house connection. Everything works without external intervention: in the morning the system "wakes up" on its own and in the evening it also "goes to sleep" on its own.

Only with the addition of further Smart Energy components, such as a battery, wallbox, controlled heating rod or Smart Meter, does it become a little more complex. Here we offer many years of experience: we already installed our first "Smat-Energy systems" over 10 years ago!

Our services

All from one source

From the initial consultation to rooftop and electrical installation to grid registration, commissioning and customer service, we are at your service with our permanent staff.

These are TÜV-certified expert consultants for PV and storage technology, roofers, electricians and master electricians. And there are many student or graduate environmental engineers working in the planning office.

Customised solutions

We are manufacturer-independent!

We only offer you solutions that we trust and that fit you and your energy needs. You don't have to buy coupled electricity contracts or oversized battery systems. We would rather be happy to receive a recommendation after the joint project has been completed!

Customer service even after purchase

Even after the commissioning of your PV system, we are available to you at any time and with specialist know-how. A fixed component of our solutions is, for example, automated error reception. Here, your system is connected to our installer portal and we can react accordingly to error messages from your system (with the operator's consent).

Specialist craftsmen from your region

The market for renewables, especially photovoltaics, is very dynamic and in a state of flux.

Therefore, our own capacities are sometimes no longer sufficient and we resort to local craft partners for the installation. We deliberately do not say "sub-fitter", but partner - all our partners come from our region and are often known to you!