Solar on the roof? Your roof area must meet these requirements for photovoltaics

There is potential for optimization everywhere in companies: If employees need more knowledge, they can attend further training. If processes are not efficient enough, they are streamlined, for both time and cost reasons. However, most people are probably not aware yet that there is optimization potential hidden on Germany's commercial roofs. But we are.  

A solar system on the roof of your own company has numerous advantages: More stable and lower electricity prices in the long term, more independence from the energy market and ESG compliance – to name just a few. However, planning a photovoltaic system involves a few steps that should not be skipped on the way to ecofriendly green electricity. First and foremost, this concerns the question of whether the roof meets the requirements for a PV system. We have summarized the most important aspects for you. 

1. Is a roof renovation necessary beforehand? 

If you are planning to install a photovoltaic system on your roof, you should make sure that it will not require renovation for the next 15 to 20 years. Anything else would lead to higher and unnecessary costs, as the PV system would have to be dismantled and rebuilt accordingly. So, if your company roof is dilapidated, it should be renovated before a PV system is installed – for safety reasons alone, as the next point also shows.  

2. Have the roof statics been checked? 

Dead weight, wind, potential snow load in winter: A roof already must withstand a lot, even without a PV system. Before you start planning a photovoltaic system, you should therefore pay close attention to the roof statics and have them checked by experts. Otherwise, you run the risk of the roof's load-bearing capacity no longer being sufficient. Particularly with flat roofs, where the sloping racks in combination with the solar modules provide an additional surface for wind to attack, checking the statics is an essential prerequisite for photovoltaics. If you no longer have the necessary structural analysis documents at hand, you can request them from the building authority or the construction company responsible. 

3. Will a PV system work on my flat roof? 

Roof orientation and pitch have a direct influence on the energy yields of a photovoltaic system. Anyone who now thinks that only pitched roofs are suitable for solar systems due to the required inclination should not worry: On flat roofs, which probably make up the majority of industrial roofs, the solar modules can be positioned correctly for maximum yields using special mounting systems. This means that company roofs also meet the requirements for photovoltaics.  

Generally, the highest yields are achieved when the sun's rays hit the solar modules at a 90-degree angle. The ideal orientation for solar modules is 30 degrees to the south. However, modules facing west or east also produce good energy yields.  

4. Can shading occur? 

To generate the highest possible energy yields, solar modules should be free of any shading. Chimneys, aerials, trees, neighboring houses, or even other solar modules can cause shading if they are installed incorrectly and thus reduce the output of a photovoltaic system.  

Even if it is only a small shadow, it can make a big difference when projected: It is enough for the output of a single solar module to drop, for the output of the entire module string to be affected. You should also bear in mind that shadows change depending on the position of the sun, and therefore become larger or smaller. 

5. Is the roof size (and therefore the possible size of the PV system) sufficient? 

Have you calculated your electricity requirements or had them calculated? Then there is still the question of whether your roof area offers enough space for a photovoltaic system with the corresponding output. But even if your available (roof) area is too small, there is no need to fret: You can purchase the rest of the electricity you need via a power purchase agreement (PPA). 

Is your roof area "too" large? The quotation marks indicate that this is theoretically not possible. If you produce more electricity than you actually need with a solar system on your roof, you have two options: You can either feed the surplus electricity into the public grid and receive a feed-in tariff, or you can "store" it in an energy storage unit for use later. 

Note: To work with ENVIRIA, your project area should have a minimum size of 1,000 square meters.  

6. Is my roof covering an obstacle? 

This question is quickly answered: If, like many industrial roofs, your roof surface is covered with metal, bitumen, plastic or gravel, a photovoltaic system can be installed without any problems. Even areas with green roofs are no obstacle for a PV system. However, for insurance reasons, it should be noted that roof coverings such as bitumen or certain foils are flammable and safety precautions must be taken accordingly.