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Is my roof suitable for solar panels?

The optimal orientation for solar panels does not only have a south-facing roof. If the roofs face east and west, it can even be better. Almost all roofs are usable – including carports, facades or balconies, generally an off-grid solar system contains these important components, solar panels, solar generators, inverters, and other accessories, solar tiles and in-roof systems can also replace the roof covering. The most important information can be found in the article.

What is the optimal orientation for PV?

For a long time, a south-facing roof was considered the optimal orientation for a photovoltaic system. In principle, this is still the case: PV systems deliver the highest yields in the south. Towards the east or west, yields are about 18 to 24 percent lower.

Financially, however, east or west orientation can be just as attractive as south orientation! This is due to the falling feed-in tariff. Whether a solar system is worthwhile depends more and more on how much of the energy yield is consumed by the owners themselves. As a rule, the higher the self-consumption, the higher the profit.

Photovoltaic orientation to the east or west

Photovoltaic modules facing east or west cover self-consumption better: Most people are in the office or at work during the day, so their power consumption is low at midday. On the east and west roofs, the modules primarily generate electricity when the residents are still or back at home.

Another advantage: With an east-west orientation, you can cover both sides of the roof solar panels with modules and have more space available than with a south-facing system. That’s good, because PV operators have to fill their roofs!

Are north roofs suitable for photovoltaics?

Rather not. However, for optical reasons, the north roof is occasionally used for photovoltaics. Some owners find it better if all sides of the roof look the same. In most cases, however, photovoltaics are only installed on roofs that do not face north.

What is the optimal roof pitch for off grid solar systems?

The optimal inclination lies for south-facing roofs at 35 degrees and for roofs facing east or west at 25 degrees. In the east-west direction, the optimal angle is flatter because the sun is also flatter in the morning and evening than at noon. Overall, however, all pitched roofs with an inclination of 25 to 60 degrees are well suited for photovoltaics. The solar modules can be mounted on them parallel to the roof and they do not have to be set up. The steeper the roof, the easier it is for the rain to wash any dirt off the modules. And the sooner the snow slides off in winter.

Can I retrofit photovoltaics?

The later installation of solar modules is easily possible, for every conceivable roof construction. Photovoltaics can also be included in the planning for the construction of canopies. With modern glass-glass modules, the canopies can even be made semi-transparent. This airy architecture delivers light and electricity at the same time.

What is the best way to attach the solar modules?

Normally, solar modules are mounted on the roof covering. With pitched roofs, the installer screws special roof hooks into the wooden rafters under the tiles. The modules can be hung over the bricks and screwed onto aluminum rails. The solar modules are anchored on sloping aluminum frames on flat roofs. These are usually weighed down (ballasted) with stone slabs. The weight of the ballast stones must be supported by girders placed under the roof. Only in regions with strong winds are the frames anchored to the roof skin with bolts. This work must be carried out by professionals very carefully so that the roof does not leak later.

How much roof area do I need for photovoltaics?

A small solar panels with sixty cells (standard size) has an area of about 1.6 square meters and has an output of around 300 watts (some with over 100 cells even around 400 watts). 1 to 1.2 kilowatts therefore require around 6 to 6.4 square meters of roof area.

Between 850 and 1,300 kilowatt hours of solar power can be harvested per square meter of module area per year – depending on the region and orientation of the roofs (performance ration already taken into account). If the system produces less electricity, it was either planned incorrectly or it has a defect that reduces the yield.

Solar panels: weight per m2

Solar panel modules weigh around 10 to 15 kilograms per square meter, a single module weighs around 16 to 24 kilograms. Thin-film modules have the lowest weight. However, they also have a lower yield than standard modules.

The decisive factor for the statics is that the substructure of the roof has sufficient load-bearing capacity. It not only has to absorb the weight of the modules, but also additional loads from wind and snow. Such additional loads should not be underestimated, especially on flat roofs, where the solar modules are elevated and weighed down. Therefore, the photovoltaic planner should decide whether a structural engineer needs to check the roof.

Building-integrated photovoltaics: in-roof, roof tiles, facade

Conventional photovoltaic modules are mounted on aluminum frames above the roof cladding. Photovoltaic elements that are integrated directly into the roof or even into the facade offer completely new possibilities. An important criterion when buying, however, is the price: Building-integrated photovoltaics are not yet available in large mass production like conventional modules, which is why they are comparatively expensive. However, this may change as demand increases.

Photovoltaic roof tiles: costs and areas of application

Solar roof tiles became known through Tesla, but there are numerous solar panel manufacturers. Solar tiles serve as roof covering. Individual photovoltaic cells are either attached directly to conventional tiles or they completely cover the plastic roof tiles.

How much do these roof tiles from Tesla and Co cost? In the case of a photovoltaic system with solar tiles, the costs are about 30 to 50 percent higher than the standard version with modules if the costs for a conventional roof covering are deducted. On the other hand, it becomes even more expensive if it is not a new building or renovation, but the roof is to be re-covered especially for photovoltaics. Such work is not necessary for modules. Another disadvantage: Solar tiles need more plug connections, and troubleshooting can take longer if there are defects.

Because of the high costs, solar tiles are therefore suitable either for listed buildings or for new buildings and roof renovations if the owners* want to spend something on the appearance.

Solar roof without tiles: in-roof photovoltaics

In-roof solar modules are attached directly to the roof truss without being covered with roof tiles at this point. The in-roof modules are flush with the rest of the roof covering, which can look very elegant. A solar roof can also do without tiles.

There is now a large selection, so it is difficult to give general price information. However, the costs for in-roof photovoltaics are usually higher than those of conventional modules.

Can I mount photovoltaic modules on my facade?

Many designs also allow solar panels to be installed vertically. Photovoltaics on the facade only bring about 70 percent of the yield of solar modules that are aligned exactly to the sun. However, some advantages make up for this:

it is not uncommon for large areas to be available. Unshaded southern facades have a clear advantage here. Photovoltaics on facades also bring yields in winter, as the low position of the sun is better used. Solar facades remain snow-free. If you want to use as much solar power and 12v lithium battery as possible over the year, you should combine solar roofs and solar facades.

The disadvantage of solar facades, however, are the high costs. Because a type of safety glass is used, the costs for modules on facades are about twice as high as for roof modules. Photovoltaic facades are usually hung in front of the insulated building envelope. They have to be connected to the structure with metal bolts or supports. This must be done very carefully, otherwise thermal bridges can form.

Which roof shape is suitable for photovoltaics?

Almost all roof shapes and materials are suitable for classic photovoltaic modules:

pitched roofs or flat roofs,

tiled roofs,metal roofs,

hipped roofs or trapezoidal sheet metal,

Foil and bitumen membrane roofs.

The roofs can face south, west or east – for aesthetic reasons, some owners also cover north-facing roofs with photovoltaics.

Solar modules on a zinc sheet roof

Roofs made of smooth sheet steel, corrugated sheet metal or trapezoidal sheet metal require special substructures to hold solar modules and anchor them in the sheets. This is technically not a problem, but must be carried out very carefully during assembly. The most important thing here is the correct selection of the screws.

Solar system on a flat roof

On a flat roof, the solar modules must be set up or mounted on a stand to face the sun for optimal yield. Then they offer the wind a surface to attack, which may significantly increase the loads on the roof construction. Flat roofs should therefore be checked particularly well for their load-bearing reserves for photovoltaics. The planner takes care of this with a structural engineer if necessary.

Regardless of the roof type and surface, choosing a reliable service provider is half the deal whenever you decide to invest in solar energy. The leading California solar installers offer roof penetration warranties to cover any damage, so inquire if this is included in the package before you decide on a contractor. With complete coverage, you can rest assured that your roof will remain in perfect condition for years.

Fastening photovoltaics on a foil roof or bitumen roof

Very light flat roofs are usually covered with welded PVC foils or bitumen membranes. Normally, such roofs are not suitable for heavy loads such as solar modules with base. However, there are special mounting systems for foil roofs and bitumen roofs that can also be used for photovoltaics. For example, photovoltaic modules can be set up on bitumen with frames that are weighed down with stone slabs.

Can I use photovoltaics on my garage roof?

The effort to cover garage roofs with solar modules is usually less than on the sloping roof of the house. Up to an installation height of three meters, no scaffolding needs to be erected to install photovoltaics. On garages with a flat roof, the owners do not necessarily have to build a complete pitched roof on their garage. You can also anchor the modules to sloping metal frames.

Self-supporting carports can be retrofitted with photovoltaic roofs on airy substructures made of wood, steel or aluminium. As with the roofing of the terrace, the conservatory or the canopy, the solar panels used can be semi-transparent, i.e. partially translucent. But be careful: The regulations for overhead glazing also apply here.

What do I have to consider with solar systems on the carport?

Transparent or semi-transparent glass roofs for carports, shelters or conservatories are also called overhead glazing. This also includes transparent modules for photovoltaics, which are glazed on the back, so to speak, a solar glass roof. In the meantime, the first products are available on the market that have general building inspectorate approval. Solar modules are considered laminated safety glass (LSG) if they demonstrate certain properties.

How much electricity can a carport with a solar roof generate?

Only small photovoltaic systems with 2 or 3 kilowatts are feasible on a normal carport. More space is usually not available. But with that alone, between 2,000 and 3,000 kilowatt hours can be harvested per year. Such a photovoltaic system is inexpensive and can be installed and connected within a day.

What applies to carports or garages can be applied to all other extensions: sheds, workshops, offices or shops. And: A charging station for the electric car can be easily installed on the posts of the carport. The solar power is fed into the home network by the 3000 watt inverter. Generous solar roofs are conceivable, which combine the parking space for the vehicles with storage areas for bicycles (electric bicycles) or (electric) garden tools.

How does a balcony solar system work?

With balcony solar systems – also called plug-in solar power generator – tenants can generate their own solar power. To do this, they attach small modules, each with 300 watts, to the balcony parapet. According to the Rhineland-Palatinate Consumer Advice Centre, two modules can generate 540 kilowatt hours per year if they are optimally aligned to the south with a 30 degree inclination. A household can use around 400 kilowatt hours of this itself. In most cases, however, balcony modules are mounted vertically, so the yields are often lower.

The feed-in tariff is hardly worthwhile for such small modules. Excess electricity is therefore ultimately “given away” when it is fed into the grid. Due to the grid feed-in, the electricity meter must always have a backstop.

The cost of balcony solar systems is around 400 to 900 dollar. This also includes a power socket with installation by a qualified electrician. To be on the safe side, the electrician should also check the electrical installation of the apartment. This ensures that a suitable cable is used for the installation.

Can you set up photovoltaic modules in the garden?

Setting up photovoltaic modules in the garden is easy. If the sun changes position during the course of the day, however, they have to be moved manually on many properties, otherwise they will end up in the shade at some point. This variant is particularly suitable for plots of land and gardens,

which are only used in summer and

where little power is needed.

A microinverter is required in order to be able to use the electricity on site.

Solar patio roof: alternative to roof mounting

For which application is a solar patio roof suitable?

Solar terrace roofs make sense if the roof of the building is not suitable for a photovoltaic system due to the statics or due to excessive shading. The electricity generated can then be used or fed into the grid, and it is also possible to charge an e-car.

What is the structure that supports the solar system made of?

Mostly made of wood or aluminum. Wood has the advantage that it is robust and stable. However, you have to take care of it much more intensively to protect it from weather damage. Aluminum, on the other hand, is more weather-resistant, but also costs significantly more.

What needs to be considered with regard to security?

Stricter safety requirements apply to solar patio roofs than to solar systems on the roof of a house. The solar panels must be able to withstand much more wind pressure and also be able to cope with larger amounts of snow. To ensure this, the solar modules have special coatings (PVB – polyvinyl butyral).

Which terraces are suitable?

The terrace should face south and not be shaded. Even the smallest amount of shading can lead to a reduction in efficiency. The pitch of the roof is also relevant for the installation.

How much does a solar patio roof cost?

As a rule, costs of around $9,000 must be expected for a solar terrace with a 20 square meter terrace roof. Nevertheless, the high purchase price pays for itself in the long term through the electricity saved and its costs. As a rule, the investment has paid off after 15 to 20 years. Doesn’t a solar patio roof shade the entire patio? No, these roofs have a very high level of light transmission.



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