Inverters

An inverter is an important element in a photovoltaic system. It takes on the central task of converting the direct current (DC) generated by the solar modules into grid-compliant alternating current (AC ) to convert.

How it works:

1. Direct current generation: Solar modules convert sunlight directly into direct current.
2. Conversion to alternating current: The inverter receives the direct current from the modules.
3. Conversion: Inside the inverter, the direct current is converted into alternating current.
4. Adaptation: The alternating current generated is adapted to the grid standards in terms of frequency and voltage.
5. Feed-in or self-consumption: The alternating current can now either be fed into the public power grid or used directly in the household.

Other functions:

In addition to converting direct current into alternating current, the inverter often takes on other tasks:

• Monitoring of the system: It collects data on the performance and efficiency of the solar modules.
• Protection functions: Both the modules and the power network are protected against overloads and short circuits.
• Optimization of performance: Modern inverters can optimize the performance of the solar modules, to maximize the yield.

Types of inverters:

There are different types of inverters, which differ in their functionality and application. The most common types are:

• Central inverter: A central inverter for the entire system.
• String inverter: An inverter for each string of solar modules.
• Micro inverter: An inverter for each individual solar module.

In summary, it can be said that the inverter is an indispensable element in a photovoltaic system. It ensures that the direct current generated by the solar modules is converted into usable alternating current, thus contributing to the efficient and safe use of solar energy.

The size of the inverter plays an important role in the efficiency and profitability of a photovoltaic system. If the inverter is too small, it cannot fully utilize the power of the solar modules Take advantage of it. However, if it is too big, unnecessary costs will arise.

Rule of thumb:

As a rough guide, the following rule of thumb applies:

Inverter power (kVA) ≈ 0.9 * system power (kWp)

Accordingly, for a 10 kWp system you need an inverter with approx. 9 kVA output.

Factors to consider:

However, the rule of thumb only offers a guideline. When specifically dimensioning the inverter, various factors must be taken into account:

• Module technology: Modern high-performance modules can deliver more power than their nominal power under certain conditions. This must be taken into account when designing the inverter.
• Shading: The performance of the solar modules can fluctuate due to trees, buildings or other objects. An inverter with sufficient power can do this Compensate for fluctuations.
• Orientation and inclination of the modules: The orientation and inclination of the modules influence the solar radiation and thus the performance of the system. This should also be considered when choosing the inverter be taken into account.
• Self-consumption share: If a high proportion of the solar-generated electricity is consumed by yourself, a smaller inverter may be sufficient.
• Temperature: The performance of solar modules decreases at high temperatures. High-quality inverters can partially compensate for this effect.

Oversizing:

A slight oversizing of the inverter is usually not a problem. It can even bring advantages, as the inverter can work under optimal conditions and extends its service life will.

Underdimensioning:

Underdimensioning the inverter, on the other hand, can lead to a loss of performance and even damage to the solar modules. Therefore, it is important to choose an inverter with sufficient power.

Expert advice:

The exact dimensioning of the inverter should be carried out by a specialist. He can take the individual conditions of the system into account and thus select the optimal inverter.

In summary, it can be said that the size of the inverter must be carefully tailored to the respective photovoltaic system. A rule of thumb can serve as a guide, but should not be the basis for the final decision.

The optimal placement of the inverter is an important factor for the efficiency and longevity of the photovoltaic system. Various aspects must be taken into account:

Ambient Conditions:

• Temperature: The inverter should be installed in a cool place. High temperatures can affect the performance of the device and shorten its lifespan. Therefore, avoid direct sunlight and hot roof spaces.
• Ventilation: The inverter must be sufficiently ventilated, to dissipate the resulting heat. An installation in a closed box without sufficient Air circulation is therefore not recommended.
• Moisture: The inverter should be protected from moisture and moisture. Outdoor installation is therefore only possible with a suitable housing.

Technical aspects:

• Cable length: The cables between the solar modules and the inverter should be as short as possible, in order to minimize power losses.
• Grid connection: The inverter should be installed close to the grid connection, to ensure short cable routes.
• Accessibility: The inverter should be easily accessible for maintenance and repairs.

Recommended locations:

• Garage: A garage usually offers good ambient conditions for the inverter. It is dry, cool and sufficiently ventilated.
• Basement: A basement can also be a suitable place for the inverter. However, make sure there is sufficient ventilation and avoid damp rooms.
• Outdoor shade area: If indoor installation is not possible, the inverter can also be mounted outdoors. Choose do this in a shady place and use a weatherproof housing.

Additional notes:

• Observe the manufacturer's safety regulations.
• Have the installation carried out by a specialist.
• Inform yourself about possible requirements for installing the inverter from your responsible authority.

In summary, the inverter should be installed in a cool, dry and well-ventilated place. The cable routes should be as short as possible and the power connection should be nearby. A weatherproof enclosure is required for outdoor installation. Have the installation carried out by a professional and follow the manufacturer's safety regulations.

The maximum distance between the inverter and the solar modules in a photovoltaic system depends on various factors, such as:

• Performance of the system: The greater the performance of the system, the shorter the cables between modules and inverter should be. Minimize voltage drops.
• Type of cables: The thickness and quality of the cables also play a role in the permitted length. High-quality cables with a larger cross-section can be used over longer distances .
• Type of laying: The cables can be laid on the roof, on the facade or inside the building. The type of laying influences also the permissible length.
• Manufacturer information: The manufacturers of inverters usually indicate the maximum cable length between modules and inverter in the technical data.

The rule of thumb is:

• Up to 50 kWp: The maximum distance should not exceed 50 meters.
• Up to 100 kWp: The maximum distance should not exceed 80 meters.
• Over 100 kWp: For systems over 100 kWp, an individual test by a specialist is required.

Please note:

• Voltage drops: Longer cables cause voltage drops. This can affect the performance of the solar modules and reduce the efficiency of the system. li>
• Losses: Long cables lead to higher losses. This can have a negative impact on the profitability of the photovoltaic system.
• Costs: Long cables are more expensive than short cables. The costs of the cables must be taken into account when planning the system. li>

Recommendation:

It is generally recommended to install the inverter as close as possible to the solar modules. This minimizes cable runs, voltage drops and losses, thereby increasing the efficiency and profitability of the photovoltaic system.

Special case: optimizer

When using optimizers on the module side, the distance between modules and inverter can be significantly greater. Optimizers regulate the voltage of each module individually, so that voltage drops occur on the DC side do not play a role. The permissible distance between modules and inverter in this case depends on the type of optimizer used and should be read in the manufacturer's documentation.

In summary, the maximum distance between the inverter and solar modules depends on various factors. It is generally recommended to install the inverter as close as possible to the modules. When using optimizers, the distance can be significantly larger

The maximum distance between the inverter of a photovoltaic system and the electricity meter is not legally required in Germany. However, the network operators have Their connection conditions usually set regulations for the maximum cable length between the generation system and the feed-in point. These regulations can vary from network operator to network operator, but are typically between 30 and 50 meters.

Reasons for the limitation:

• Voltage drop: Long cables cause voltage drops. This can affect the performance of the solar modules and reduce the efficiency of the system. li>
• Grid stability: In order to ensure the stability of the power grid, it is important that solar power is fed in within a defined voltage range takes place. Long cables can lead to fluctuations in the voltage.
• Technical requirements: The network operators have technical requirements for the feed-in devices, which may not be met by long cables.

Exceptions:

In some cases, the maximum cable length between the inverter and the electricity meter can be extended upon request from the network operator However, this is only possible if the technical requirements are met and no negative effects on the power grid are to be expected.

Recommendation:

It is generally recommended to install the inverter as close as possible to the electricity meter. This minimizes cable runs, voltage drops and technical problems and thus increases the efficiency and profitability of the photovoltaic system.

Additional information:

• The connection conditions of your network operator can be found on their website.
• When planning your photovoltaic system, you should seek advice from a expert. They can help you choose the right inverter and support the installation of the system.

In summary, it can be said that the maximum distance between the inverter and the electricity meter is not legally required in Germany, but is regulated by the network operators in their connection conditions. It is generally recommended to install the inverter as close to the electricity meter as possible.

This is in Germany in accordance with the VDE standards (VDE 0100-551 and VDE 0185) and the Energy Industry Act (EnWG ) mandatory.

Reasons for this regulation:

• Safety: Connecting an inverter to the power grid involves high voltages and currents. Therefore, it is important that This work must be carried out by a qualified person in order to avoid accidents and property damage.
• Expert knowledge: The correct connection of an inverter requires specialist knowledge of electrical engineering and the special features of photovoltaics. A specialist electrical company has this knowledge and can ensure that span> that the system functions safely and efficiently.
• Warranty: If the connection is professionally carried out by a specialist electrical company, there is a guarantee that the system complies with the applicable standards and regulations.

Consequences of non-compliance:

• Danger of accidents and property damage: Improper connection of the inverter can lead to accidents with electric shocks or fires. Property damage to the system or the power grid is also possible .
• Insurance loss: Many insurance policies exclude damage to photovoltaic systems that were not installed by a specialist company.
• Criminal charges: In the event of an accident or property damage, criminal charges may be filed against the operator of the system.

Recommendation:

Therefore, always commission a registered electrical contractor to connect your inverter. This is how you ensure. that the system functions safely and efficiently and that you retain all warranty claims.

In summary, it can be said that the connection of an inverter may only be carried out by a registered electrician. This is required for safety, professional knowledge and warranty reasons.

Choosing the right inverter is an important factor for the efficiency, profitability and safety of your photovoltaic system. There are various aspects, What you should consider when choosing an inverter:

1. Performance: The performance of the inverter must correspond to the total performance of the solar modules. It is better. to make the inverter slightly smaller.

2. Technology: There are different types of inverters, which differ in their functionality and characteristics. The most common types are:

• Central inverter: A central inverter for the entire system.
• String inverter: An inverter for each string of solar modules.
• Micro inverter: An inverter for each individual solar module.

3. Feed-in management: Modern inverters have integrated feed-in management, which regulates the feeding of solar power into the power grid. This is important, to meet the network operator's requirements and ensure a stable network supply.

4. Protective functions: A good inverter should have various protective functions to protect the system from overloads, short circuits and other damage.

5. Efficiency: The efficiency of the inverter indicates how efficiently it converts the direct current from the solar modules into alternating current. High efficiency is important, to increase the profitability of the system.

6. Warranty: The inverter should have a long warranty period to protect you from high repair costs.

7. Price: The price of an inverter can vary depending on the performance, technology and features. It is important to one to find good value for money.

8. Manufacturer: Choose an inverter from a reputable manufacturer that is known for the quality of its products.

Recommendation:

Choosing the right inverter is complex and should therefore be carried out by a specialist. They can help you choose the one the right device based on your individual requirements and circumstances.

In summary, there are various factors to consider when choosing the right inverter. The performance, the technology, the feed management, the protection functions, the efficiency, the guarantee, the price and the manufacturer play an important role. Therefore, seek advice from a specialist when making your selection.

There are several reasons why the inverter of a photovoltaic system (PV system) may be slightly smaller than the nominal output of the modules should:

Efficiency:

• Inverters work in the optimal efficiency range, when they are operated between 75% and 120% of their nominal output. An inverter that is too small can lead to shutdowns, span> when the modules reach the nominal power. An inverter that is too large, on the other hand, constantly works in the inefficient range.
• Most PV systems never reach their peak performance at the same time, because different modules are influenced by different orientations, shading or weather influences. A smaller inverter can make better use of the system's performance, because it does not always have to be designed for maximum performance.

Costs:

• A smaller inverter is usually cheaper to purchase.
• Installing and maintaining a smaller inverter is easier and cheaper.

Lifespan:

• Inverters, that are operated in the optimal efficiency range, have a longer service life.

Flexibility:

• A smaller inverter can later be more easily replaced by a larger model, if electricity demand increases or the PV system is expanded.

Please note:

• It is important, that the inverter is the right size for the specific requirements of the PV system. To do this, factors such as the module performance, the orientation and shading of the system as well as the expected power consumption are taken into account.
• When choosing an inverter, the functions and quality of the device should also be taken into account.

Rule of thumb:

• The rule of thumb is that the inverter should have around 80% to 90% of the nominal output of the PV system.
• With modern inverters with intelligent shadow management, oversizing can even be up to 120%.

Conclusion:

Choosing the right inverter is an important factor for the efficiency and profitability of a PV system. A slightly smaller inverter can be the right choice in many cases, as it offers advantages in terms of efficiency, costs, service life and flexibility.

Disadvantages of an inverter that is too large:

Inefficiency:

• The inverter usually works in the inefficient range, because the PV system rarely reaches its nominal output. This leads to higher losses and lower efficiency. span>
• Especially in small PV systems, the inverter's own consumption can make up a significant proportion of the energy generated.

Higher costs:

• An inverter that is too large is usually more expensive to purchase.
• The installation and maintenance of a larger inverter is also more complex and expensive.

Unnecessary space required:

• A larger inverter requires more space and can therefore make installation more difficult.

No performance increase:

• An inverter that is too large does not lead to a higher power generation from the PV system. The system can generate a maximum of the power which is supplied by the modules.

Possible problems:

• Inverter overload:
  • In the worst case scenario, the inverter can be overloaded, if the PV system significantly exceeds the rated output of the inverter. This can result in the system being switched off System or even damage to the inverter.
• Heat development:
  • Inverters generate heat when operating. An inverter that is too large can heat up more, which can impair cooling and shorten the service life. li>

Conclusion:

Choosing the right inverter is crucial for the efficiency and profitability of a PV system. An inverter that is too large can lead to... higher costs, lead to inefficiency and unnecessary problems.

It is therefore important to carefully adapt the size of the inverter to the performance of the PV system.

Recommendation:

• As a rule, the inverter should be slightly smaller than the nominal output of the PV system.
• Modern inverters with intelligent shadow management can also be larger dimensioned.
• It is advisable to consult a professional when choosing the right inverter.

Basically, operating a photovoltaic system (PV system) without an inverter is not possible because the direct voltage (DC) generated by the solar modules cannot be used for most household appliances or fed into the power grid .

Inverters have the task of:

• To convert the direct current (DC) from the solar modules into standard household alternating current (AC).
• Increase the voltage to the mains voltage.
• To make the electricity grid compliant, so that it can be fed into the public power grid.

However, there are two special cases in which a PV system can be operated without an inverter:

1. Island systems:

• Isolated systems are off-grid PV systems, that store and consume the electricity they generate themselves.
• In this case, a DC system with special DC devices can be used, to use the electricity for your own consumption. span>
• However, most island systems also have a small inverter, to supply devices, that require alternating current.. span>

2. Mobile small systems:

• Small mobile systems, such asB. on mobile homes or boats, can be used with special solar modules are operated, which directly supply direct current.
• This direct current can then be used directly to charge batteries or to operate direct current devices.
• However, the output of these systems is usually low and is not sufficient for the entire electricity needs of a household.

Please note:

• Operating a PV system without an inverter is complex and requires special specialist knowledge.
• Selection of the correct components and installation must be carried out by a qualified electrician.
• The efficiency of direct current systems is usually lower than that of alternating current systems.
• There are some safety risks, that must be taken into account when installing and operating DC systems.

Conclusion:

In most cases, operating a PV system with an inverter is the simplest, most efficient and safest solution.

Operation without an inverter is only possible in special cases and should only be carried out by specialists.